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. According to the surface acoustic wave resonator, the piezoelectric layer at the tail end area of the electrode finger strip in the interdigital electrode is etched to form the groove, the groove is filled with the low-sound-velocity material to form the low-sound-velocity layer, and the area where the low-sound-velocity layer is located is the low-sound-velocity area of the surface acoustic wave resonator, so that transverse mode stray in a band of the surface acoustic wave resonator is inhibited, and the performance of the surface acoustic wave resonator is improved.

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, a filter and an electronic device, which suppresses the lateral mode stray in the surface acoustic wave resonator band and improves the performance of the surface acoustic wave resonator by etching the piezoelectric layer in the end area of ​​the electrode finger in the interdigitated electrode and filling it with a low sound velocity material to form a low sound velocity area. 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] substrate;

[0008] a piezoelectric layer located on one side of the substrate;

[0009] An interdigitated electrode located on a side of the piezoelectric layer away from the substrate; the interdigitated electrode comprises a first bus bar and a second bus bar arranged opposite to each other in a first direction, and 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, both extending along a second 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;

[0010] A first groove and a second groove are located on a surface of the piezoelectric layer facing away from the substrate, wherein the length extension direction of the first groove is the same as the length extension direction of the second groove and is parallel to the second direction; the first groove is located at an end region of the first electrode finger, and the second groove is located at an end region of the second electrode finger;

[0011] A low acoustic velocity layer is located in the first groove and the second groove.

[0012] Preferably, in the above surface acoustic wave resonator, a side surface of the end of the first electrode finger facing the second bus bar and a side surface of the first groove facing the second bus bar are located in the same plane;

[0013] A surface of a side of an end of the second electrode finger facing the first bus bar and a surface of a side of the second groove facing the first bus bar are located in the same plane.

[0014] Preferably, in the above surface acoustic wave resonator, a side surface of the end of the first electrode finger facing the second bus bar and a side surface of the first groove facing the first bus bar are located in the same plane;

[0015] A surface of a side of an end of the second electrode finger facing the first bus bar and a surface of a side of the second groove facing the second bus bar are located in the same plane.

[0016] Preferably, in the above surface acoustic wave resonator, the orthographic projection of the end of the first electrode finger facing the second bus bar is located within the orthographic projection of the first groove;

[0017] An orthographic projection of a side of an end of the second electrode finger facing the first bus bar is located within an orthographic projection of the second groove.

[0018] Preferably, in the above surface acoustic wave resonator, a side surface of the end of the first electrode finger facing the second bus bar and a side surface of the first groove facing the second bus bar are located in the same plane;

[0019] A surface of a side of an end of the second electrode finger facing the first bus bar and a surface of a side of the second groove facing the second bus bar are located in the same plane.

[0020] Preferably, in the above-mentioned surface acoustic wave resonator, the widths of the first groove and the second groove in the first direction vary linearly, nonlinearly or in steps along the second direction.

[0021] Preferably, in the above surface acoustic wave resonator, the widths of the first groove and the second groove in the first direction first increase and then decrease in a direction from one end to the other end of the interdigital electrode;

[0022] Alternatively, the widths of the first groove and the second groove in the first direction first decrease and then increase from one end to the other end of the interdigital electrode.

[0023] Preferably, in the above surface acoustic wave resonator, when the widths of the first groove and the second groove in the first direction vary nonlinearly along the second direction,

[0024] The orthographic projection shapes of the first groove and the second groove on the substrate are semi-elliptical.

[0025] Preferably, in the above surface acoustic wave resonator, when the widths of the first groove and the second groove in the first direction vary nonlinearly along the second direction,

[0026] A boundary projection line of the first groove facing the first bus bar is in the shape of a cosine curve, and a boundary projection line of the second groove facing the second bus bar is in the shape of a cosine curve.

[0027] Preferably, in the above-mentioned surface acoustic wave resonator, an orthographic projection pattern of the first groove on the substrate is different from an orthographic projection pattern of the second groove on the substrate.

[0028] Preferably, in the above-mentioned surface acoustic wave resonator, the surface acoustic wave resonator further comprises:

[0029] A reflection grid is located at at least one end of the interdigitated electrodes along the second direction.

