Surface acoustic wave resonator, filter and electronic equipment

Abstract

The invention provides a surface acoustic wave resonator, a filter and electronic equipment, and relates to the technical field of semiconductors. A piston structure is formed in the tail end area of an electrode finger strip, larger sound velocity difference is achieved by changing the sound velocity of the tail end area of the electrode finger strip, and therefore a transverse mode is reflected in different directions to avoid energy dissipation caused by resonance. And a high-sound-velocity material covers the middle area of the interdigital electrode to form a high-sound-velocity layer, and a sound barrier between the middle area and the tail end area of the interdigital electrode is constructed, so that the propagation of a transverse mode is inhibited, and the effect of inhibiting in-band transverse stray is achieved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a surface acoustic wave resonator, a filter and an electronic device. Background Art

[0002] SAW (Surface Acoustic Wave) resonator is the abbreviation of surface acoustic wave resonator. It is a special filtering device made by using its piezoelectric effect and the physical characteristics of surface acoustic wave propagation. It is widely used in various fields, such as radio frequency. Among them, surface acoustic wave is an elastic wave with energy concentrated near the surface.

[0003] In the current SAW product design, the acoustic waves propagating laterally in the SAW resonator cause lateral resonance modes to appear in the SAW resonator, or the electrode fingers excite other resonance modes besides the main acoustic mode, which manifests as clutter in and near the SAW resonator passband. This clutter will reduce the performance of the SAW resonator.

[0004] Therefore, how to improve the performance of surface acoustic wave resonators is the top priority in today's resonator design. Summary of the invention

[0005] In view of the above problems, the present application provides a surface acoustic wave resonator, filter and electronic device, which forms a high acoustic velocity layer by covering a high acoustic velocity material above the central area of ​​the interdigitated electrode, and widens the end of the electrode finger strip to construct an acoustic barrier between the central area and the end area of ​​the interdigitated electrode, thereby suppressing the propagation of the lateral mode and achieving the effect of suppressing the lateral stray in the band. The specific scheme is as follows:

[0006] In a first aspect, the present application provides a surface acoustic wave resonator, the surface acoustic wave resonator comprising:

[0007] Piezoelectric substrate;

[0008] An interdigitated electrode located on one side of the piezoelectric substrate; the interdigitated electrode includes a bus bar and an electrode finger, the bus bar includes a first bus bar and a second bus bar arranged opposite to each other in a first direction, and the electrode finger includes a first electrode finger located on the first bus bar and a second electrode finger located on the second bus bar; the first bus bar and the second bus bar have the same length extension direction and both extend along a second direction, the first direction and the second direction are parallel to the plane where the piezoelectric substrate is located, and the first direction and the second direction intersect;

[0009] A piston structure and a matching structure are arranged on the electrode finger, wherein the piston structure is located at an end of the electrode finger away from a bus bar correspondingly connected to the electrode finger; the piston structure on one of the two adjacent electrode fingers in the second direction is arranged opposite to the matching structure on the other electrode finger; wherein the maximum width of the piston structure in the second direction is greater than the width of the electrode finger in the second direction;

[0010] A high acoustic velocity layer is located on a side of the interdigital electrodes away from the piezoelectric substrate; the orthographic projection of the high acoustic velocity layer on the piezoelectric substrate covers the middle area of ​​the interdigital electrodes.

[0011] Preferably, in the above-mentioned surface acoustic wave resonator, in the first direction, the maximum width of the high acoustic velocity layer is less than or equal to a target width; the target width is the distance between the piston structure and the matching structure on the same electrode finger.

[0012] Preferably, in the above-mentioned surface acoustic wave resonator, an orthographic projection of the high acoustic velocity layer on the piezoelectric substrate does not overlap with an orthographic projection of a portion of the electrode fingers on the piezoelectric substrate.

[0013] Preferably, in the above-mentioned surface acoustic wave resonator, the surface acoustic wave resonator further comprises:

[0014] A reflection grid is located at at least one end of the interdigitated electrodes along the second direction.

[0015] Preferably, in the above surface acoustic wave resonator, the high acoustic velocity layer also extends to the area where the reflection grating is located.

