Surface acoustic wave resonator, filter and electronic equipment

Abstract

The invention discloses a surface acoustic wave resonator, a filter and electronic equipment, and relates to the technical field of radio frequency, compared with an interdigital transducer in an existing surface acoustic wave resonator which is located on the surface, away from a substrate, of a piezoelectric layer, the surface acoustic wave resonator is characterized in that at least part of electrode fingers of the interdigital transducer are embedded into the piezoelectric layer; the depth of the portion, embedded into the piezoelectric layer, of the interdigital transducer is not smaller than 0.02 lambda, and lambda is the wavelength of sound waves transmitted in the surface acoustic wave resonator, so that on one hand, the piezoelectric layer can achieve efficient conversion of electric energy and mechanical energy through the piezoelectric effect, and energy loss is reduced; and on the other hand, the piezoelectric layer and the interdigital transducer are combined more stably, so that stray waves of the surface acoustic wave resonator can be effectively inhibited, in-band stray of the surface acoustic wave resonator is obviously weakened, the Q value of the resonator is further improved, and the performance of the surface acoustic wave resonator is comprehensively improved.

Description

Technical Field

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

[0002] A surface acoustic wave (SAW) resonator is a device widely used in the radio frequency field, which combines low insertion loss and good suppression performance, and has a small volume at the same time. It mainly uses the piezoelectric effect to convert electrical energy and mechanical energy into each other, and is used to combine to achieve the gating characteristic of signal transmission.

[0003] There are various types of surface acoustic wave resonators. For example, a surface acoustic wave resonator with dummy fingers in the interdigital transducer, a surface acoustic wave resonator with reflection gratings arranged on both sides of the interdigital transducer, a temperature-compensation surface acoustic wave (TC-SAW) resonator, and a thin-film surface acoustic wave (Thin-Film SAW, TC-SAW) resonator, etc. For any type of surface acoustic wave resonator, the laterally propagating acoustic wave will cause the resonator to appear a lateral resonance mode, that is, spurious waves in and near the passband. This spurious wave will increase the device loss, cause a large fluctuation in the Q value, and reduce the performance of the resonator and the filter.

[0004] Therefore, how to effectively suppress the spurious waves of the surface acoustic wave resonator, improve the Q value of the resonator, and comprehensively improve the performance of the surface acoustic wave resonator is a technical problem that those skilled in the art need to solve urgently. Summary of the Invention

[0005] To solve the above technical problems, embodiments of the present application provide a surface acoustic wave resonator, a filter, and an electronic device to effectively suppress the spurious waves of the surface acoustic wave resonator, improve the Q value of the resonator, and comprehensively improve the performance of the surface acoustic wave resonator.

[0006] To achieve the above object, embodiments of the present application provide the following technical solutions:

[0007] In a first aspect, embodiments of the present application provide a surface acoustic wave resonator, including:

[0008] A substrate;

[0009] A piezoelectric layer located on one side of the substrate;

[0010] A interdigital transducer that is at least partially embedded in the piezoelectric layer on the side of the piezoelectric layer facing away from the substrate; the interdigital transducer includes a first bus bar and a second bus bar that are oppositely arranged, and electrode fingers connected to the first bus bar and electrode fingers connected to the second bus bar are arranged between the first bus bar and the second bus bar. The electrode fingers connected to the first bus bar and the electrode fingers connected to the second bus bar are alternately arranged along a first direction, the electrode fingers extend along a second direction, the first direction and the second direction are parallel to the plane of the substrate, and the first direction and the second direction are perpendicular; at least part of the electrode fingers of the interdigital transducer are embedded in the piezoelectric layer, and in the direction perpendicular to the plane of the substrate, the depth at which the part of the interdigital transducer embedded in the piezoelectric layer is embedded in the piezoelectric layer is not less than 0.02λ, where λ is the wavelength of the acoustic wave propagating in the surface acoustic wave resonator.

[0011] Optionally, each of the electrode fingers of the interdigital transducer is embedded in the piezoelectric layer.

[0012] Optionally, each of the electrode fingers of the interdigital transducer is embedded in the piezoelectric layer to the same depth.

[0013] Optionally, at least two adjacent electrode fingers of the interdigital transducer along the first direction are embedded in the piezoelectric layer to different depths.

[0014] Optionally, along the first direction, the depth at which each of the electrode fingers of the interdigital transducer is embedded in the piezoelectric layer gradually increases;

[0015] Or, along the first direction, the depth at which each of the electrode fingers of the interdigital transducer is embedded in the piezoelectric layer gradually decreases;

[0016] Or, along the first direction, the depth at which each of the electrode fingers of the interdigital transducer is embedded in the piezoelectric layer first increases and then decreases;

[0017] Or, along the first direction, the depth at which each of the electrode fingers of the interdigital transducer is embedded in the piezoelectric layer first decreases and then increases.

[0018] Optionally, part of the electrode fingers of the interdigital transducer are embedded in the piezoelectric layer, and another part of the electrode fingers of the interdigital transducer are not embedded in the piezoelectric layer, and the electrode fingers of the interdigital transducer embedded in the piezoelectric layer and the electrode fingers not embedded in the piezoelectric layer are alternately arranged.

[0019] Optionally, in the direction perpendicular to the plane of the substrate, the depth at which the part of the interdigital transducer embedded in the piezoelectric layer is embedded in the piezoelectric layer is not greater than 0.06λ.

[0020] Optionally, in a direction perpendicular to the plane of the substrate, a bonding layer is provided between the portion of the interdigital transducer embedded in the piezoelectric layer and the piezoelectric layer.

[0021] Optionally, in a direction perpendicular to the plane of the substrate, the thickness of the bonding layer is not greater than 20 nm.

[0022] Optionally, the material of the bonding layer includes at least one of Ti metal and AlTi alloy.

[0023] Optionally, there is an included angle between the extending direction of at least one of the first bus bar and the second bus bar and the first direction.

[0024] Optionally, the electrode finger includes a first metal layer and a second metal layer stacked in sequence in a direction away from the substrate, and the interface between the first metal layer and the second metal layer in the electrode finger does not coincide with the surface of the piezoelectric layer away from the substrate.

[0025] Optionally, in a plane perpendicular to the second direction, the cross-section of the electrode finger is trapezoidal, and the length of the bottom side of the trapezoid close to the substrate is greater than the length of the bottom side of the trapezoid away from the substrate.

[0026] Optionally, the value range of the two bottom angles corresponding to the bottom side of the trapezoid close to the substrate is 70° - 90°, including the end values.

[0027] Optionally, in a plane perpendicular to the second direction, the cross-section of the electrode finger is rectangular, the two corners of the rectangle away from the substrate are rounded, and the two corners of the rectangle close to the substrate are right angles.

