Surface acoustic wave device and electronic module

Abstract

The embodiment of the invention provides a surface acoustic wave device and an electronic module. The surface acoustic wave device comprises a piezoelectric substrate and an IDT electrode, and the IDT electrode is located on one side of the piezoelectric substrate. The IDT electrode includes: bus bars including a first bus bar and a second bus bar facing each other in a first direction; the first bus bar is provided with a plurality of first electrode fingers and a plurality of first dummy electrode fingers, and the first electrode fingers and the first dummy electrode fingers are alternately arranged and extend from the first bus bar to the second bus bar; the second bus bar is provided with a plurality of second electrode fingers and a plurality of second dummy electrode fingers, and the second electrode fingers and the second dummy electrode fingers are alternately arranged and extend from the second bus bar to the first bus bar; the edge of one end, close to the second bus bar, of at least one first dummy electrode finger is provided with an inward groove; and / or the edge of one end, close to the first bus bar, of at least one second dummy electrode finger is provided with an inward groove.

Description

Surface acoustic wave devices and electronic modules Technical Field

[0001] This invention relates to the field of semiconductor technology, and more particularly to a surface acoustic wave device and an electronic module. Background Technology

[0002] With the rapid development of internet technology and the continuous innovation of the communications industry, the widespread application of next-generation communication technologies such as 5G is driving communication systems towards higher speeds, lower latency, and larger capacity, placing more stringent demands on the performance indicators of radio frequency (RF) front-end devices. Surface acoustic wave (SAW) filters, as a core component of the RF front-end, have been widely used in various electronic devices such as mobile terminals and communication base stations due to their miniaturization, high reliability, and excellent adjacent-channel suppression performance, playing an irreplaceable role in isolating interference signals and ensuring the stability of communication links.

[0003] With the increasing complexity of communication systems, signal transmission environments are becoming more complex, placing higher demands on the in-band clutter suppression capabilities of SAW filters. The presence of in-band transverse clutter directly leads to decreased filter flatness and uneven signal attenuation, severely impacting communication quality and transmission efficiency, becoming a key bottleneck restricting further performance improvements of SAW filters. Currently, the clutter suppression levels of existing SAW devices are insufficient to meet the high-precision signal purity requirements of next-generation communication technologies.

[0004] Therefore, how to effectively suppress clutter modes in surface acoustic wave (SAW) devices and improve in-band clutter suppression capability has become a pressing technical problem in the field of SAW device technology. Summary of the Invention

[0005] Therefore, in order to overcome at least some of the defects and deficiencies in the prior art, embodiments of the present invention provide a surface acoustic wave device and an electronic module.

[0006] Specifically, in one aspect, the surface acoustic wave device provided in the embodiments of the present invention includes: a piezoelectric substrate and an IDT electrode, wherein the IDT electrode is located on one side of the piezoelectric substrate; the IDT electrode includes: a bus bar, including a first bus bar and a second bus bar, which are opposite to each other along a first direction; a plurality of first electrode fingers and a plurality of first dummy electrode fingers are provided on the first bus bar, the first electrode fingers and the first dummy electrode fingers are alternately arranged, and extend from the first bus bar to the second bus bar; a plurality of second electrode fingers and a plurality of second dummy electrode fingers are provided on the second bus bar, the second electrode fingers and the second dummy electrode fingers are alternately arranged, and extend from the second bus bar to the first bus bar; at least one of the first dummy electrode fingers has an inwardly recessed groove at its edge near one end of the second bus bar; and / or, at least one of the second dummy electrode fingers has an inwardly recessed groove at its edge near one end of the first bus bar.

[0007] In one specific embodiment of the present invention, the first dummy electrode finger is provided with one or more first openings spaced apart along the first direction; the second dummy electrode finger is provided with one or more second openings spaced apart along the first direction.

[0008] In one specific embodiment of the present invention, the first opening has an arcuate wall with its arcuate curvature center pointing toward the second busbar, and the second opening has an arcuate wall with its arcuate curvature center pointing toward the first busbar.