[0030] Preferably, in the above surface acoustic wave resonator, the first groove and the second groove also extend to the area where the reflection grating is located.

[0031] Preferably, in the above surface acoustic wave resonator, a piston structure is provided at the end of the first electrode finger and / or the end of the second electrode finger;

[0032] The thickness of the electrode finger provided with the piston structure is smaller than the thickness of the piston structure.

[0033] Preferably, in the above-mentioned surface acoustic wave resonator, the material of the low acoustic velocity layer is at least one of a silicon dioxide material, a polyimide material or a tantalum pentoxide material.

[0034] 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.

[0035] 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;

[0036] Alternatively, the electronic device includes the filter described above.

[0037] By means of the above technical solution, the present application provides a surface acoustic wave resonator, a filter and an electronic device. A groove is formed by etching the piezoelectric layer in the end area of ​​the electrode finger strip in the interdigitated electrode, and a low acoustic velocity material is filled in the groove to form a low acoustic velocity layer. The area where the low acoustic velocity layer is located is the low acoustic velocity area of ​​the surface acoustic wave resonator, thereby suppressing the lateral mode stray in the surface acoustic wave resonator band and improving the performance of the surface acoustic wave resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] 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.

[0039] Figure 1 A schematic diagram of a top view of a surface acoustic wave resonator provided by an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0041] Figure 3 For along Figure 1 Schematic diagram of the cross section in the AA' direction and the corresponding schematic diagram of the sound velocity distribution;

[0042] Figure 4 For along Figure 2 Schematic diagram of the cross section in the BB' direction and the corresponding schematic diagram of the sound velocity distribution;

[0043] Figure 5 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0044] Figure 6 For along Figure 5 Schematic diagram of the cross section in the CC' direction and the corresponding schematic diagram of the sound velocity distribution;

[0045] Figure 7 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0046] Figure 8 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0047] Fig. 9 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0048] Fig.10 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0049] Fig.11 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0050] Fig.12 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0051] Fig.13 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0052] Fig.14 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0053] Fig.15 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0054] Fig.16 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;

[0055] Fig.17 A schematic diagram of the top structure of a TC-SAW filter provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] For any type of SAW resonator, due to the acoustic waves propagating laterally in the surface acoustic wave resonator, the surface acoustic wave resonator has a lateral resonant mode, or the electrode fingers excite other resonant modes other than the main acoustic mode, which is reflected in the clutter in and near the passband of the surface acoustic wave resonator. This clutter will increase the loss of the surface acoustic wave resonator, cause the Q value to fluctuate greatly, and reduce the performance of the resonator and the filter. In the prior art, the design of inclined interdigitated electrodes is usually used to suppress in-band spurious (or called lateral mode), but the Q value of the surface acoustic wave resonator will decrease as the inclination angle of the interdigitated electrodes increases, resulting in a contradiction between in-band spurious and Q value. In particular, there is usually a strong lateral mode in the passband of the TC-SAW device, and there is electrical and acoustic coupling between the resonator and the capacitor integrated on the same substrate, resulting in an increase in the insertion loss of the filter passband and a deterioration in the suppression performance of the stopband.

[0063] Based on this, the embodiments of the present invention provide a surface acoustic wave resonator, a filter and an electronic device. By etching the piezoelectric layer at the end region of the electrode finger in the interdigitated electrode and filling it with low sound velocity materials such as SiO2 to form a low sound velocity region, the lateral mode stray in the surface acoustic wave resonator band is suppressed, and the performance of the surface acoustic wave resonator is improved.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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 A schematic diagram of a top view of another surface acoustic wave resonator provided in an embodiment of the present invention, referring to Figure 3 , Figure 3 For along Figure 1 Schematic diagram of the cross section in the AA' direction and the corresponding sound velocity distribution diagram, refer to Figure 4 , Figure 4 For along Figure 2 A schematic cross-sectional view along the BB' direction and a schematic view of the corresponding sound velocity distribution. A surface acoustic wave resonator provided by an embodiment of the present invention includes: a substrate 10.

[0068] The piezoelectric layer 11 is located on one side of the substrate 10 .