[0028] Optionally, there are also dummy fingers connected to the first bus bar and dummy fingers connected to the second bus bar provided between the first bus bar and the second bus bar. The dummy fingers connected to the first bus bar and the electrode fingers connected to the second bus bar are arranged opposite to each other in the second direction, and the dummy fingers connected to the second bus bar and the electrode fingers connected to the first bus bar are arranged opposite to each other in the second direction;

[0029] Along the extending direction of the dummy finger, the value range of the length of the dummy finger is 0.5λ - 1.5λ, including the end values.

[0030] In a second aspect, an embodiment of the present application provides a filter, including any one of the above surface acoustic wave resonators.

[0031] In a third aspect, an embodiment of the present application provides an electronic device, including the above filter.

[0032] Compared with the prior art, the above technical solution has the following advantages:

[0033] Compared with the interdigital transducer in the existing surface acoustic wave resonator being located on the surface of the piezoelectric layer facing away from the substrate, in the surface acoustic wave resonator provided by the embodiment of the present application, at least part of the electrode fingers of the interdigital transducer are embedded in the piezoelectric layer, and the depth of the part of the interdigital transducer embedded in the piezoelectric layer is not less than 0.02λ, where λ is the wavelength of the acoustic wave propagating in the surface acoustic wave resonator. On the one hand, it is beneficial for the piezoelectric layer to achieve efficient conversion of electrical energy and mechanical energy through the piezoelectric effect, reducing energy loss. On the other hand, it makes the combination of the piezoelectric layer and the interdigital transducer more stable, thereby effectively suppressing the spurious waves of the surface acoustic wave resonator, significantly weakening the in-band spurious of the surface acoustic wave resonator, and further improving the Q value of the resonator, comprehensively improving the performance of the surface acoustic wave resonator.

[0034] Other objects and advantages of the present application will be described in detail in the following embodiments in conjunction with the accompanying drawings. Description of the Drawings

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0036] Figure 1 It is a top view schematic diagram of an existing surface acoustic wave resonator with an inclined interdigital transducer;

[0037] Figure 2 It is a top view schematic diagram of another existing surface acoustic wave resonator with an inclined interdigital transducer;

[0038] Figure 3 It is a top view schematic diagram of yet another existing surface acoustic wave resonator with an inclined interdigital transducer;

[0039] Figure 4 It is a top view schematic diagram of a surface acoustic wave resonator with an inclined interdigital transducer;

[0040] Figure 5 It is Figure 4 The simulation test result diagram of the shown surface acoustic wave resonator;

[0041] Figure 6 It is a top view schematic diagram of an existing surface acoustic wave resonator with a raised metal block structure formed at the end of the electrode fingers of the interdigital transducer;

[0042] Figure 7 It is Figure 6A schematic cross-sectional view of the surface acoustic wave resonator shown, where the raised metal block and the end edge of the electrode finger are not vertically aligned;

[0043] Figure 8 For Figure 6 Another schematic cross-sectional view of the surface acoustic wave resonator shown, where the raised metal block and the end edge of the electrode finger are not vertically aligned;

[0044] Figure 9 A schematic structural diagram of a surface acoustic wave resonator provided by an embodiment of the present application;

[0045] Figure 10 For Figure 9 A schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the AA' section;

[0046] Figure 11 A simulation test result diagram of a surface acoustic wave resonator provided by an embodiment of the present application and an existing surface acoustic wave resonator;

[0047] Figure 12 A simulation test result diagram of the surface acoustic wave resonator provided by an embodiment of the present application at different depths H of the piezoelectric layer embedded in the part where the interdigital transducer is embedded in the piezoelectric layer;

[0048] Figure 13 For Figure 9 A schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the CC' section;

[0049] Figure 14 For Figure 9 Another schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the CC' section;

[0050] Figure 15 For Figure 9 Another schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the CC' section;

[0051] Figure 16 For Figure 9 Another schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the CC' section;

[0052] Figure 17 For Figure 9 Another schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the CC' section;

[0053] Figure 18 For Figure 9 Another schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the CC' section;

[0054] Figure 19 For Figure 9Another schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the AA' section;

[0055] Figure 20 It is a simulation test result diagram of two surface acoustic wave resonators provided in the embodiments of the present application, where an adhesive layer is provided and not provided between the part of the interdigital transducer embedded in the piezoelectric layer and the piezoelectric layer;

[0056] Figure 21 It is a top view schematic diagram of a surface acoustic wave resonator provided in the embodiments of the present application;

[0057] Figure 22 is Figure 9 Another schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the AA' section;

[0058] Figure 23 is Figure 9 Another schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the AA' section;

[0059] Figure 24 is Figure 9 Another schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the AA' section;

[0060] Figure 25 is Figure 9 Another schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the AA' section;

[0061] Figure 26 It is a simulation test result diagram of two surface acoustic wave resonators provided in the embodiments of the present application, where chamfers are provided and not provided on the electrode fingers when each electrode finger of the interdigital transducer is embedded in the piezoelectric layer;

[0062] Figure 27 It is a top view schematic diagram of another surface acoustic wave resonator provided in the embodiments of the present application;

[0063] Figure 28 It is a simulation test result diagram of the dummy fingers of the surface acoustic wave resonator provided in the embodiments of the present application at different lengths. Detailed implementation manners

[0064] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0065] In the description, claims and the above-mentioned drawings of this application, terms such as "first" and "second" are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances, which is only a way of distinguishing objects with the same attributes when describing the embodiments of this application. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, so that a process, method, system, product or device including a series of units does not have to be limited to those units, but may include other units not clearly listed or inherent to these processes, methods, products or devices.

[0066] Secondly, this application is described in detail in combination with schematic diagrams. When describing the embodiments of this application in detail, for the convenience of explanation, the drawings showing the device structure will be enlarged locally out of the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of this application here. In addition, in actual production, three-dimensional spatial dimensions including length, width and depth should be included.

[0067] As described in the background art section, how to effectively suppress the spurious waves of surface acoustic wave resonators, improve the Q value of the resonators, and comprehensively improve the performance of surface acoustic wave resonators is a technical problem that those skilled in the art urgently need to solve.

[0068] Currently, in order to suppress the spurious waves of surface acoustic wave resonators and improve the performance of the resonators, the industry has adopted a variety of technical solutions. For example, the applicant has previously applied for a design using an inclined interdigital transducer and a design of forming a Piston structure (piston structure) at the ends of the electrode fingers of the interdigital transducer.

[0069] Among them, when using the design of an inclined interdigital transducer to suppress in-band spurious, reference can be specifically made to the invention patent with the patent number CN114614794A applied by the applicant earlier, and its brief structural schematic diagram is as Figure 1 shown, the invention patent with the patent number CN114710134A, and its brief structural schematic diagram is as Figure 2 shown, and the invention patent with the patent number CN117375564A, and its brief structural schematic diagram is as Figure 3 shown, combined with Figures 1 - 3 shown, the interdigital transducer includes busbars 011, busbars 012, and electrode fingers 013 and dummy fingers 014 located between the busbars 011 and busbars 012. Reflection gratings 02 are also provided on both sides of the interdigital transducer. The busbars 011 and busbars 012 adopt a zigzag structure. Specifically, the busbars 011 and busbars 012 are inclined at a certain angle with respect to the propagation direction X0 of the main acoustic mode, so as to reduce the transverse resonance mode and improve the suppression effect of the resonator on spurious waves.