[0009] In one specific embodiment of the present invention, the first opening and the second opening have the same shape, which is an arc, a crescent, a semi-ellipse, or a semi-circle.

[0010] In a specific embodiment of the present invention, the arc shape of the arc wall satisfies the following function: y=a*sin(b*x), where y is the length of the arc wall along the direction of the finger arrangement, x is the width of the arc wall along the first direction, and a and b are constants, where a is 1~5 and b is 0.1~10.

[0011] In one specific embodiment of the present invention, the first opening has two symmetrically arranged and connected straight arms, the opening formed by the two straight arms faces the second busbar, and the included angle between the two straight arms is 100°~170°; the second opening has two symmetrically arranged and connected straight arms, the opening formed by the two straight arms faces the first busbar, and the included angle between the two straight arms is 100°~170°.

[0012] In one specific embodiment of the present invention, the ratio of the depth of the first opening to the thickness of the IDT electrode is 10% to 100%, and the ratio of the depth of the second opening to the thickness of the IDT electrode is 10% to 100%.

[0013] In one specific embodiment of the present invention, the ratio of the depth of the first opening to the thickness of the IDT electrode is 30% to 80%, and the ratio of the depth of the second opening to the thickness of the IDT electrode is 30% to 80%.

[0014] In one specific embodiment of the present invention, a plurality of first openings are arranged periodically, the period length being 0.1λ~0.2λ; a plurality of second openings are arranged periodically, the period length being 0.1λ~0.2λ, where λ is the elastic wave wavelength of the surface acoustic wave device.

[0015] In a specific embodiment of the present invention, the first dummy electrode includes a first opening region, a plurality of first openings are disposed in the first opening region, and the first opening region accounts for 30% to 90% of the first dummy electrode; the second dummy electrode includes a second opening region, a plurality of second openings are disposed in the second opening region, and the second opening region accounts for at least 30% to 90% of the second dummy electrode.

[0016] In one specific embodiment of the present invention, the first opening extends to a portion of the first busbar, and the second opening extends to a portion of the second busbar.

[0017] In one specific embodiment of the present invention, the thickness of the piezoelectric substrate is in the range of 0.1λ to 0.4λ, and the thickness of the IDT electrode is in the range of 0.03λ to 0.2λ, where λ is the elastic wave wavelength of the surface acoustic wave device.

[0018] In one specific embodiment of the present invention, the width of the first opening is less than or equal to 80% of the width of the first dummy electrode finger, and the width of the second opening is less than or equal to 80% of the width of the second dummy electrode finger; or, in the width direction of the first electrode finger, the two sides of the first opening are spaced apart from the edge of the first electrode finger, and the two sides of the second opening are spaced apart from the edge of the second electrode finger, wherein the interval is greater than or equal to 10% of the width of the dummy electrode finger.

[0019] On the other hand, embodiments of the present invention also provide an electronic module including the surface acoustic wave device as described above.

[0020] As can be seen from the above, the surface acoustic wave device provided in this embodiment of the invention includes a piezoelectric substrate and an IDT electrode. The IDT electrode includes a first bus bar, a second bus bar, a first electrode finger, a first dummy electrode finger, a second electrode finger, and a second dummy electrode finger. By having an inward groove on the edge of the first dummy electrode finger near the second bus bar and an inward groove on the edge of the second dummy electrode finger near the first bus bar, the grooves effectively reduce the lateral scattering of sound waves at the edge of the dummy electrode finger, significantly enhancing the in-band lateral clutter suppression effect. At the same time, the grooves can match the flat elliptical propagation shape of sound waves, which can constrain the sound energy to concentrate on a preset path on the surface of the piezoelectric substrate, reducing the radiation and leakage of energy to the outside of the piezoelectric substrate and improving the energy utilization rate of electroacoustic conversion. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 is a top view of a surface acoustic wave (SAW) device according to an embodiment of the present invention; Figure 2 is a cross-sectional view of the SAW device in Figure 1 along section AA; Figure 3 is a top view of another SAW device according to an embodiment of the present invention; Figure 4 is a cross-sectional view of the SAW device in Figure 3 along section AA; Figure 5A is an admittance characteristic curve of a SAW device in the prior art; Figure 5B is an admittance characteristic curve of the SAW device in this embodiment; Figures 6 to 9 are schematic diagrams of various structures of the SAW device according to an embodiment of the present invention; Figure 10 is a schematic diagram of the structure of the first dummy electrode finger in the SAW device according to an embodiment of the present invention; Figure 11 is another schematic diagram of the structure of the first dummy electrode finger; Figure 12 is yet another schematic diagram of the structure of the first dummy electrode finger.