[0016] Preferably, in the above-mentioned surface acoustic wave resonator, the orthographic projection pattern of the piston structure on the piezoelectric substrate is polygonal, circular or elliptical.

[0017] Preferably, in the above-mentioned surface acoustic wave resonator, an orthographic projection pattern of a piston structure located on the first electrode finger on the piezoelectric substrate is different from an orthographic projection pattern of a piston structure located on the second electrode finger on the piezoelectric substrate.

[0018] Preferably, in the above-mentioned surface acoustic wave resonator, the width of the high acoustic velocity layer in the first direction changes linearly, nonlinearly or in steps along the second direction.

[0019] Preferably, in the above-mentioned surface acoustic wave resonator, the width of the high acoustic velocity layer in the first direction first increases and then decreases from one end to the other end of the interdigital electrode;

[0020] Alternatively, the width of the high acoustic velocity layer in the first direction first decreases and then increases from one end to the other end of the interdigital electrode.

[0021] Preferably, in the above-mentioned surface acoustic wave resonator, the thickness of the piston structure is greater than the thickness of the electrode finger provided with the piston structure.

[0022] A second aspect of the present application provides a filter, which includes the surface acoustic wave resonator described in any one of the above items.

[0023] A third aspect of the present application provides an electronic device, the electronic device comprising the surface acoustic wave resonator described in any one of the above items;

[0024] Alternatively, the electronic device includes the filter described above.

[0025] By means of the above technical scheme, the present application provides a surface acoustic wave resonator, a filter and an electronic device, which forms a piston structure in the end area of ​​the electrode finger strip and achieves a larger sound speed difference by changing the sound speed in the end area of ​​the electrode finger strip, so that the transverse mode is reflected in different directions to avoid resonance and energy dissipation; and forms a high sound speed layer by covering the middle area of ​​the forked electrode with a high sound speed material, thereby constructing an acoustic potential barrier between the middle area and the end area of ​​the forked electrode, thereby suppressing the propagation of the transverse mode, thereby achieving the effect of suppressing the lateral stray within the band. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0027] Figure 1 A schematic diagram of a top view of a surface acoustic wave resonator provided by an embodiment of the present invention;

[0028] Figure 2 For along Figure 1 Schematic diagram of the cross section in the AA' direction and the corresponding schematic diagram of the sound velocity distribution;

[0029] Figure 3 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0030] Figure 4 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0031] Figure 5 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0032] Figure 6 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0033] Figure 7 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0034] Figure 8 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0035] Fig. 9 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0036] Fig.10 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0037] Fig.11 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0038] Fig.12 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0039] Fig.13 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0040] Fig.14 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0041] Fig.15 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0042] Fig.16 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0043] Fig.17 A schematic diagram comparing frequency response curves of a prior art solution structure and the technical solution structure of the present application provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] 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 mode 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.

[0045] Surface acoustic wave resonators and filters are acoustic devices widely used in the field of radio frequency. They combine low insertion loss and good suppression performance, and are relatively small in size. They are used to filter out interference from different frequency signals, attenuate some frequency components, and only allow specified frequency components. They are the technical basis for the application of wireless spectrum as a non-renewable scarce resource. The specific principle can be simply understood as based on the piezoelectric properties of piezoelectric materials, using input and output transducers such as interdigital transducers to convert electrical signals into mechanical energy, and then convert them into electrical signals after processing, so as to amplify the required signals, filter out noise signals and improve signal quality. They are widely used in various wireless communication equipment.

[0046] At present, filters are mainly divided into SAW (Surface Acoustic Wave) filters and BAW (Bulk Acoustic Wave) filters. Surface acoustic wave is an elastic wave that is generated and propagated on the surface of a piezoelectric substrate with piezoelectric properties, and the amplitude decreases rapidly as the depth of the piezoelectric substrate increases. For SAW filters, their manufacturing cost is much lower than that of BAW filters. They are used in low-frequency bands, have low insertion loss and good suppression, and are temperature sensitive.