[0070] However, the inventors have found through research that when the design of an inclined interdigital transducer is adopted to suppress spurious waves, although the larger the inclination angle of the bus bar relative to the propagation direction of the main acoustic mode, the better the suppression effect on spurious waves, when the inclination angle exceeds a certain angle, it will instead lead to a decrease in the Q value, electromechanical coupling coefficient, and effective area of the surface acoustic wave resonator, thus causing a contradiction between suppressing spurious waves and improving the Q value, electromechanical coupling coefficient, and effective area of the resonator.

[0071] Exemplarily, Figure 4 FIG. shows a top view schematic diagram of a surface acoustic wave resonator having an inclined interdigital transducer, as Figure 4 shown, the bus bar 011 and the bus bar 012 are arranged in parallel, and the included angle between the extending direction of the bus bar 011 and the bus bar 012 and the propagation direction X0 of the main acoustic mode is the inclination angle theta of the bus bar 011 and the bus bar 012. Figure 5 FIG. shows Figure 4 the simulation test result diagram of the surface acoustic wave resonator shown, as Figure 5 shown, when the inclination angle theta of the bus bar 011 and the bus bar 012 is 7 deg, the left side of the resonance peak is smooth, but the spurious suppression on the right side of the resonance peak is incomplete. If the inclination angle theta of the bus bar 011 and the bus bar 012 is continuously increased to smooth the in-band, for example, the inclination angle theta of the bus bar 011 and the bus bar 012 is increased to 10 deg, but from Figure 5 it can be seen that although the right side of the resonance peak with the inclination angle theta = 10 deg is smoother than that with the inclination angle theta = 7 deg, the overall curve with the inclination angle theta = 10 deg is worse, which usually leads to a decrease in the Q value, electromechanical coupling coefficient, and effective area of the resonator.

[0072] Thus, it can be seen that when achieving the best spurious wave suppression effect by inclining the bus bar, the corresponding optimal inclination angle theta of the bus bar is usually too large, which will instead lead to a decrease in the Q value, electromechanical coupling coefficient, and effective area of the resonator.

[0073] When the design of forming a Piston structure at the end of the electrode fingers of the interdigital transducer is adopted to suppress in-band spurious, specifically as Figure 6 shown, it is necessary to form a widened and thickened raised metal block structure 015 (i.e., the Piston structure) in the shape of a hammer head at the end of the electrode finger 013. Since the raised metal block structure 015 and the electrode finger 013 are usually two metal layers and not an integral metal layer, therefore, it may bring additional process problems. For example, as Figure 7 shown, the raised metal block structure 015 is closer to the inner side of the electrode finger than the end edge of the electrode finger 013, forming a structure similar to a step; for another example, as Figure 8As shown, the raised metal block structure 015 is closer to the outer side of the electrode finger 013 than the end edge of the electrode finger 013, forming a structure similar to an eave or a bridge. This will bring about different effects on the suppression of stray waves, thus causing a decrease in the Q value of the resonator.

[0074] In summary, when the current surface acoustic wave resonator uses the design of the tilted interdigital transducer and the design of forming a Piston structure at the end of the electrode finger to suppress stray waves, the suppression effect on stray waves is not ideal, which often affects the improvement of the Q value of the resonator and even causes a decrease in the Q value of the resonator, affecting the overall performance of the resonator.

[0075] In view of this, an embodiment of the present application provides a surface acoustic wave resonator. Figure 9 The structural schematic diagram of a surface acoustic wave resonator provided by an embodiment of the present application is shown. Figure 10 As shown Figure 9 A schematic cross-sectional structure diagram of the surface acoustic wave resonator along the AA' section is shown. Combining Figure 9 and Figure 10 As shown, the surface acoustic wave resonator includes a substrate 10, a piezoelectric layer 20 located on one side of the substrate 10, and an interdigital transducer 30 at least partially embedded in the piezoelectric layer 20 from the side of the piezoelectric layer 20 facing away from the substrate 10.

[0076] Among them, combining Figure 9 and Figure 10 As shown, the interdigital transducer 30 includes a first bus bar 31 and a second bus bar 32 arranged oppositely. Between the first bus bar 31 and the second bus bar 32, there are electrode fingers 33 connected to the first bus bar 31 and electrode fingers 33 connected to the second bus bar 32. The electrode fingers 33 connected to the first bus bar 31 and the electrode fingers 33 connected to the second bus bar 32 are alternately arranged along the first direction X. The electrode fingers 33 extend along the second direction Y. 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 are perpendicular.

[0077] Combining Figure 9 and Figure 10 As shown, at least part of the electrode fingers 33 of the interdigital transducer 30 are embedded in the piezoelectric layer 20, and in the direction perpendicular to the plane where the substrate 10 is located, the depth H of the part of the interdigital transducer 30 embedded in the piezoelectric layer 20 embedded in the piezoelectric layer 20 is not less than 0.02λ, that is, H≥0.02λ, where λ is the wavelength of the acoustic wave propagating in the surface acoustic wave resonator.

[0078] It can be understood that the first direction X is the propagation direction of the main acoustic mode of the surface acoustic wave resonator, and is also the direction in which the electrode fingers 33 connected to the first bus bar 31 and the electrode fingers 33 connected to the second bus bar 32 are alternately arranged; the second direction Y is the extending direction of the electrode fingers 33.

[0079] In the embodiment of the present application, the interdigital transducer 30 is entirely located on the side of the piezoelectric layer 20 away from the substrate 10, and at least a part of the interdigital transducer 30 is embedded in the piezoelectric layer 20. Specifically, at least a part of the electrode fingers 33 of the interdigital transducer 30 is embedded in the piezoelectric layer 20. At this time, the part of the interdigital transducer 30 embedded in the piezoelectric layer 20 at least includes part of the electrode fingers 33. Further optionally, each of the electrode fingers 33 of the interdigital transducer 30 can be embedded in the piezoelectric layer 20. At this time, the part of the interdigital transducer 30 embedded in the piezoelectric layer 20 at least includes each of the electrode fingers 33. Further optionally, the entire interdigital transducer 30 is embedded in the piezoelectric layer 20. At this time, the first bus bar 31, the second bus bar 32 and each of the electrode fingers 33 of the interdigital transducer 30 are all embedded in the piezoelectric layer 20.