[0023] Key component designations: 10, piezoelectric substrate; 20, IDT electrode; 110, first busbar; 120, second busbar; 210, first dummy electrode finger; 211, first opening; 2111, straight arm; 220, first electrode finger; 310, second dummy electrode finger; 311, second opening; 320, second electrode finger; 201, groove; 202, first opening region; 301, second opening region; x, first direction; y, second direction; D, interval; L, period length. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments described in the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0025] It should be noted that all directional indicators (such as up, down, left, right, front, back, top, and bottom) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of the components in a specific posture (as shown in the attached figures). If the specific posture changes, the directional indicator will also change accordingly. Furthermore, the term "vertical" used in the embodiments and claims refers to an angle of 90° between two components or a deviation of -5° to +5°, and the term "parallel" refers to an angle of 0° between two components or a deviation of -5° to +5°.

[0026] In the embodiments of this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0027] Referring to Figures 1 and 2, this embodiment of the invention provides a surface acoustic wave (SAW) device, including a piezoelectric substrate 10 and an interdigital transducer (IDT) electrode 20, the IDT electrode 20 being located on one side of the piezoelectric substrate 10. Specifically, the piezoelectric substrate 10 may be made of lithium tantalate, lithium niobate, or quartz; for example, in some embodiments, the piezoelectric substrate 10 is made of lithium tantalate. The IDT electrode 20, or interdigital transducer, is used to convert electrical signals into sound waves for transmission or reception to determine the resonant frequency and bandwidth. The IDT electrode 20 is located on one side of the piezoelectric substrate 10, specifically on the upper surface of the piezoelectric substrate 10. The IDT electrode 20 includes, but is not limited to, one or more of the following alloys: Al, Cu, Pt, Au, and Ti.

[0028] The IDT electrode 20 includes a busbar, which includes a first busbar 110 and a second busbar 120. The first busbar 110 and the second busbar 120 are opposite to each other along a first direction x. The first busbar 110 is provided with a plurality of first electrode fingers 220 and a plurality of first dummy electrode fingers 210, which are alternately arranged and extend from the first busbar 110 toward the second busbar 120. The second busbar 120 is provided with a plurality of second electrode fingers 320 and a plurality of second dummy electrode fingers 310, which are alternately arranged and extend from the second busbar 120 toward the first busbar 110.

[0029] At least one first dummy electrode finger 210 has an inwardly facing groove 201 at its edge near the end of the second busbar 120; and / or at least one second dummy electrode finger 310 has an inwardly facing groove 201 at its edge near the end of the first busbar 110. By providing an inwardly facing groove 201 at the edge of the end of the dummy electrode finger, the groove 201 can be, for example, an arc-shaped structure, a zigzag structure, etc., with the opening of the groove 201 facing the busbar on the opposite side. Thus, the groove 201 can effectively reduce the lateral scattering of sound waves at the edge of the dummy electrode finger, greatly enhancing the lateral noise suppression effect within the band. At the same time, the opening can match the flat elliptical propagation shape of the sound wave, which can constrain the sound energy to concentrate on a preset path on the surface of the piezoelectric substrate 10, reduce the radiation and leakage of energy to the outside of the piezoelectric substrate 10, and improve the energy utilization rate of electroacoustic conversion.