[0069] An interdigitated electrode 12 is located on a side of the piezoelectric layer 11 away from the substrate 10; wherein the interdigitated electrode 12 includes a bus bar, 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 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 123 and the second bus bar 124 have the same length extension direction, both extending along the second direction, the first direction X and the second direction Y are parallel to the plane where the substrate 10 is located, and the first direction X and the second direction Y intersect; Figure 1 The description is made by taking the first direction X and the second direction Y being perpendicular to each other as an example.

[0070] The length extension directions of the first electrode fingers 123 and the second electrode fingers 124 are the same and are respectively 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, and the multiple second electrode fingers 124 on the second bus bar 122 are arranged at intervals in the second direction Y. 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 are intervals between the multiple first electrode fingers 123 on the first bus bar 121 and the second bus bar 122, and there are intervals 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 to form so-called interdigitated electrodes. 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. Conversely, when the first bus bar 121 and the first electrode fingers 123 thereon are used as the receiving end, the second bus bar 122 and the second electrode fingers 124 thereon are used as the transmitting end. The transmitting end part is used to convert the electrical signal into an acoustic wave, and the acoustic wave mainly propagates on the surface of the substrate, and the receiving end part is used to convert the received acoustic wave into an electrical signal output, thereby realizing filtering.

[0071] The first groove 13 and the second groove 14 are located on the surface of the piezoelectric layer 11 on the side facing away from the substrate 10 , and the length extension direction of the first groove 13 is the same as the length extension direction of the second groove 14 , and is parallel to the second direction Y. The first groove 13 is located at the end region of the first electrode finger 123 , and the second groove 14 is located at the end region of the second electrode finger 124 .

[0072] The low sound velocity layer is located in the first groove 13 and the second groove 14 .

[0073] Specifically, in the embodiment of the present invention, the end region of the first electrode finger 123 is a region of one end of the first electrode finger 123 away from the first bus bar 121, and the end region of the second electrode finger 124 is a region of one end of the second electrode finger 124 away from the second bus bar 122. The surface acoustic wave resonator provided in the embodiment of the present invention forms a low acoustic velocity layer by etching the piezoelectric layer 11 in the end region of the electrode finger in the interdigitated electrode and filling it with a low acoustic velocity material such as SiO2. Figure 3 and Figure 4 As shown, the area where the low acoustic velocity layer is located is the low acoustic velocity area of ​​the surface acoustic wave resonator, thereby suppressing the transverse mode stray in the surface acoustic wave resonator band and improving the performance of the surface acoustic wave resonator.

[0074] The material of the low acoustic velocity layer includes but is not limited to at least one of silicon dioxide material, polyimide material or tantalum pentoxide material.

[0075] In an optional embodiment of the present invention, Figure 1 As shown, the orthographic projection of the first groove 13 on the substrate 10 overlaps with the orthographic projection of the end of the first electrode finger 123 on the substrate 10, and overlaps with the orthographic projection of the second electrode finger 124 on the substrate 10. The distance between the side surface of the end of the first electrode finger 123 facing the second bus bar 122 and the second bus bar 122 is L1, and the distance between the side surface of the first groove 13 facing the second bus bar 122 and the second bus bar 122 is L2, L1=L2. It can be understood that the side surface of the end of the first electrode finger 123 facing the second bus bar 122 and the side surface of the first groove 13 facing the second bus bar 122 are located in the same plane.

[0076] The orthographic projection of the second groove 14 on the substrate 10 overlaps with the orthographic projection of the end of the second electrode finger 124 on the substrate 10, and overlaps with the orthographic projection of the first electrode finger 123 on the substrate 10. The distance between the side surface of the end of the second electrode finger 124 facing the first bus bar 121 and the first bus bar 121 is L3, and the distance between the side surface of the second groove 14 facing the first bus bar 121 and the first bus bar 121 is L4, L3=L4. It can be understood that the side surface of the end of the second electrode finger 124 facing the first bus bar 121 and the side surface of the second groove 14 facing the first bus bar 121 are located in the same plane.

[0077] Specifically, in the embodiment of the present invention, the first groove 13 and the second groove 14 are formed by etching the piezoelectric layer 11 directly below the end of the electrode finger strip in the forked electrode, and low acoustic velocity materials such as SiO2 are filled in the grooves to form low acoustic velocity layers. The area where the low acoustic velocity layer is located is the low acoustic velocity zone of the surface acoustic wave resonator, thereby suppressing the lateral mode stray within the surface acoustic wave resonator band and improving the performance of the surface acoustic wave resonator.