[0080] During specific operation, the surface acoustic wave resonator can realize the conversion between electrical energy and mechanical energy. Optionally, when an alternating electrical signal is applied to the interdigital transducer 30, a periodically distributed electric field will be generated on the piezoelectric layer 20. Due to the inverse piezoelectric effect of the piezoelectric layer 20, this electric field will excite corresponding elastic deformations near the surface of the piezoelectric layer 20. This elastic deformation will cause the vibration of the solid particles, forming a surface acoustic wave propagating along the surface of the piezoelectric layer 20. Another option is that when the surface acoustic wave propagates to the surface of the piezoelectric layer 20, due to the direct piezoelectric effect of the piezoelectric layer 20, charges can be induced in the interdigital transducer 30, thereby forming an alternating electrical signal output.

[0081] It can be understood from this that compared with the interdigital transducer in the existing surface acoustic wave resonator being located on the surface of the piezoelectric layer away from the substrate, in the surface acoustic wave resonator provided by the embodiment of the present application, by embedding at least a part of the electrode fingers 33 of the interdigital transducer 30 in the piezoelectric layer 20, on the one hand, it is beneficial for the piezoelectric layer 20 to realize the efficient conversion between electrical energy and mechanical energy through the piezoelectric effect, reducing energy loss. On the other hand, it makes the combination of the piezoelectric layer 20 and the interdigital transducer 30 more stable, thereby effectively suppressing the spurious waves of the surface acoustic wave resonator, significantly weakening the in-band spurious of the surface acoustic wave resonator, and further improving the Q value of the resonator, comprehensively improving the performance of the surface acoustic wave resonator.

[0082] To verify the above results, Figure 11 The simulation test result diagrams of a surface acoustic wave resonator (H = 0.02λ) provided by the embodiment of the present application and an existing surface acoustic wave resonator (H = 0) are shown. Among them, in the surface acoustic wave resonator provided by the embodiment of the present application, the depth H of the part of the interdigital transducer 30 embedded in the piezoelectric layer 20 embedded in the piezoelectric layer 20 is 0.02λ, where λ is the wavelength of the acoustic wave propagating in the surface acoustic wave resonator; in the existing surface acoustic wave resonator, the interdigital transducer is located on the surface of the piezoelectric layer, that is, the interdigital transducer is not embedded in the piezoelectric layer, and it can be considered that the depth H of the interdigital transducer embedded in the piezoelectric layer is 0; from Figure 11It can be clearly seen that, compared with the design in which the interdigital transducer in the existing surface acoustic wave resonator is not embedded in the piezoelectric layer, in the embodiment of the present application, at least part of the electrode fingers 33 of the interdigital transducer 30 are embedded in the piezoelectric layer 20, so that the in-band spurs of the surface acoustic wave resonator are significantly weakened, thereby the Q value of the surface acoustic wave resonator can be improved, and further the performance of the surface acoustic wave resonator can be comprehensively improved.

[0083] Among them, Figure 11 Taking the case where each electrode finger 33 of the interdigital transducer 30 is embedded in the piezoelectric layer 20 as an example, the specific parameters of the surface acoustic wave resonator are as follows: the thickness t_idt of the interdigital transducer 30 is 0.34 μm, the thickness t_LT / LN of the piezoelectric layer 20 is 0.75 μm, the wavelength λ of the acoustic wave propagating in the surface acoustic wave resonator is 4.4 μm, the duty cycle eta is 0.5, and the length of the overlapping part of the electrode fingers 33 connected to the first bus bar 31 and the electrode fingers 33 connected to the second bus bar 32 along the first direction X, which is also called the aperture AP, is 15λ.

[0084] The inventor further studied the performance of the surface acoustic wave resonator at different depths H of the piezoelectric layer 20 embedded in the part of the interdigital transducer 30 embedded in the piezoelectric layer 20. Figure 12 FIG. shows the simulation test result diagrams of the surface acoustic wave resonator provided by the embodiment of the present application at different depths H of the piezoelectric layer 20 embedded in the part of the interdigital transducer 30 embedded in the piezoelectric layer 20, where H = 0, 0.02λ, 0.06λ, and 0.77λ. H = 0 corresponds to the case where each electrode finger 33 of the interdigital transducer 30 is not embedded in the piezoelectric layer 20, H = 0.02λ corresponds to the depth H = 0.02λ of the piezoelectric layer 20 embedded in the part of the interdigital transducer 30 embedded in the piezoelectric layer 20, H = 0.06λ corresponds to the depth H = 0.06λ of the piezoelectric layer 20 embedded in the part of the interdigital transducer 30 embedded in the piezoelectric layer 20, and H = 0.77λ corresponds to the case where the part of the interdigital transducer 30 embedded in the piezoelectric layer 20 is just completely embedded in the piezoelectric layer 20. From Figure 12 It can be seen that as the depth H of the piezoelectric layer 20 embedded in the part of the interdigital transducer 30 embedded in the piezoelectric layer 20 increases, the in-band spurs of the surface acoustic wave resonator are significantly weakened. Although when the part of the interdigital transducer 30 embedded in the piezoelectric layer 20 is completely embedded in the piezoelectric layer 20 (corresponding to H = 0.77λ), the in-band spurs slightly increase, they are still weaker than the in-band spurs when each electrode finger 33 of the interdigital transducer 30 is not embedded in the piezoelectric layer 20 (corresponding to H = 0); and as the depth H of the piezoelectric layer 20 embedded in the part of the interdigital transducer 30 embedded in the piezoelectric layer 20 increases, the operating frequency of the resonator gradually rises, and it can be applied to higher frequency scenarios. Figure 12 Among them, taking the case where each electrode finger 33 of the interdigital transducer 30 is embedded in the piezoelectric layer 20, the other parameters of the surface acoustic wave resonator are the same as Figure 11The corresponding parameters of the medium surface acoustic wave resonator are the same and will not be elaborated here.

[0085] It can be understood from this that in the surface acoustic wave resonator provided by the embodiments of the present application, not only at least part of the electrode fingers 33 of the interdigital transducer 30 are embedded in the piezoelectric layer 20, but also in the direction Z perpendicular to the plane where the substrate 10 is located, the depth H of the part of the interdigital transducer 30 embedded in the piezoelectric layer 20 embedded in the piezoelectric layer 20 is not less than 0.02λ, that is, H≥0.02λ, where λ is the wavelength of the acoustic wave propagating in the surface acoustic wave resonator, so that the in-band spurs of the surface acoustic wave resonator are significantly weakened, the Q value of the surface acoustic wave resonator is effectively improved, and the performance of the surface acoustic wave resonator is overall improved.

[0086] Further optionally, it is also possible to set the depth H of the part of the interdigital transducer 30 embedded in the piezoelectric layer 20 embedded in the piezoelectric layer 20 to be not greater than 0.06λ in the direction Z perpendicular to the plane where the substrate 10 is located, that is, 0.02λ≤H≤0.06λ, where λ is the wavelength of the acoustic wave propagating in the surface acoustic wave resonator, so as to further significantly weaken the in-band spurs of the surface acoustic wave resonator, effectively improve the Q value of the surface acoustic wave resonator, and overall improve the performance of the surface acoustic wave resonator.