[0030] Referring to Figures 3 and 4, in the embodiment shown in Figure 3, in addition to the groove 201 present in the above embodiments, one or more first openings 211 are provided at intervals along the first direction x on the first dummy electrode finger 210; one or more second openings 311 are provided at intervals along the first direction x on the second dummy electrode finger 310. Specifically, the number and morphology of the first openings 211 and the second openings 311 are completely identical. The first openings 211 and the second openings 311 are also presented in a groove shape on the dummy electrode finger.

[0031] The surface acoustic wave (SAW) device provided in this embodiment of the invention includes a piezoelectric substrate 10 and an IDT electrode 20. The IDT electrode 20 includes a first bus bar 110, a second bus bar 120, a first electrode finger 220, a first dummy electrode finger 210, a second electrode finger 320, and a second dummy electrode finger 310. One or more first openings 211 are provided at intervals along a first direction x on the first dummy electrode finger 210, and one or more second openings 311 are provided at intervals along the first direction x on the second dummy electrode finger 310. By constructing multiple additional openings, the lateral scattering of sound waves at the edge of the dummy electrode finger is further effectively reduced, and the noise waves not suppressed by the groove 201 are further suppressed, forming a second barrier and significantly enhancing the lateral noise suppression effect within the band. At the same time, the openings can match the flat elliptical propagation shape of the sound waves, which can constrain the sound energy to concentrate on a preset path on the surface of the piezoelectric substrate 10, reduce the radiation and leakage of energy to the outside of the piezoelectric substrate 10, and improve the energy utilization rate of electroacoustic conversion. Furthermore, the concentrated utilization of energy and precise suppression of clutter can make the filter's stopband suppression effect more significant and the passband steepness better. This is beneficial to improving the rectangularity of the filter, thereby enabling a more comprehensive improvement in the signal purity, energy efficiency and operational stability of surface acoustic wave devices, making them more suitable for the high-performance requirements of RF devices in communication technologies such as 5G.

[0032] Referring to Figures 5A and 5B, Figure 5A shows the admittance characteristic curve of a surface acoustic wave (SAW) device in the prior art; Figure 5B shows the admittance characteristic curve of the SAW device in this embodiment. As shown in Figure 5A, a strong clutter peak appears near 1040MHz; clutter fluctuations occur near 1080MHz; the overall curve fluctuates significantly, and the in-band flatness is poor. This indicates that the existing SAW device exhibits significant clutter interference within the target frequency band. As shown in Figure 5B, the clutter peak near 1040MHz is significantly suppressed; the clutter fluctuations near 1080MHz almost disappear; the overall curve is smoother, and the in-band flatness is significantly improved. Compared to the comparative example, the SAW device provided in this embodiment significantly enhances the suppression capability of in-band transverse clutter, significantly deepens the attenuation of clutter, reduces curve fluctuations, and significantly improves clutter suppression performance.

[0033] In this embodiment, the thickness of the piezoelectric substrate 10 ranges from 0.1λ to 0.4λ, and the thickness of the IDT electrode 20 ranges from 0.03λ to 0.2λ, where λ is the elastic wave wavelength of the surface acoustic wave device, and the Euler angle is (0°, 42°, 0°). Within this thickness and Euler angle range, a large electromechanical coupling coefficient and a high Q value can be excited, while the in-band clutter is small.

[0034] Referring again to Figure 3, in one embodiment of this example, the first opening 211 has an arc-shaped wall with its arc curvature center pointing towards the second busbar, and the second opening 311 has an arc-shaped wall with its arc curvature center pointing towards the first busbar. In the IDT electrode 20, the arc-shaped wall curvature center of the first opening 211 points towards the second busbar 120, and the arc-shaped wall curvature center of the second opening 311 points towards the first busbar 110, forming a bidirectional directional acoustic guiding structure. This structure can precisely constrain the surface acoustic waves to converge towards the effective working area of ​​the IDT electrode 20, preventing acoustic energy from radiating and leaking towards the busbar. Therefore, it can significantly suppress clutter excitation in the busbar region, enhance the full-area suppression effect of transverse clutter in the band, and improve the concentration of acoustic energy in the effective working area, thus optimizing the energy utilization rate of electroacoustic conversion. In addition, because the directional curvature of the arc-shaped wall achieves a smooth transition of acoustic impedance, it further improves the in-band flatness of the filter.