[0047] At the same time, it should be noted that SAW filters also have corresponding limitations. One of them is that they are easily affected by temperature changes. When the temperature rises, the stiffness of the substrate material tends to decrease and the sound speed will also decrease. It can also be said that SAW filters have the defect of temperature drift, that is, the frequency will drift with the operating temperature. Therefore, based on the traditional SAW filter, the TC-SAW filter, that is, the temperature compensated SAW filter, is produced accordingly. It mainly utilizes the temperature elastic properties of the temperature compensation layer (such as SiO2 layer) and the piezoelectric layer opposite to realize the compensation of the temperature drift characteristics.

[0048] It should be further explained that SAW filters also have product designs such as TF film SAW filters, and their POI multi-layer substrates often include Si substrates, piezoelectric film layers, temperature compensation layers and other dielectric layers.

[0049] Among them, the design of the filter often uses the resonator as the basic unit, which can form the corresponding topology and amplify the specified frequency component signal.

[0050] Regardless of the type of SAW resonator, the acoustic waves propagating laterally in the SAW resonator cause the SAW resonator to have a lateral resonant mode, or the electrode fingers excite other resonant modes other than the main acoustic mode, which manifests as clutter in and near the passband of the SAW resonator. This clutter will increase the loss of the SAW resonator, causing the Q value to fluctuate greatly, and reduce the performance of the resonator and filter. In the prior art, the design of inclined interdigitated electrodes is usually used to suppress in-band spurious (or lateral mode), but the Q value of the SAW resonator will decrease as the inclination angle of the interdigitated electrodes increases, resulting in a contradiction between in-band spurious and Q value.

[0051] Based on this, the embodiments of the present invention provide a surface acoustic wave resonator, filter and electronic device. By covering the central area of ​​the interdigitated electrode with a high acoustic velocity material to form a high acoustic velocity layer, and widening the ends of the electrode fingers, an acoustic barrier is constructed between the central area and the end area of ​​the interdigitated electrode to suppress the propagation of the lateral mode, thereby achieving the effect of suppressing the lateral stray in the band.

[0052] It should be noted that the technical solution provided in the embodiment of the present invention can be applied to a common SAW resonator, a TC-SAW resonator or a TF-SAW resonator, and the specific type of the resonator is not limited in the embodiment of the present invention.

[0053] 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.

[0054] 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.

[0055] refer to Figure 1 , Figure 1 A schematic diagram of a top view of a surface acoustic wave resonator provided in an embodiment of the present invention, referring to Figure 2 , Figure 2 For along Figure 1 A schematic cross-sectional view of the AA' direction and a corresponding schematic diagram of the sound velocity distribution. A surface acoustic wave resonator provided by an embodiment of the present invention comprises:

[0056] The piezoelectric substrate 11 has piezoelectric properties. It should be noted that when the surface acoustic wave resonator is a TC-SAW resonator or a common SAW resonator, the piezoelectric substrate 11 is made of a piezoelectric material; when the surface acoustic wave resonator is a TF-SAW resonator, the piezoelectric substrate 11 is a substrate with a piezoelectric film layer.

[0057] The interdigitated electrode 12 is located on one side of the piezoelectric substrate 11; wherein the interdigitated electrode 12 includes a bus bar and an electrode finger, the bus bar includes a first bus bar 121 and a second bus bar 122 arranged opposite to each other in a first direction X, and the electrode finger includes a first electrode finger 123 located on the first bus bar 121 and a second electrode finger 124 located on the second bus bar 122. The first bus bar 121 and the second bus bar 122 have the same length extension direction, both extending along the second direction Y, the first direction X and the second direction Y are parallel to the plane where the piezoelectric substrate 11 is located, and the first direction X and the second direction Y intersect, and in the embodiment of the present invention, the first direction X and the second direction Y are perpendicular to each other for illustration.