[0087] Optionally, the substrate 10 can be a Si substrate, and the material of the piezoelectric layer 20 includes but is not limited to lithium tantalate (LiTaO 3 ), lithium niobate (LiNbO 3 ), etc.

[0088] Optionally, as shown in Figure 9 and Figure 10 , a high sound velocity layer 40 and a low sound velocity layer 50 can also be provided between the substrate 10 and the piezoelectric layer 20. The sound velocity of the high sound velocity layer 40 is greater than that of the low sound velocity layer 50. In this way, the high sound velocity layer 40 and the low sound velocity layer 50 can form a sound velocity gradient to better confine the energy in the piezoelectric layer 20, improve the Q value of the surface acoustic wave resonator, and have no influence on the transverse mode. Among them, the high sound velocity layer 40 can be a polysilicon layer, and the low sound velocity layer 50 can be a silicon dioxide layer. Optionally, the thickness t_SiO 2 of the low sound velocity layer 50 is 0.625μm, and the thickness t_PolySi of the high sound velocity layer 40 is 1μm.

[0089] It can be understood that when all the electrode fingers 33 of the interdigital transducer 30 are embedded in the piezoelectric layer 20, the energy loss can be further reduced, and the combination of the piezoelectric layer 20 and the interdigital transducer 30 will be more stable, so that the in-band spurs of the surface acoustic wave resonator can be further weakened, the Q value of the surface acoustic wave resonator can be improved, and the performance of the surface acoustic wave resonator can be comprehensively improved.

[0090] When each electrode finger 33 of the interdigital transducer 30 is embedded in the piezoelectric layer 20, optionally, as Figure 13 shown, Figure 13 shows Figure 9 a schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the CC' section. It can be seen that the depth H of each electrode finger 33 of the interdigital transducer 30 embedded in the piezoelectric layer 20 can be the same. In this way, while reducing the in-band spurs of the surface acoustic wave resonator and improving the Q value of the surface acoustic wave resonator, the manufacturing process can be simplified. It is only necessary to etch a groove with a uniform depth on the surface of the piezoelectric layer 20 facing away from the substrate 10, and then form the electrode fingers 33 in the groove, and the pattern of the groove is the same as that of the electrode fingers 33.

[0091] When each electrode finger 33 of the interdigital transducer 30 is embedded in the piezoelectric layer 20, another option is, as Figures 14 - 17 shown, Figures 14 - 17 shows Figure 9 four other schematic cross-sectional structure diagrams of the surface acoustic wave resonator shown along the CC' section. It can be seen that the depths H of at least two adjacent electrode fingers 33 of the interdigital transducer 30 adjacent to each other along the first direction X embedded in the piezoelectric layer 20 are different. In this way, two adjacent electrode fingers 33 with different depths embedded in the piezoelectric layer 20 can form a sound velocity gradient in the piezoelectric layer 20 to better confine the energy in the piezoelectric layer 20 and improve the Q value of the surface acoustic wave resonator, and it has no influence on the transverse mode. However, the manufacturing process will be relatively more complex.

[0092] Further optionally, as Figure 14 shown, along the first direction X, the depth H of each electrode finger 33 of the interdigital transducer 30 embedded in the piezoelectric layer 20 gradually increases.

[0093] Another further option is, as Figure 15 shown, along the first direction X, the depth H of each electrode finger 33 of the interdigital transducer 30 embedded in the piezoelectric layer 20 gradually decreases.

[0094] Another further option is, as Figure 16 shown, along the first direction X, the depth H of each electrode finger 33 of the interdigital transducer 30 embedded in the piezoelectric layer 20 first increases and then decreases, that is, the depth H of each electrode finger 33 of the interdigital transducer 30 embedded in the piezoelectric layer 20 changes in a V shape.

[0095] Another further option is, as Figure 17 shown, along the first direction X, the depth H of each electrode finger 33 of the interdigital transducer 30 embedded in the piezoelectric layer 20 first decreases and then increases, that is, the depth H of each electrode finger 33 of the interdigital transducer 30 embedded in the piezoelectric layer 20 changes in an inverted V shape.

[0096] It can be understood that, as Figures 14 - 17As shown, the depths H at which any two adjacent electrode fingers 33 of the interdigital transducer 30 are embedded in the piezoelectric layer 20 along the first direction X can be different. In this way, any two adjacent electrode fingers 33 can form a sound velocity gradient in the piezoelectric layer 20, so as to further better confine the energy in the piezoelectric layer 20, improve the Q value of the surface acoustic wave resonator, and have no influence on the transverse mode.

[0097] It can also be understood that along the first direction X, the depth H at which each electrode finger 33 of the interdigital transducer 30 is embedded in the piezoelectric layer 20 first increases and then decreases or first decreases and then increases. Compared with the case where the depth H at which each electrode finger 33 of the interdigital transducer 30 is embedded in the piezoelectric layer 20 gradually increases or gradually decreases, it is beneficial to the symmetry of the interdigital transducer structure, and thus beneficial to improving the performance of the surface acoustic wave resonator.

[0098] It should be noted that in Figures 13 - 17 , the thicknesses of the respective electrode fingers 33 in the interdigital transducer 30 are the same as an example for display. Then, if the depths H at which two electrode fingers 33 are embedded in the piezoelectric layer 20 are different and the thicknesses of the two electrode fingers 33 are the same, the surfaces of the two electrode fingers 33 facing away from the substrate 10 may not be in the same plane. Optionally, the thicknesses of the electrode fingers 33 with different depths H embedded in the piezoelectric layer 20 can also be set to be different, so that even if the depths H at which different electrode fingers 33 are embedded in the piezoelectric layer 20 are different, the surfaces of the different electrode fingers 33 facing away from the substrate 10 can still be in the same plane.

[0099] It should also be noted that in Figures 13 - 17 , the case where each electrode finger 33 in the interdigital transducer 30 is completely embedded in the piezoelectric layer 20 at most is taken as an example for display, that is, the surface of the electrode finger 33 facing away from the substrate 10 is at most flush with the surface of the piezoelectric layer 20 facing away from the substrate 10. However, the present application is not limited thereto. Optionally, the surface of the electrode finger 33 facing away from the substrate 10 can also be lower than the surface of the piezoelectric layer 20 facing away from the substrate 10.

[0100] It should be further noted that since the electrode finger 33 is embedded into the piezoelectric layer 20 from the side of the piezoelectric layer 20 facing away from the substrate 10, therefore, regardless of the degree of embedding of the electrode finger 33 into the piezoelectric layer 20, the depth H at which the electrode finger 33 is embedded in the piezoelectric layer 20 refers to the distance between the surface of the piezoelectric layer 20 facing away from the substrate 10 and the surface of the electrode finger 33 close to the substrate 10.