[0035] Furthermore, the arc shape of the arc wall satisfies the following function: y = a*sin(b*x), where y is the length of the arc wall along the direction of the finger arrangement, and x is the width of the arc wall along the first direction x, as shown in Figure 1. The direction of the finger arrangement (the second direction) is the y direction, and the first direction is the x direction. a and b are constants, where a is 1~5 and b is 0.1~10. For example, a can be 1, 1.2, 1.5, 1.8, 2, 3, 3.1, 3.2, 4, 4.5, or 5, and b can be 0.1, 0.2, 0.3, 0.5, 0.67, 0.8, 0.93, 1, 2, 3, 4, 5, 6, 6.3, 7, 7.1, 8, 9, 9.5, 9.8, or 10. Of course, this embodiment is not limited to these values. Preferably, a is 1.55 and b is 0.63.

[0036] Because this sinusoidal function shape can accurately match the flattened elliptical propagation mode of surface acoustic waves, it can effectively reduce the lateral scattering of sound waves in the curved wall region, thus significantly enhancing the suppression effect of in-band lateral clutter. At the same time, the continuous and smooth characteristics of the sine curve realize the gradual transition of acoustic impedance, avoiding the outward radiation of acoustic energy caused by abrupt boundary changes, thereby improving the concentrated utilization rate of acoustic energy in the effective working area. In addition, this standardized sinusoidal function shape also improves the process compatibility of structural processing, reduces the impact of production deviations on performance, and ultimately achieves synergistic optimization of the clutter suppression capability, energy conversion efficiency and process stability of SAW filters, enabling them to better adapt to the stringent performance requirements of RF front-end devices for communication technologies such as 5G.

[0037] In one embodiment of this invention, the first opening 211 and the second opening 311 have the same shape, which is an arc, crescent, semi-ellipse, or semi-circle. In the embodiment shown in FIG1, the first opening 211 and the second opening 311 are crescent-shaped; in the embodiment shown in FIG3, the first opening 211 and the second opening 311 are arc-shaped; and in the embodiment shown in FIG6, the first opening 211 and the second opening 311 are semi-ellipse. Of course, this is merely illustrative and is not intended to be limiting.

[0038] Referring to Figure 7, in one embodiment of this invention, the first opening 211 has two symmetrically arranged and connected straight arms 2111, the opening formed by the two straight arms 2111 faces the second busbar 120, and the included angle between the two straight arms 2111 is 100°~170°; the second opening 311 has two symmetrically arranged and connected straight arms 2111, the opening formed by the two straight arms 2111 faces the first busbar 110, and the included angle between the two straight arms 2111 is 100°~170°.

[0039] As shown in Figure 7, the first opening 211 and the second opening 311 can have the same broken line structure. Taking the first opening 211 as an example, the first opening 211 includes two straight arms 2111. The two straight arms 2111 are symmetrically arranged and inclined. One end of the two straight arms 2111 is connected to each other, and the other end extends to the edge of the finger strip in opposite directions. By the inclined arrangement of the two straight arms 2111, an angle is formed at the connection point of the two straight arms 2111. For example, the angle between the two straight arms 2111 can be 100°, 101°, 105°, 110°, 111°, 120°, 125°, 130°, 140°, 150°, 160°, 166°, or 170°, etc. Of course, this embodiment is not limited to this. Preferably, the angle between the two straight arms is 110°~160°.

[0040] The first opening 211 adopts a symmetrical straight arm structure with the opening facing the second busbar 120, and the second opening 311 adopts a symmetrical straight arm structure with the opening facing the first busbar 110. The angle between the two straight arms is set to 100°~170°. Since the symmetrical arm structure can directionally constrain the propagation direction of the sound wave, it can guide the sound energy to converge in the effective working area of ​​the IDT electrode 20 and avoid the sound energy from radiating and leaking to the busbar area, thus improving the energy utilization rate of electroacoustic conversion. At the same time, the symmetrical straight arm structure with a suitable angle can reduce the scattering of sound waves near the busbar, thereby greatly suppressing the excitation of clutter in this area and strengthening the full-area suppression effect of transverse clutter in the band.