[0058] The length extension direction of the first electrode fingers 123 and the second electrode fingers 124 is parallel to the first direction X, the multiple first electrode fingers 123 on the first bus bar 121 are arranged at intervals in the second direction Y, the multiple second electrode fingers 124 on the second bus bar 122 are arranged at intervals in the second direction Y, and the multiple first electrode fingers 123 on the first bus bar 121 and the multiple second electrode fingers 124 on the second bus bar 122 are arranged crosswise in sequence in the second direction Y, and there is a gap between the multiple first electrode fingers 123 on the first bus bar 121 and the second bus bar 122, and there is a gap between the multiple second electrode fingers 124 on the second bus bar 122 and the first bus bar 121. At this time, the bus bars and the electrode fingers are distributed in a manner similar to crossing fingers, forming a so-called interdigitated electrode 12. When the first bus bar 121 and the first electrode fingers 123 thereon are used as the transmitting end, the second bus bar 122 and the second electrode fingers 124 thereon are used as the receiving end. On the contrary, when the first bus bar 121 and the first electrode fingers 123 thereon serve as the receiving end, the second bus bar 122 and the second electrode fingers 124 thereon serve as the transmitting end. The transmitting end portion is used to convert the electrical signal into an acoustic wave, and the acoustic wave mainly propagates on the surface of the piezoelectric substrate; the receiving end portion is used to convert the received acoustic wave into an electrical signal output, thereby achieving filtering.

[0059] A piston structure 13 and a matching structure 14 are provided on the electrode finger. The piston structure 13 is located at one end of the electrode finger away from the bus bar correspondingly connected to the electrode finger. It can also be understood that the piston structure 13 is located at the end of the electrode finger, wherein the piston structure 13 on one of the two adjacent electrode fingers in the second direction Y is arranged opposite to the matching structure 14 on the other electrode finger.

[0060] The maximum width of the piston structure 13 in the second direction Y is greater than the width of the electrode fingers in the second direction Y.

[0061] The high acoustic velocity layer 15 is located on the side of the interdigital electrode 12 facing away from the piezoelectric substrate 11 , and the orthographic projection of the high acoustic velocity layer 15 on the piezoelectric substrate 11 covers the middle area of ​​the interdigital electrode 12 .

[0062] Specifically, in the embodiment of the present invention, a piston structure 13 is formed in the end region of the electrode finger strip, and a larger sound velocity difference is achieved by changing the sound velocity in the end region of the electrode finger strip, so that the transverse mode is reflected in different directions to avoid resonance and energy dissipation; and a high sound velocity layer 15 is formed by covering the middle region of the forked electrode 12 with a high sound velocity material, so as to construct an acoustic potential barrier between the middle region and the end region of the forked electrode 12, thereby suppressing the propagation of the transverse mode, thereby achieving the effect of suppressing in-band lateral stray.

[0063] It should be noted that in the embodiments of the present invention, Figure 2 As shown, a temperature compensation layer 17 may be further provided between the interdigital electrodes 12 and the high acoustic velocity layer 15 , and the temperature drift characteristics may be compensated by utilizing the opposite temperature elasticity characteristics of the temperature compensation layer 17 and the piezoelectric substrate 11 .

[0064] In an optional embodiment of the present invention, reference Figure 3 , Figure 3 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention. In the first direction X, the maximum width of the high acoustic velocity layer 15 is less than or equal to the target width, which is the distance between the piston structure 13 and the matching structure 14 on the same electrode finger.

[0065] Specifically, in the embodiments of the present invention, Figure 1 As shown, in the first direction X, the maximum width of the high acoustic velocity layer 15 is smaller than the target width, and the target width is the distance between the piston structure 13 and the matching structure 14 on the same electrode finger. Figure 3 As shown, in the first direction X, the maximum width of the high acoustic velocity layer 15 is equal to the target width, and the target width is the distance between the piston structure 13 and the matching structure 14 on the same electrode finger. In other words, in the embodiment of the present invention, the high acoustic velocity layer 15 can completely cover the middle area of ​​the interdigital electrode 12 in the longitudinal direction, or can partially cover the middle area of ​​the interdigital electrode 12.

[0066] In an optional embodiment of the present invention, reference Figure 4 , Figure 4 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention is shown in FIG. The orthographic projection of the high acoustic velocity layer 15 on the piezoelectric substrate 11 does not overlap with the orthographic projection of part of the electrode fingers on the piezoelectric substrate 11 .