[0101] Considering the convenience of the manufacturing process, the entire interdigital transducer 30 can also be embedded in the piezoelectric layer 20, and the depth at which the entire interdigital transducer 30 is embedded in the piezoelectric layer 20 is the same. In this way, the pattern of the groove on the surface of the piezoelectric layer 20 facing away from the substrate 10 is the same as the pattern of the interdigital transducer 30, which is convenient for the manufacturing process.

[0102] Another option is Figure 18 illustratesFigure 9 Another schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the CC' section, as Figure 18 shown, a part of the electrode fingers 33 of the interdigital transducer 30 are embedded in the piezoelectric layer 20, another part of the electrode fingers 33 of the interdigital transducer 30 are not embedded in the piezoelectric layer 20, and the electrode fingers 33 embedded in the piezoelectric layer 20 and the electrode fingers 33 not embedded in the piezoelectric layer 20 in the interdigital transducer 30 are arranged alternately. In this way, any two adjacent electrode fingers 33 can also form a sound velocity gradient in the piezoelectric layer 20 to further better confine the energy in the piezoelectric layer 20, improve the Q value of the surface acoustic wave resonator, and have no influence on the transverse mode. Among them, the depth H of each electrode finger 33 of the interdigital transducer 30 embedded in the piezoelectric layer 20 can be the same or partially different, depending on the specific situation.

[0103] Figure 19 shows Figure 9 Another schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the AA' section, as Figure 19 shown, optionally, in the direction Z perpendicular to the plane of the substrate 10, a bonding layer 60 is provided between the part of the interdigital transducer 30 embedded in the piezoelectric layer 20 and the piezoelectric layer 20. The bonding layer 60 can make the combination between the interdigital transducer 30 and the groove of the piezoelectric layer 20 closer, further enhance the structural stability of the surface acoustic wave resonator, and thus further improve the overall performance of the resonator.

[0104] Optionally, as Figure 19 shown, in the direction Z perpendicular to the plane of the substrate 10, the thickness d of the bonding layer 60 is not greater than 20 nm, that is, d ≤ 20 nm.

[0105] Optionally, the material of the bonding layer 60 can include at least one of Ti metal and AlTi alloy, that is, the material of the bonding layer 60 can be Ti metal, or AlTi alloy, or include Ti metal and AlTi alloy.

[0106] As Figure 19 shown, the bonding layer 60 is mainly provided between the bottom of the groove of the piezoelectric layer 20 and the electrode fingers 33. Of course, the bonding layer 60 can also be provided between the side wall of the groove of the piezoelectric layer 20 and the electrode fingers 33, which can make the combination between the interdigital transducer 30 and the groove of the piezoelectric layer 20 closer. However, since the thickness of the piezoelectric layer 20 is relatively thin, the depth of the groove of the piezoelectric layer 20 is also relatively small. When the bonding layer 60 is formed in the groove of the piezoelectric layer 20, the bonding layer 60 will be mainly distributed at the bottom of the groove of the piezoelectric layer 20.

[0107] Figure 20The figure shows the simulation test result diagrams of two surface acoustic wave resonators provided by the embodiments of the present application, where an adhesive layer 60 (d = 20 nm) is provided between the part of the interdigital transducer 30 embedded in the piezoelectric layer 20 and the piezoelectric layer 20, and no adhesive layer 60 (d = 0) is provided. From Figure 20 It can be seen that compared with not providing the adhesive layer 60 between the part of the interdigital transducer 30 embedded in the piezoelectric layer 20 and the piezoelectric layer 20, it can be considered that the thickness d of the adhesive layer 60 is 0. After providing the adhesive layer 60 between the part of the interdigital transducer 30 embedded in the piezoelectric layer 20 and the piezoelectric layer 20, for example, when the thickness d of the adhesive layer 60 is 20 nm, the in-band spurs of the surface acoustic wave resonator are further weakened. In particular, the spurs on the left side of the resonance peak are significantly improved, thereby bringing about a further increase in the Q value of the surface acoustic wave resonator. Figure 20 In the figure, taking each electrode finger 33 of the interdigital transducer 30 being embedded in the piezoelectric layer 20 and the embedding depth H = 0.06λ as an example, the other parameters of the surface acoustic wave resonator are the same as those of the surface acoustic wave resonator in Figure 11 and will not be elaborated here.

[0108] As known from the foregoing, when achieving the best spurious wave suppression effect by tilting the interdigital transducer, specifically by tilting the bus bar, the optimal tilt angle theta of the bus bar relative to the main acoustic mode propagation direction is usually too large, which will instead lead to a decrease in the Q value, electromechanical coupling coefficient, and effective area of the resonator. In the embodiments of the present application, since at least part of the electrode fingers 33 of the interdigital transducer 30 can be embedded in the piezoelectric layer 20 to achieve the purpose of suppressing spurious waves and increasing the Q value of the resonator, therefore, as Figure 21 shown, Figure 21 The figure shows a top view schematic diagram of a surface acoustic wave resonator provided by the embodiments of the present application. It can be seen that the extension direction of at least one of the first bus bar 31 and the second bus bar 32 in the interdigital transducer 30 can be further set to have an included angle theta with the first direction X, that is, at least one of the first bus bar 31 and the second bus bar 32 in the interdigital transducer 30 is tilted relative to the main acoustic mode propagation direction (i.e., the first direction X), and the tilt angle theta can be less than the optimal tilt angle, thereby avoiding the decrease in the Q value, electromechanical coupling coefficient, and effective area of the resonator due to the too large optimal tilt angle of the first bus bar 31 and / or the second bus bar 32. Moreover, the suppression effect of spurious waves by embedding at least part of the electrode fingers 33 of the interdigital transducer 30 in the piezoelectric layer 20 and the suppression effect of spurious waves by tilting the first bus bar 31 and / or the second bus bar 32 can be superimposed, so as to combine and realize suppressing the spurious waves of the resonator effectively while reducing the influence on the Q value, electromechanical coupling coefficient, and effective area of the resonator, and comprehensively improving the performance of the resonator.

[0109] It can be understood that at least one of the first bus bar 31 and the second bus bar 32 in the interdigital transducer 30 is inclined relative to the propagation direction of the main acoustic mode (i.e., the first direction X). Optionally, the first bus bar 31 in the interdigital transducer 30 is inclined at a certain angle relative to the first direction X; alternatively, the second bus bar 32 in the interdigital transducer 30 is inclined at a certain angle relative to the first direction X; further alternatively, both the first bus bar 31 and the second bus bar 32 in the interdigital transducer 30 are inclined at a certain angle relative to the first direction X, and the angle at which the first bus bar 31 is inclined relative to the first direction X and the angle at which the second bus bar 32 is inclined relative to the first direction X may be equal or may not be equal.