[0041] In one embodiment of this invention, the width of the first opening 211 is less than or equal to 80% of the width of the first dummy electrode finger 210, and the width of the second opening 311 is less than or equal to 80% of the width of the second dummy electrode finger 310. It should be noted that, in the width direction of the electrode finger, i.e., the second direction Y, the two sides of the first opening 211 are spaced apart from the edge of the first electrode finger 210, and the two sides of the second opening 311 are spaced apart from the edge of the second electrode finger 310. That is, the edges of the graphic grooves in the second direction Y do not contact the edges of the electrode fingers. This spaced design preserves the structural integrity of the electrode finger edges, avoids the influence of the grooves on the electrical conductivity of the electrode fingers, and balances acoustic noise suppression with electrical performance stability.

[0042] In another embodiment of this invention, in the width direction of the first electrode finger 210, i.e., in the second direction Y, the two sides of the first opening 211 are spaced apart from the edge of the first electrode finger 210, and the two sides of the second opening 311 are spaced apart from the edge of the second electrode finger 310. The interval D is greater than or equal to 10% of the width of the dummy electrode finger. This spacing design preserves the structural integrity of the electrode finger edge, avoids the influence of the groove on the electrical conductivity of the electrode finger, and balances acoustic clutter suppression with electrical performance stability. In this embodiment, the two intervals formed by the two sides of the graphic groove and the edge of the electrode finger can, for example, be the same or different.

[0043] In this embodiment, multiple first openings 211 are spaced apart along a first direction x, and multiple second openings 311 are spaced apart along the first direction x. As shown in Figure 7, specifically, the multiple first openings 211 can be arranged periodically, with a period length L of 0.1λ~0.2λ; the multiple second openings 311 can also be arranged periodically, with a period length L of 0.1λ~0.2λ. λ is the elastic wave wavelength of the surface acoustic wave device, which can specifically be 2~5μm, and the period length is 0.2~1μm. The period length L can be understood as the spacing between corresponding positions of adjacent acoustic impedance pattern grooves, for example, the distance between the vertices of two adjacent acoustic impedance pattern grooves.

[0044] Because the period length precisely matches the propagation period characteristics of surface acoustic waves, a uniform and continuous acoustic impedance distribution can be formed in the virtual region of the IDT electrode 20, avoiding acoustic wave scattering caused by local impedance abrupt changes. This further enhances the global suppression effect of transverse clutter within the band. At the same time, the periodically arranged groove structure can directionally guide acoustic energy to propagate along a preset path, reducing the radiation leakage of acoustic energy to the busbar or the outside of the substrate, thereby improving the energy utilization rate of electroacoustic conversion. In addition, the uniform periodic structure makes the signal attenuation in the passband more consistent, the attenuation in the stopband more thorough, and the transition band between the passband and the stopband steeper, which is beneficial to improving the rectangularity of the filter. Furthermore, the standardized periodic design improves the consistency of structural processing and process compatibility, reducing the impact of production deviations on performance.

[0045] As shown in Figure 8, the first dummy electrode finger 210 includes a first opening region 202, and a plurality of first openings 211 are disposed in the first opening region 202. The first opening region 202 occupies 30% to 90% of the first dummy electrode finger 210. Specifically, the first opening region 202 may, for example, occupy 30%, 35%, 40%, 50%, 60%, 65%, 70%, 80%, 90%, etc. of the first dummy electrode finger 210. The second dummy electrode finger 310 includes a second opening region 301, and a plurality of second openings 311 are disposed in the second opening region 301. The second opening region 301 occupies at least 30% to 90% of the second dummy electrode finger 310. Specifically, the second opening region 301 occupies at least 30%, 35%, 40%, 50%, 60%, 65%, 70%, 80%, 90%, etc. of the second dummy electrode finger 310. In this embodiment, the first opening region 202 and the second opening region 301 have the same size. The opening region can be divided, for example, by making a horizontal tangent on the dummy electrode finger along the first direction at the furthest point from the connected busbar, and making a horizontal tangent at the closest point to the connected busbar. The area of ​​the dummy electrode finger between the two horizontal tangents is the opening region.