[0067] Specifically, in the embodiments of the present invention, Figure 1 and Figure 3 As shown, the orthographic projection of the high acoustic velocity layer 15 on the piezoelectric substrate 11 completely covers all electrode fingers in the interdigital electrode 12, that is, the orthographic projection of the high acoustic velocity layer 15 on the piezoelectric substrate 11 covers any electrode finger in the interdigital electrode 12. Figure 4 As shown, the orthographic projection of the high acoustic velocity layer 15 on the piezoelectric substrate 11 only covers part of the electrode fingers in the interdigitated electrodes 12, that is, the high acoustic velocity layer 15 is not formed above some of the electrode fingers. In other words, in the embodiment of the present invention, the high acoustic velocity layer 15 can cover any electrode finger in the interdigitated electrodes 12 in the lateral direction, or can only cover part of the electrode fingers in the interdigitated electrodes 12.

[0068] In an optional embodiment of the present invention, reference Figure 5 , Figure 5 A schematic diagram of a top view structure of another surface acoustic wave resonator provided in an embodiment of the present invention. In the first direction X, the maximum width of the high acoustic velocity layer 15 is smaller than the target width, and the orthographic projection of the high acoustic velocity layer 15 on the piezoelectric substrate 11 does not overlap with the orthographic projection of part of the electrode fingers on the piezoelectric substrate 11; the target width is the distance between the piston structure 13 and the matching structure 14 on the same electrode finger.

[0069] Specifically, in the embodiments of the present invention, Figure 5 As shown, the high acoustic velocity layer 15 partially covers the middle region of the interdigital electrode 12 in the longitudinal direction, and covers part of the electrode fingers in the interdigital electrode 12 in the transverse direction.

[0070] It should be noted that in the embodiment of the present invention, there are other combinations of the high acoustic velocity layer 15 in the horizontal and vertical directions. For example, the high acoustic velocity layer 15 covers the electrode fingers in the middle of the forked electrode 12 in the horizontal direction, and the high acoustic velocity layer 15 is not formed above the electrode fingers on the edges of both sides. Or, the high acoustic velocity layer 15 covers the electrode fingers in one area of ​​the forked electrode 12 in the horizontal direction, and the high acoustic velocity layer 15 is not formed above the electrode fingers in the other area. The design of the high acoustic velocity layer 15 can be flexibly set according to actual conditions, which can indirectly reflect the structural diversity of the surface acoustic wave resonator provided in the embodiment of the present invention, and is not strictly limited in the embodiment of the present invention.

[0071] In an optional embodiment of the present invention, reference Figure 6 , Figure 6 A schematic diagram of a top view of another surface acoustic wave resonator provided in an embodiment of the present invention, referring to Figure 7 , Figure 7A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention. The surface acoustic wave resonator provided by an embodiment of the present invention also includes:

[0072] The reflection grating 16 is located at at least one end of the interdigital electrode 12 along the second direction Y. It should be noted that in the embodiment of the present invention, the reflection grating 16 is provided at both ends of the interdigital electrode 12 along the second direction Y as an example for description.

[0073] Specifically, in an embodiment of the present invention, a reflection grating 16 can also be set at at least one end of the interdigitated electrode 12 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 surface acoustic wave resonator.

[0074] When the surface acoustic wave resonator provided by the embodiment of the present invention includes the reflection grating 16, as Figure 6 As shown, the high acoustic velocity layer 15 does not extend to the area where the reflection grid 16 is located; Figure 7 As shown, the high sound velocity layer 15 also extends to the area where the reflection grid 16 is located. When the high sound velocity layer 15 also extends to the area where the reflection grid 16 is located, the high sound velocity layer 15 can partially or completely cover the area where the reflection grid 16 is located, which is not limited in the embodiment of the present invention and can be reasonably designed according to actual conditions.