[0078] In other words, if Figure 1 In the surface acoustic wave resonator shown, the first groove 13 covers both the end of the first electrode finger 123 and the second electrode finger 124 , and the second groove 14 covers both the end of the second electrode finger 124 and the first electrode finger 123 .

[0079] In an optional embodiment of the present invention, Figure 2 As shown, the orthographic projection of the first groove 13 on the substrate 10 is adjacent to the orthographic projection of the end of the first electrode finger 123 on the substrate 10, and there is an overlapping area with the orthographic projection of the second electrode finger 124 on the substrate 10. The distance between the side surface of the end of the first electrode finger 123 facing the second bus bar 122 and the second bus bar 122 is L5, and the distance between the side surface of the first groove 13 facing the first bus bar 121 and the second bus bar 122 is L6, L5=L6. It can be understood that the side surface of the end of the first electrode finger 123 facing the second bus bar 122 and the side surface of the first groove 13 facing the first bus bar 121 are located in the same plane.

[0080] The orthographic projection of the second groove 14 on the substrate 10 is adjacent to the orthographic projection of the end of the second electrode finger 124 on the substrate 10, and there is an overlapping area with the orthographic projection of the first electrode finger 123 on the substrate 10. The distance between the side surface of the end of the second electrode finger 124 facing the first bus bar 121 and the first bus bar 121 is L7, and the distance between the side surface of the second groove 14 facing the second bus bar 122 and the first bus bar 121 is L8, L7=L8. It can be understood that the side surface of the end of the second electrode finger 124 facing the first bus bar 121 and the side surface of the second groove 14 facing the second bus bar 122 are located in the same plane.

[0081] Specifically, in the embodiment of the present invention, the first groove 13 and the second groove 14 are formed by etching the piezoelectric layer 11 between the end of the electrode finger in the forked electrode and the bus bar, and low acoustic velocity materials such as SiO2 are filled in the grooves to form low acoustic velocity layers respectively. The area where the low acoustic velocity layer is located is the low acoustic velocity zone of the surface acoustic wave resonator, thereby suppressing the lateral mode stray within the surface acoustic wave resonator band and improving the performance of the surface acoustic wave resonator.

[0082] In other words, if Figure 2 In the surface acoustic wave resonator shown, the first groove 13 is located in the interval area between the first electrode finger 123 and the second bus bar 122, and the second groove 14 is located in the interval area between the second electrode finger 124 and the first bus bar 121. At this time, the first groove 13 only covers the second electrode finger 124 and is adjacent to the end of the first electrode finger 123; the second groove 14 only covers the first electrode finger 123 and is adjacent to the end of the second electrode finger 124.

[0083] In an optional embodiment of the present invention, reference Figure 5 , Figure 5 A schematic diagram of a top view of another surface acoustic wave resonator provided in an embodiment of the present invention, referring to Figure 6 , Figure 6 For along Figure 5 A schematic cross-sectional view in the CC' direction and a schematic view of the corresponding sound velocity distribution. The orthographic projection of the first groove 13 on the substrate 10 overlaps with the orthographic projection of the end of the first electrode finger 123 on the substrate 10, and overlaps with the orthographic projection of the second electrode finger 124 on the substrate 10. The distance between the side surface of the end of the first electrode finger 123 facing the second bus bar 122 and the second bus bar 122 is L9, the distance between the side surface of the first groove 13 facing the first bus bar 121 and the second bus bar 122 is L10, and the distance between the side surface of the first groove 13 facing the second bus bar 124 and the second bus bar 124 is L11, L10>L9>L11. It can be understood that the orthographic projection of the end of the first electrode finger 123 facing the second bus bar 122 is located within the orthographic projection of the first groove 13.