[0110] Figure 22 and Figure 23 show Figure 9 Another two schematic cross-sectional structure diagrams of the surface acoustic wave resonator shown along the AA' section are shown in, for example, Figure 22 and Figure 23 shown. In order to improve the power resistance (also known as the electrical resistance) of the electrode fingers 33, the electrode fingers 33 may be provided to include two metal layers, that is, the electrode fingers 33 include a first metal layer M1 and a second metal layer M2 stacked in sequence along the direction away from the substrate 10. Among them, the first metal layer M1 may serve as the main electrode finger layer, and the second metal layer M2 may serve as the electrode pad layer. If the electrode fingers 33 are embedded in the piezoelectric layer 20, the interface between the first metal layer M1 and the second metal layer M2 in the electrode fingers 33 is preferably not coincident with the surface of the piezoelectric layer 20 away from the substrate 10. Optionally, as shown in Figure 22 shown, the interface between the first metal layer M1 and the second metal layer M2 in the electrode fingers 33 is located on the side of the surface of the piezoelectric layer 20 away from the substrate 10 that is far from the substrate 10; or, alternatively, as shown in Figure 23 shown, the interface between the first metal layer M1 and the second metal layer M2 in the electrode fingers 33 is located on the side of the surface of the piezoelectric layer 20 away from the substrate 10 that is close to the substrate 10.

[0111] It can be understood that the acoustic wave propagates on the surface of the piezoelectric layer 20 away from the substrate 10. Setting the interface between the first metal layer M1 and the second metal layer M2 in the electrode fingers 33 not to coincide with the surface of the piezoelectric layer 20 away from the substrate 10 can reduce the vibration of the acoustic wave at the interface between the first metal layer M1 and the second metal layer M2 in the electrode fingers 33, which is beneficial to improving the structural stability of the electrode fingers 33, and thus can improve the reliability and performance of the surface acoustic wave resonator.

[0112] It can also be understood that, by comparing Figure 22 and Figure 23It can be known that setting the interface between the first metal layer M1 and the second metal layer M2 in the electrode finger 33 on the side close to the substrate 10 on the surface of the piezoelectric layer 20 facing away from the substrate 10 can further improve the structural stability of the electrode finger 33 compared with setting it on the side far from the substrate 10 on the surface of the piezoelectric layer 20 facing away from the substrate 10.

[0113] Figure 24 shows Figure 9 Another schematic cross-sectional structure diagram of the AA' cross-section in the surface acoustic wave resonator shown, as Figure 24 shown, in a plane perpendicular to the second direction Y, that is, in a plane perpendicular to the extending direction of the electrode finger 33, the cross-section of the electrode finger 33 can be trapezoidal, and the length of the bottom side of the trapezoid close to the substrate 10 is greater than the length of the bottom side of the trapezoid away from the substrate 10, that is, the trapezoid is a regular trapezoid. Optionally, as Figure 24 shown, the value range of the two bottom angles beta corresponding to the bottom side of the trapezoid close to the substrate 10 can be 70° - 90°, including the end values.

[0114] Figure 25 shows Figure 9 Another schematic cross-sectional structure diagram of the surface acoustic wave resonator shown along the AA' cross-section, as Figure 25 shown, in a plane perpendicular to the second direction Y, that is, in a plane perpendicular to the extending direction of the electrode finger 33, the cross-section of the electrode finger 33 can be rectangular, the two corners of the rectangle away from the substrate 10 are rounded corners, and the two corners of the rectangle close to the substrate 10 are right angles, or rather, the two corners of the rectangle away from the substrate 10 are chamfered. Denote the curvature radius of the chamfer as R. It can be understood that the curvature radius R of the chamfer is negatively correlated with the depth H of the electrode finger 33 embedded in the piezoelectric layer 20, that is, the greater the depth H of the electrode finger 33 embedded in the piezoelectric layer 20, the less the part of the electrode finger 33 exposed from the piezoelectric layer 20, and the smaller the curvature radius R of the chamfer. On the contrary, the smaller the depth H of the electrode finger 33 embedded in the piezoelectric layer 20, the more the part of the electrode finger 33 exposed from the piezoelectric layer 20, and the larger the curvature radius R of the chamfer can be. Preferably, the curvature radius R of the chamfer can be equal to the thickness of the part of the electrode finger 33 exposed from the piezoelectric layer 20, and the curvature radius R of the chamfer is not greater than 0.164 μm.

[0115] Figure 26 shows the simulation test result diagrams in two cases where each electrode finger 33 of the interdigital transducer 30 in the surface acoustic wave resonator provided by the embodiment of the present application is embedded in the piezoelectric layer 20 and the depth H of embedding in the piezoelectric layer 20 is 0.06λ, with the electrode finger 33 having a chamfer with a curvature radius R = 76 nm and without a chamfer (R = 0), from Figure 26It can be seen that when chamfers are provided on the electrode fingers 33, since the weight of the electrode fingers 33 can be slightly reduced, the resonance frequency of the resonator slightly increases, enabling it to adapt to higher-frequency scenarios, and moreover, it does not affect the suppression effect on in-band spurs. Figure 26 Other parameters of the intermediate surface acoustic wave resonator are the same as Figure 11 the corresponding parameters of the intermediate surface acoustic wave resonator, which will not be elaborated herein.

[0116] It can be understood that whether the cross-sectional shape of the electrode fingers 33 in the plane perpendicular to the second direction Y is set as a trapezoid or a rectangle with chamfers, the weight of the electrode fingers 33 can be slightly reduced, thereby causing the resonance frequency of the resonator to slightly increase, enabling it to adapt to higher-frequency scenarios, and moreover, it does not affect the suppression effect on in-band spurs.

[0117] Figure 27 Fig. shows a top view schematic diagram of another surface acoustic wave resonator provided by an embodiment of the present application. As Figure 24 shown, dummy fingers 34 connected to the first bus bar 31 and dummy fingers 34 connected to the second bus bar 32 are further provided between the first bus bar 31 and the second bus bar 32. The dummy fingers 34 connected to the first bus bar 31 and the electrode fingers 33 connected to the second bus bar 32 are arranged oppositely along the second direction Y. The dummy fingers 34 connected to the second bus bar 32 and the electrode fingers 33 connected to the first bus bar 31 are arranged oppositely along the second direction Y. Moreover, the electrode fingers 33 and the dummy fingers 34 connected to the first bus bar 31 are alternately arranged along the first direction X, and the electrode fingers 33 and the dummy fingers 34 connected to the second bus bar 32 are alternately arranged along the first direction X. With such an arrangement, the lateral mode can be reflected by the sound velocity mutation boundary in the dummy finger region, avoiding the formation of resonance conditions, further suppressing the spurious waves of the resonator, and achieving better resonator performance. Among them, the extending direction of the dummy fingers 34 is the same as that of the electrode fingers 33, and along the extending direction of the dummy fingers 34, the length of the dummy fingers 34 is dum.

[0118] It can be understood that while at least some of the electrode fingers 33 in the interdigital transducer 30 are embedded in the piezoelectric layer 20, at least some of the dummy fingers 34 can also be embedded in the piezoelectric layer 20.