[0075] In an optional embodiment of the present invention, reference Figure 8 , Figure 8 A schematic diagram of a top view of another surface acoustic wave resonator provided in an embodiment of the present invention, referring to Fig. 9 , Fig. 9 The top view of another surface acoustic wave resonator provided by the embodiment of the present invention is a schematic diagram. In the embodiment of the present invention, the orthographic projection of the piston structure 13 on the piezoelectric substrate 11 is a polygon, a circle or an ellipse. Figure 8 As shown, the orthographic projection of the piston structure 13 and the matching structure 14 on the piezoelectric substrate 11 is a trapezoid in a polygon; Fig. 9 As shown, the orthographic projection patterns of the piston structure 13 and the matching structure 14 on the piezoelectric substrate 11 are ellipses.

[0076] Specifically, in the embodiment of the present invention, the orthographic projection shape of the piston structure on the piezoelectric substrate 11 is not necessarily a rectangle, it can be a variety of orthographic projection shapes including polygons, circles or ellipses, etc. When the piston structure 13 uses a more complex orthographic projection shape, more adjustable parameters can be introduced, and the technical effect of the technical solution of the present invention can be further improved.

[0077] In an optional embodiment of the present invention, reference Fig.10 , Fig.10 A schematic diagram of a top view of another surface acoustic wave resonator provided in an embodiment of the present invention. In an embodiment of the present invention, the orthographic projection pattern of the piston structure 13 located on the first electrode finger 123 on the piezoelectric substrate 11 is different from the orthographic projection pattern of the piston structure 13 located on the second electrode finger 124 on the piezoelectric substrate 11.

[0078] Specifically, in the embodiments of the present invention, Fig.10 As shown, the orthographic projection patterns of the piston structure 13 located on the first electrode finger 123 and the matching structure 14 located on the second electrode finger 124 on the piezoelectric substrate 11 are trapezoidal, and the orthographic projection patterns of the piston structure 13 located on the second electrode finger 124 and the matching structure 14 located on the first electrode finger 123 on the piezoelectric substrate 11 are elliptical. Obviously, the orthographic projection patterns of the piston structure 13 on a part of the first electrode finger 123 on the piezoelectric substrate 11 are different from the orthographic projection patterns of the piston structure 13 on another part of the first electrode finger 123 on the piezoelectric substrate 11.

[0079] That is to say, in the embodiment of the present invention, the design of the piston structure 13 on the electrode finger strip can be diversified. When the design scheme is more complex, more adjustable parameters can be introduced, and the technical effect of the technical scheme of the present invention can be further improved.

[0080] It should be noted that in the embodiment of the present invention, the width and length of the piston structure 13 and the matching structure 14 are not limited, and their specific shapes are not limited either, and they can be conventional rectangles, or trapezoids, circles, or other shapes. In the embodiment of the present invention, the orthographic projection pattern of the piston structure 13 on the piezoelectric substrate 11 is the same as the orthographic projection pattern of the matching structure 14 on the piezoelectric substrate 11 for illustration.

[0081] In an optional embodiment of the present invention, the width of the high acoustic velocity layer 15 in the first direction X varies linearly, nonlinearly or in steps along the second direction Y.

[0082] Specifically, in the embodiments of the present invention, refer to Fig.11 , Fig.11 A schematic diagram of a top view of another surface acoustic wave resonator provided in an embodiment of the present invention, referring to Fig.12 , Fig.12 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention. The boundary projection line of the high acoustic velocity layer 15 facing the first bus bar 121 and the boundary projection line of the high acoustic velocity layer 15 facing the second bus bar 122 are in the shape of a broken line. Fig.11As shown, the width of the high acoustic velocity layer 15 in the first direction X first decreases and then increases from one end to the other end of the interdigital electrode 12, showing a linear change; Fig.12 As shown, the width of the high acoustic velocity layer 15 in the first direction X first increases and then decreases from one end to the other end of the interdigital electrode 12 , showing a linear change.