[0084] The orthographic projection of the second groove 14 on the substrate 10 overlaps with the orthographic projection of the end of the second electrode finger 124 on the substrate 10, and overlaps with the orthographic projection of the first electrode finger 123 on the substrate 10. The distance between the side surface of the end of the second electrode finger 124 facing the first bus bar 121 and the first bus bar 121 is L12, the distance between the side surface of the second groove 14 facing the second bus bar 122 and the first bus bar 121 is L13, and the distance between the side surface of the second groove 14 facing the first bus bar 121 and the first bus bar 121 is L14, L13>L12>L14. It can be understood that the orthographic projection of the end of the second electrode finger 124 facing the first bus bar 121 is located within the orthographic projection of the second groove 14.

[0085] Specifically, in the embodiment of the present invention, the first groove 13 and the second groove 14 are formed by partially etching the piezoelectric layer 11 directly below the end of the electrode finger in the forked electrode, and partially etching the piezoelectric layer between the end of the electrode finger in the forked electrode and the bus bar, and filling the grooves with low acoustic velocity materials such as SiO2 to form low acoustic velocity layers respectively. The area where the low acoustic velocity layer is located is the low acoustic velocity zone of the surface acoustic wave resonator, thereby suppressing the lateral mode stray within the surface acoustic wave resonator band and improving the performance of the surface acoustic wave resonator.

[0086] In other words, if Figure 5 In the surface acoustic wave resonator shown, the first groove 13 will simultaneously cover the end of the first electrode finger 123 and the second electrode finger 124, and will also extend to cover a portion of the spacing area between the first electrode finger 123 and the second bus bar 122; the second groove 14 will simultaneously cover the end of the second electrode finger 124 and the first electrode finger 123, and will also extend to cover a portion of the spacing area between the second electrode finger 124 and the first bus bar 121.

[0087] In an optional embodiment of the present invention, reference Figure 7 , Figure 7A schematic diagram of a top view structure of another surface acoustic wave resonator provided in an embodiment of the present invention. The orthographic projection of the first groove 13 on the substrate 10 overlaps with the orthographic projection of the end of the first electrode finger 123 on the substrate 10, and overlaps with the orthographic projection of the second electrode finger 124 on the substrate 10. Among them, the distance between the side surface of the end of the first electrode finger 123 facing the second bus bar 122 and the second bus bar 122 is L15, and the distance between the side surface of the first groove 13 facing the second bus bar 122 and the second bus bar 122 is L16, and L15=L16. It can be understood that the side surface of the end of the first electrode finger 123 facing the second bus bar 122 and the side surface of the first groove 13 facing the second bus bar 122 are located in the same plane.

[0088] The orthographic projection of the second groove 14 on the substrate 10 is adjacent to the orthographic projection of the end of the second electrode finger 124 on the substrate 10, and there is an overlapping area with the orthographic projection of the first electrode finger 123 on the substrate 10. The distance between the side surface of the end of the second electrode finger 124 facing the first bus bar 121 and the first bus bar 121 is L17, and the distance between the side surface of the second groove 14 facing the second bus bar 122 and the first bus bar 121 is L18, and L17=L18. It can be understood that the side surface of the end of the second electrode finger 124 facing the first bus bar 121 and the side surface of the second groove 14 facing the second bus bar 122 are located in the same plane.

[0089] Specifically, in the embodiment of the present invention, the first groove 13 is formed by etching the piezoelectric layer 11 directly below the end of the first electrode finger 123 in the forked electrode, and the second groove 14 is formed by etching the piezoelectric layer 11 between the end of the second electrode finger 124 in the forked electrode and the first bus bar 121, and low acoustic velocity materials such as SiO2 are filled in the grooves to form low acoustic velocity layers. The area where the low acoustic velocity layer is located is the low acoustic velocity zone of the surface acoustic wave resonator, thereby suppressing the lateral mode stray within the surface acoustic wave resonator band and improving the performance of the surface acoustic wave resonator.

[0090] In other words, if Figure 7 In the surface acoustic wave resonator shown, the first groove 13 covers both the end of the first electrode finger 123 and the second electrode finger 124 ; the second groove 14 is located in the spacing area between the second electrode finger 124 and the first bus bar 121 , and the second groove 14 only covers the first electrode finger 123 and is adjacent to the end of the second electrode finger 124 .

[0091] It should be noted that the relative position relationship between the groove and the electrode finger strip may also have other variations and is not limited to the Figure 1-Figure 7 The relative positional relationships shown are not listed one by one here.