[0119] Taking the example that each of the electrode fingers 33 and each of the dummy fingers 34 in the interdigital transducer 30 are embedded in the piezoelectric layer 20 and the embedding depth in the piezoelectric layer 20 is the same, the inventor studied the length dum of the dummy fingers 34 in the interdigital transducer 30. Figure 28 Fig. shows a simulation test result diagram of the dummy fingers 34 in the surface acoustic wave resonator provided by an embodiment of the present application under different lengths dum. From Figure 28It can be seen that, compared with not setting dummy fingers, i.e., dum = 0, after setting the dummy fingers 34, when dum = 0.5λ, 1λ or 1.5λ, the in-band spurs of the resonator are further reduced. In particular, when the length dum of the dummy fingers is between 0.5λ - 1.5λ, the in-band spur suppression effect of the resonator is better. Therefore, preferably, it can be set that along the extension direction of the dummy fingers 34, the value range of the length dum of the dummy fingers 34 is 0.5λ - 1.5λ, including the end values, where λ is the wavelength of the acoustic wave propagating in the surface acoustic wave resonator, so that the resonator has a higher Q value and better overall performance.

[0120] Correspondingly, an embodiment of the present application further provides a filter, including the surface acoustic wave resonator provided in any of the above embodiments.

[0121] Furthermore, an embodiment of the present application further provides an electronic device, including the above filter.

[0122] Since the surface acoustic wave resonator has been described in detail in the foregoing embodiments, it will not be elaborated herein.

[0123] In this specification, each part is described in a combined manner of parallel and progressive. The key point of each part is to illustrate the differences from other parts. For the same or similar parts among each part, reference can be made to each other.

[0124] Regarding the above description of the disclosed embodiments, the features recorded in each embodiment of this specification can be replaced or combined with each other, enabling those skilled in the art to implement or use the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A surface acoustic wave resonator, characterized in that: include: substrate; a piezoelectric layer located on one side of the substrate; An interdigital transducer at least partially embedded in the piezoelectric layer from a side of the piezoelectric layer facing away from the substrate; The interdigital transducer includes a first bus bar and a second bus bar that are arranged opposite to each other, and electrode fingers connected to the first bus bar and electrode fingers connected to the second bus bar are arranged between the first bus bar and the second bus bar, and the electrode fingers connected to the first bus bar and the electrode fingers connected to the second bus bar are alternately arranged along a first direction, and the electrode fingers extend along a second direction, and 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 are perpendicular; at least part of the electrode fingers of the interdigital transducer are embedded in the piezoelectric layer, and in a direction perpendicular to the plane where the substrate is located, the depth of the part of the interdigital transducer embedded in the piezoelectric layer is not less than 0.02λ, where λ is the wavelength of the sound wave propagating in the surface acoustic wave resonator.

2. The surface acoustic wave resonator according to claim 1, characterized in that: Each of the electrode fingers of the interdigital transducer is embedded in the piezoelectric layer.

3. The surface acoustic wave resonator according to claim 2, characterized in that: The electrode fingers of the interdigital transducer are embedded in the piezoelectric layer to the same depth.

4. The surface acoustic wave resonator according to claim 2, characterized in that: At least two electrode fingers adjacent to each other along the first direction in the IDT are embedded in the piezoelectric layer at different depths.

5. The surface acoustic wave resonator according to claim 4, characterized in that: Along the first direction, the depth at which each electrode finger of the interdigital transducer is embedded in the piezoelectric layer gradually increases; Alternatively, along the first direction, the depth at which each electrode finger of the interdigital transducer is embedded in the piezoelectric layer gradually decreases; Alternatively, along the first direction, the depth at which each electrode finger of the IDT is embedded in the piezoelectric layer increases first and then decreases; Alternatively, along the first direction, the depth at which each electrode finger of the IDT is embedded in the piezoelectric layer first decreases and then increases.

6. The surface acoustic wave resonator according to claim 1, characterized in that: Part of the electrode fingers of the IDT are embedded in the piezoelectric layer, and another part of the electrode fingers of the IDT are not embedded in the piezoelectric layer. In addition, the electrode fingers embedded in the piezoelectric layer and the electrode fingers not embedded in the piezoelectric layer in the IDT are alternately arranged.

7. The surface acoustic wave resonator according to claim 1, characterized in that: In a direction perpendicular to the plane where the substrate is located, a depth at which a portion of the interdigital transducer embedded in the piezoelectric layer is embedded in the piezoelectric layer is no more than 0.06λ.

8. The surface acoustic wave resonator according to claim 1, characterized in that: In a direction perpendicular to the plane where the substrate is located, an adhesive layer is arranged between a portion of the interdigital transducer embedded in the piezoelectric layer and the piezoelectric layer.

9. The surface acoustic wave resonator according to claim 8, characterized in that: In a direction perpendicular to the plane where the substrate is located, the thickness of the adhesive layer is no more than 20 nm.

10. The surface acoustic wave resonator according to claim 8, characterized in that: The material of the adhesive layer includes at least one of Ti metal and AlTi alloy.

11. The surface acoustic wave resonator according to claim 1, characterized in that: An extending direction of at least one of the first bus bar and the second bus bar has an included angle with the first direction.

12. The surface acoustic wave resonator according to claim 1, characterized in that: The electrode finger includes a first metal layer and a second metal layer stacked in sequence in a direction away from the substrate, and an interface between the first metal layer and the second metal layer in the electrode finger does not overlap with a surface of the piezoelectric layer away from the substrate.

13. The surface acoustic wave resonator according to claim 1, characterized in that: In a plane perpendicular to the second direction, the cross section of the electrode finger is trapezoidal, and the length of the bottom edge of the trapezoid close to the substrate is greater than the length of the bottom edge of the trapezoid away from the substrate.

14. The surface acoustic wave resonator according to claim 13, characterized in that: The value range of the two bottom angles corresponding to the bottom edge of the trapezoid close to the substrate is 70°-90°, including the endpoint values.

15. The surface acoustic wave resonator according to claim 1, characterized in that: In a plane perpendicular to the second direction, the cross section of the electrode finger is rectangular, two corners of the rectangle facing away from the substrate are rounded, and two corners of the rectangle close to the substrate are right angles.

16. The surface acoustic wave resonator according to claim 1, characterized in that: A dummy finger connected to the first bus bar and a dummy finger connected to the second bus bar are also provided between the first bus bar and the second bus bar, the dummy finger connected to the first bus bar and the electrode finger connected to the second bus bar are arranged opposite to each other along the second direction, and the dummy finger connected to the second bus bar and the electrode finger connected to the first bus bar are arranged opposite to each other along the second direction; Along the extension direction of the pseudo finger, the length of the pseudo finger ranges from 0.5λ to 1.5λ, including the endpoint values.

17. A filter, characterized in that: The surface acoustic wave resonator comprises the surface acoustic wave resonator according to any one of claims 1 to 16.

18. An electronic device, characterized in that: Comprising the filter as claimed in claim 17.

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