[0083] refer to Fig.13 , Fig.13 A schematic diagram of a top view of another surface acoustic wave resonator provided in an embodiment of the present invention, referring to Fig.14 , Fig.14 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention. The boundary projection line of the high acoustic velocity layer 15 facing the first bus bar 121 and the boundary projection line of the high acoustic velocity layer 15 facing the second bus bar 122 are curved. Fig.13 As shown, the width of the high acoustic velocity layer 15 in the first direction X first increases and then decreases from one end to the other end of the interdigital electrode 12, showing a nonlinear change; Fig.14 As shown, the width of the high acoustic velocity layer 15 in the first direction X first decreases and then increases from one end to the other end of the interdigital electrode 12 , showing a nonlinear change.

[0084] refer to Fig.15 , Fig.15 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention. The boundary projection line of the high acoustic velocity layer 15 facing the first bus bar 121 and the boundary projection line of the high acoustic velocity layer 15 facing the second bus bar 122 are in a stepped shape. Fig.15 As shown, the width of the high acoustic velocity layer 15 in the first direction X first increases and then decreases from one end to the other end of the interdigital electrode 12 , showing a step-by-step change.

[0085] By controlling the width of the high acoustic velocity layer 15 in the first direction X to vary linearly, nonlinearly or in steps along the second direction Y, more acoustic velocity gradients are obtained at the ends of the electrode fingers, thereby suppressing the lateral mode stray within the surface acoustic wave resonator band to the greatest extent and improving the performance of the surface acoustic wave resonator.

[0086] refer to Fig.16 , Fig.16A schematic diagram of a top view structure of another surface acoustic wave resonator provided in an embodiment of the present invention. The boundary projection line of the high acoustic velocity layer 15 facing the first bus bar 121 and the boundary projection line of the high acoustic velocity layer 15 facing the second bus bar 122 are in the shape of a broken line, and the width of the high acoustic velocity layer 15 in the first direction X increases first and then decreases from one end to the other end of the interdigitated electrode 12, showing a linear change. However, compared Fig.11 and Fig.12 For the structure shown, Fig.11 and Fig.12 The width of the high acoustic velocity layer 15 in the first direction X varies uniformly and symmetrically along the second direction Y; Fig.16 The width of the high acoustic velocity layer 15 in the first direction X varies unevenly and asymmetrically along the second direction Y.

[0087] In general, the width of the high acoustic velocity layer 15 in the first direction X along the second direction Y can be uniform or uneven, symmetrical or asymmetrical, linear or nonlinear, or in steps, and other forms of variation. The specific selection can be determined according to actual conditions and is not limited in the embodiments of the present invention.

[0088] In an optional embodiment of the present invention, the thickness of the piston structure 13 is greater than the thickness of the electrode finger on which the piston structure 13 is disposed.

[0089] Specifically, in the embodiment of the present invention, a thicker piston structure 13 can be formed by thickening the end of the first electrode finger 123 and / or the end of the second electrode finger 124. For example, the end of the first electrode finger 123 and / or the end of the second electrode finger 124 is thickened by stacking two metal layers to form a thicker piston structure 13. The piston structure 13 at the end of the electrode finger can realize optical proximity correction on the one hand; on the other hand, it increases the sound velocity difference of the interface by changing the sound velocity, which helps to form a piston mode (also called Piston mode in the field) to further enhance the suppression effect of the transverse mode and improve the performance of the surface acoustic wave resonator.

[0090] refer to Fig.17 , Fig.17 A schematic diagram comparing the frequency response curves of a prior art solution structure and the technical solution structure of the present application provided in an embodiment of the present invention. The prior art solution structure does not have a high sound velocity layer 15 and a piston structure 13, while the technical solution structure of the present application has a high sound velocity layer 15 and a piston structure 13.

[0091] Among them, curve 1 is the frequency response curve corresponding to the structure of the technical solution of the present application, and curve 2 is the frequency response curve corresponding to the structure of the prior art solution. Fig.17 As shown in a, the curve 1 corresponding to the structure of the technical solution of the present application is smoother; Fig.17 As shown in b, the curve 1 corresponding to the structure of the technical solution of the present application has smaller fluctuations, that is, the difference between the peak and the trough is small, and the sound wave transmission tends to be more stable. In general, the in-band transverse modes are all suppressed in the structure of the technical solution of the present application.