[0092] 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 by an embodiment of the present invention, Fig. 9 A schematic diagram of a top view of another surface acoustic wave resonator provided in an embodiment of the present invention, referring to 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, referring to Fig.11 , Fig.11 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention: The widths of the first groove 13 and the second groove 14 in the first direction X vary linearly, nonlinearly or in steps along the second direction Y.

[0093] Specifically, in the embodiments of the present invention, Figure 8 As shown, the boundary projection line of the first groove 13 facing the first bus bar 121 is a zigzag line, and the boundary projection line of the first groove 13 facing the second bus bar 122 is a straight line; the boundary projection line of the second groove 14 facing the second bus bar 122 is a zigzag line, and the boundary projection line of the second groove 14 facing the first bus bar 121 is a straight line. At this time, the width of the first groove 13 and the second groove 14 in the first direction X increases first and then decreases from one end to the other end of the interdigital electrode, showing a linear change.

[0094] refer to Fig. 9 , Fig. 9 A 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 first groove 13 facing the first bus bar 121 is a zigzag line, and the boundary projection line of the first groove 13 facing the second bus bar 122 is a straight line; the boundary projection line of the second groove 14 facing the second bus bar 122 is a zigzag line, and the boundary projection line of the second groove 14 facing the first bus bar 121 is a straight line. At this time, the width of the first groove 13 and the second groove 14 in the first direction X first decreases and then increases from one end to the other end of the interdigitated electrode, showing a linear change.

[0095] like Fig.10As shown, the boundary projection line of the first groove 13 facing the first bus bar 121 is curved, and the boundary projection line of the first groove 13 facing the second bus bar 122 is straight; the boundary projection line of the second groove 14 facing the second bus bar 122 is curved, and the boundary projection line of the second groove 14 facing the first bus bar 121 is straight. At this time, the width of the first groove 13 and the second groove 14 in the first direction X increases first and then decreases from one end to the other end of the interdigital electrode, showing a nonlinear change.

[0096] like Fig.11 As shown, the boundary projection line of the first groove 13 facing the first bus bar 121 is in a step shape, and the boundary projection line of the first groove 13 facing the second bus bar 122 is in a straight line shape; the boundary projection line of the second groove 14 facing the second bus bar 122 is in a step shape, and the boundary projection line of the second groove 14 facing the first bus bar 121 is in a straight line shape. At this time, the width of the first groove 13 and the second groove 14 in the first direction X increases first and then decreases from one end to the other end of the interdigital electrode, showing a step change.

[0097] By controlling the width of the first groove 13 and the second groove 14 in the first direction X to vary linearly, nonlinearly or in steps along the second direction Y, more sound 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.

[0098] refer to Fig.12 , Fig.12 A 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 first groove 13 facing the first bus bar 121 is a broken line, and the boundary projection line of the first groove 13 facing the second bus bar 122 is a straight line; the boundary projection line of the second groove 14 facing the second bus bar 122 is a broken line, and the boundary projection line of the second groove 14 facing the first bus bar 121 is a straight line. At this time, the width of the first groove 13 and the second groove 14 in the first direction X first increases and then decreases from one end to the other end of the interdigitated electrode, showing a linear change. But compared Figure 8 and Fig. 9 For the structure shown, Figure 8 and Fig. 9 The widths of the first groove 13 and the second groove 14 shown in the first direction X vary uniformly and symmetrically along the second direction Y; Fig.12The widths of the first groove 13 and the second groove 14 shown in the first direction X vary unevenly and asymmetrically along the second direction Y.

[0099] In general, the width of the first groove 13 and the second groove 14 in the first direction X may vary uniformly or unevenly along the second direction Y, may be symmetrical or asymmetrical, may vary linearly or nonlinearly, may vary in steps, and other variations. The specific selection may be determined according to actual conditions and is not limited in the embodiments of the present invention. In some optional embodiments, the orthographic projection of the first groove 13 and the second groove 14 on the substrate may also be a trapezoid, a circle, an ellipse, etc., or half of these shapes. Preferably, the orthographic projection of the first groove 13 and the second groove 14 on the substrate may be a semi-ellipse.

[0100] based on Fig.10 For the structure shown, the boundary projection line of the first groove 13 facing the first bus bar 121 is preferably a cosine curve, and the boundary projection line of the second groove 14 facing the second bus bar 122 is a cosine curve.

[0101] Optionally, a boundary projection line of the first groove 13 facing the first bus bar 121 may also be in the shape of a sine curve, and a boundary projection line of the second groove 14 facing the second bus bar 122 may also be in the shape of a sine curve.

[0102] In an optional embodiment of the present invention, reference Fig.13 , Fig.13 A schematic diagram of a top view of another surface acoustic wave resonator provided by an embodiment of the present invention: The orthographic projection pattern of the first groove 13 on the substrate is different from the orthographic projection pattern of the second groove 14 on the substrate.

[0103] Specifically, in the embodiments of the present invention, Fig.13 As shown, the boundary projection line of the first groove 13 facing the first bus bar 121 is a broken line, and the boundary projection line of the first groove 13 facing the second bus bar 122 is a straight line. At this time, the width of the first groove 13 in the first direction X first increases and then decreases from one end to the other end of the interdigital electrode, showing a linear change. The boundary projection line of the second groove 14 facing the second bus bar 122 is a curved line, and the boundary projection line of the second groove 14 facing the first bus bar 121 is a straight line. At this time, the width of the second groove 14 in the first direction X first increases and then decreases from one end to the other end of the interdigital electrode, showing a nonlinear change.

[0104] It should be noted that the graphic designs of the first groove 13 and the second groove 14 , as well as the corresponding relationship between the graphics therebetween, may also have other variations, which are not listed here one by one.

[0105] In an optional embodiment of the present invention, reference Fig.14 , Fig.14 A schematic diagram of a top view of another surface acoustic wave resonator provided in an embodiment of the present invention, referring 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 surface acoustic wave resonator provided by an embodiment of the present invention also includes:

[0106] The reflection grating 15 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 15 is provided at both ends of the interdigital electrode 12 along the second direction Y as an example for description.

[0107] Specifically, in an embodiment of the present invention, a reflection grating 15 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.

[0108] When the surface acoustic wave resonator provided by the embodiment of the present invention includes a reflection grating, such as Fig.14 As shown, the first groove 13 and the second groove 14 do not extend to the area where the reflective grating is located; Fig.15 As shown, the first groove 13 and the second groove 14 also extend to the area where the reflective grating 15 is located, which is not limited in the embodiment of the present invention and can be reasonably designed according to actual conditions.

[0109] In an optional embodiment of the present invention, a piston structure is provided at the end of the first electrode finger 123 and / or the end of the second electrode finger 124 .

[0110] Specifically, in the embodiment of the present invention, the piston structure 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 piston structure is formed by thickening the end of the first electrode finger 123 and / or the end of the second electrode finger 124 by stacking two metal layers. The piston structure 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), so as to further enhance the suppression effect of the transverse mode and improve the performance of the surface acoustic wave resonator.

[0111] refer to Fig.16 , Fig.16 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. In the prior art solution structure, the piezoelectric layer is not etched to form the first groove and the second groove, while the technical solution structure of the present application etches the piezoelectric layer at the end of the electrode finger to form the first groove and the second groove, and a low sound velocity layer is provided in the first groove and the second groove.

[0112] in, Fig.16 The lower half of the curve is the frequency response curve corresponding to the structure of the technical solution of this application, and the upper half of the curve is the frequency response curve corresponding to the structure of the prior art solution. Fig.16 As shown, in the structure of the technical solution of the present application, all in-band lateral modes except SH stray are suppressed.

[0113] 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.

[0114] For TC-SAW filters, there is usually a strong lateral mode in the passband, and there is electrical and acoustic coupling between the surface acoustic wave resonator and the capacitor integrated on the same substrate. Therefore, in the embodiment of the present invention, the electrical and acoustic coupling can be weakened by etching the piezoelectric layer between the surface acoustic wave resonators and under the capacitor.

[0115] refer to Fig.17 , Fig.17 A schematic diagram of a top view structure of a TC-SAW filter provided in an embodiment of the present invention. The surface acoustic wave resonator A, the surface acoustic wave resonator B and the capacitor C can be connected in series or in parallel, including three parallel connections, three series connections, one parallel to two series connections or two series to one parallel connection, and the specific connection relationship is not limited in the embodiment of the present invention.