[0092] Based on the above embodiment of the present invention, a filter is provided in another embodiment of the present invention. The filter includes the surface acoustic wave resonator described in the above embodiment.

[0093] Based on the above embodiment of the present invention, another embodiment of the present invention further provides an electronic device, which includes the surface acoustic wave resonator described in the above embodiment. Or, the electronic device includes the filter described in the above embodiment.

[0094] The surface acoustic wave resonator, filter and electronic device provided by the present invention are introduced in detail above. The principle and implementation mode of the present invention are explained in this article by using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

[0095] It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0096] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device that includes a series of elements is inherent to the elements, or also includes elements inherent to these processes, methods, articles or devices. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0097] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 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 surface acoustic wave resonator, characterized in that: The surface acoustic wave resonator comprises: Piezoelectric substrate; An interdigitated electrode located on one side of the piezoelectric substrate; the interdigitated electrode includes a bus bar and an electrode finger, the bus bar includes a first bus bar and a second bus bar arranged opposite to each other in a first direction, and the electrode finger includes a first electrode finger located on the first bus bar and a second electrode finger located on the second bus bar; the first bus bar and the second bus bar have the same length extension direction and both extend along a second direction, the first direction and the second direction are parallel to the plane where the piezoelectric substrate is located, and the first direction and the second direction intersect; A piston structure and a matching structure are arranged on the electrode finger, wherein the piston structure is located at an end of the electrode finger away from a bus bar correspondingly connected to the electrode finger; the piston structure on one of the two adjacent electrode fingers in the second direction is arranged opposite to the matching structure on the other electrode finger; wherein the maximum width of the piston structure in the second direction is greater than the width of the electrode finger in the second direction; A high acoustic velocity layer is located on a side of the interdigital electrodes away from the piezoelectric substrate; the orthographic projection of the high acoustic velocity layer on the piezoelectric substrate covers the middle area of ​​the interdigital electrodes.

2. The surface acoustic wave resonator according to claim 1, characterized in that: In the first direction, the maximum width of the high acoustic velocity layer is less than or equal to a target width; the target width is the distance between the piston structure and the matching structure on the same electrode finger.

3. The surface acoustic wave resonator according to claim 1 or 2, characterized in that: The orthographic projection of the high acoustic velocity layer on the piezoelectric substrate does not overlap with the orthographic projection of part of the electrode fingers on the piezoelectric substrate.

4. The surface acoustic wave resonator according to claim 1, characterized in that: The surface acoustic wave resonator further comprises: A reflection grid is located at at least one end of the interdigitated electrodes along the second direction.

5. The surface acoustic wave resonator according to claim 4, characterized in that: The high sound velocity layer also extends to the area where the reflection grid is located.

6. The surface acoustic wave resonator according to claim 1, characterized in that: The orthographic projection shape of the piston structure on the piezoelectric substrate is polygonal, circular or elliptical.

7. The surface acoustic wave resonator according to claim 1, characterized in that: An orthographic projection pattern of a piston structure located on the first electrode finger on the piezoelectric substrate is different from an orthographic projection pattern of a piston structure located on the second electrode finger on the piezoelectric substrate.

8. The surface acoustic wave resonator according to claim 1, characterized in that: The width of the high acoustic velocity layer in the first direction changes linearly, nonlinearly or in steps along the second direction.

9. The surface acoustic wave resonator according to claim 8, characterized in that: The width of the high acoustic velocity layer in the first direction first increases and then decreases from one end to the other end of the interdigital electrode; Alternatively, the width of the high acoustic velocity layer in the first direction first decreases and then increases from one end to the other end of the interdigital electrode.

10. The surface acoustic wave resonator according to claim 1, characterized in that: The thickness of the piston structure is greater than the thickness of the electrode finger provided with the piston structure.

11. A filter, characterized in that: The filter comprises the surface acoustic wave resonator according to any one of claims 1 to 10.

12. An electronic device, characterized in that: The electronic device comprises the surface acoustic wave resonator according to any one of claims 1 to 10; Or, the electronic device comprises the filter according to claim 11.

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