[0116] It should be noted that when the filter includes multiple surface acoustic wave resonators, it is necessary to improve at least one surface acoustic wave resonator according to the technical solution of the present application.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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: substrate; a piezoelectric layer located on one side of the substrate; An interdigitated electrode located on a side of the piezoelectric layer away from the substrate; the interdigitated electrode comprises a first bus bar and a second bus bar arranged opposite to each other in a first direction, and 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, both extending along a second 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 first groove and a second groove are located on a surface of the piezoelectric layer facing away from the substrate, wherein the length extension direction of the first groove is the same as the length extension direction of the second groove and is parallel to the second direction; the first groove is located at an end region of the first electrode finger, and the second groove is located at an end region of the second electrode finger; A low acoustic velocity layer is located in the first groove and the second groove.

2. The surface acoustic wave resonator according to claim 1, characterized in that: A side surface of the end of the first electrode finger facing the second bus bar and a side surface of the first groove facing the second bus bar are located in the same plane; A surface of a side of an end of the second electrode finger facing the first bus bar and a surface of a side of the second groove facing the first bus bar are located in the same plane.

3. The surface acoustic wave resonator according to claim 1, characterized in that: A surface of one side of the end of the first electrode finger facing the second bus bar and a surface of one side of the first groove facing the first bus bar are located in the same plane; A surface of a side of an end of the second electrode finger facing the first bus bar and a surface of a side of the second groove facing the second bus bar are located in the same plane.

4. The surface acoustic wave resonator according to claim 1, characterized in that: The orthographic projection of the end of the first electrode finger facing the second bus bar is located within the orthographic projection of the first groove; An orthographic projection of a side of an end of the second electrode finger facing the first bus bar is located within an orthographic projection of the second groove.

5. The surface acoustic wave resonator according to claim 1, characterized in that: A side surface of the end of the first electrode finger facing the second bus bar and a side surface of the first groove facing the second bus bar are located in the same plane; A surface of a side of an end of the second electrode finger facing the first bus bar and a surface of a side of the second groove facing the second bus bar are located in the same plane.

6. The surface acoustic wave resonator according to any one of claims 1 to 5, characterized in that: The widths of the first groove and the second groove in the first direction vary linearly, nonlinearly or in steps along the second direction.

7. The surface acoustic wave resonator according to claim 6, characterized in that: The widths of the first groove and the second groove in the first direction first increase and then decrease from one end to the other end of the interdigital electrode; Alternatively, the widths of the first groove and the second groove in the first direction first decrease and then increase from one end to the other end of the interdigital electrode.

8. The surface acoustic wave resonator according to claim 6, characterized in that: When the widths of the first groove and the second groove in the first direction vary nonlinearly along the second direction, The orthographic projection shapes of the first groove and the second groove on the substrate are semi-elliptical.

9. The surface acoustic wave resonator according to claim 6, characterized in that: When the widths of the first groove and the second groove in the first direction vary nonlinearly along the second direction, A boundary projection line of the first groove facing the first bus bar is in the shape of a cosine curve, and a boundary projection line of the second groove facing the second bus bar is in the shape of a cosine curve.

10. The surface acoustic wave resonator according to claim 1, characterized in that: An orthographic projection pattern of the first groove on the substrate is different from an orthographic projection pattern of the second groove on the substrate.

11. 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.

12. The surface acoustic wave resonator according to claim 11, characterized in that: The first groove and the second groove also extend to the area where the reflection grating is located.

13. The surface acoustic wave resonator according to claim 1, characterized in that: A piston structure is provided at the end of the first electrode finger and / or the end of the second electrode finger; The thickness of the electrode finger provided with the piston structure is smaller than the thickness of the piston structure.

14. The surface acoustic wave resonator according to claim 1, characterized in that: The material of the low acoustic velocity layer is at least one of silicon dioxide material, polyimide material or tantalum pentoxide material.

15. A filter, characterized in that: The filter comprises the surface acoustic wave resonator according to any one of claims 1 to 14.

16. An electronic device, characterized in that: The electronic device comprises the surface acoustic wave resonator according to any one of claims 1 to 14; Or, the electronic device comprises the filter according to claim 15.

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