[0046] The first dummy electrode 210 has a first opening region 202 that occupies 30%~90% of the area, and the second dummy electrode 310 has a second opening region 301 that occupies 30%~90% of the area. Each region has multiple openings. Since this percentage range can be flexibly adjusted according to device performance requirements (from partial to complete coverage), it can adapt to the acoustic impedance optimization needs of different scenarios. Increasing the percentage allows for a uniform transition of acoustic impedance distribution across the entire domain, while a moderate percentage balances performance and processing costs. Therefore, it can comprehensively suppress acoustic wave scattering in all regions of the dummy electrode, enhancing the overall suppression effect of transverse clutter within the band. Furthermore, a reasonable coverage range can constrain acoustic energy to concentrate in the effective working area, reducing energy leakage to the busbar or substrate exterior and improving electroacoustic conversion efficiency. Simultaneously, the standardized 30%~90% percentage design considers process feasibility, avoiding insufficient performance due to excessive coverage and avoiding increased processing difficulty due to over-design, ensuring production consistency and cost control. Moreover, the uniformly covered groove area makes the attenuation difference between the passband and stopband more significant, further optimizing the filter's rectangularity.

[0047] As shown in Figure 9, in some embodiments of this example, the first opening 211 extends to a portion of the first busbar 110, and the second opening 311 extends to a portion of the second busbar 120. By extending the first opening 211 to a portion of the first busbar 110 and the second opening 311 to a portion of the second busbar 120, the impedance pattern grooves extending to the busbars can form a global acoustic constraint structure, preventing acoustic energy from radiating and leaking at the edges of the busbars, thereby improving the concentrated utilization rate of acoustic energy in the effective working area. Furthermore, the suppression of clutter and energy concentration in the connection area between the electrode fingers and the busbars further enhance the stability of the filter's passband signal and the thoroughness of its stopband attenuation, resulting in a steeper transition between the passband and stopband, which is beneficial for optimizing the filter's rectangularity.

[0048] In this embodiment, the ratio of the depth of the first opening 211 to the thickness of the IDT electrode 20 is 10% to 100%, and the ratio of the depth of the second opening 311 to the thickness of the IDT electrode 20 is also 10% to 100%. Since this ratio range can precisely match the acoustic impedance characteristics of the IDT electrode 20 and the piezoelectric substrate 10, it achieves gradient control of the acoustic impedance. This avoids insufficient impedance adjustment caused by a ratio that is too small (<10%), and also prevents acoustic propagation problems caused by a ratio that is too large (>100%, damaging the piezoelectric substrate 10). Therefore, it can effectively reduce the reflection and scattering of sound waves in the groove region, further enhancing the suppression effect of transverse clutter within the band. Simultaneously, the depth of the opening adapted to the thickness of the IDT electrode 20 can form a stronger acoustic constraint, firmly locking the acoustic energy within the effective working area, reducing the leakage of acoustic energy into the substrate or towards the busbar direction, and significantly improving the electroacoustic conversion efficiency. Furthermore, the ratio of the depth of the first opening 211 to the thickness of the IDT electrode 20 is 30% to 80%, and the ratio of the depth of the second opening 311 to the thickness of the IDT electrode 20 is also 30% to 80%. Setting the ratio of the opening depth to the thickness of the IDT electrode 20 to 30% to 80% avoids damage to the surface of the piezoelectric substrate 10 when the opening is too deep during the formation process, and also avoids the effect of too shallow a depth. The ratio range of 30% to 80% takes into account both the feasibility of process fabrication and structural stability, avoiding increased processing difficulty or reduced device reliability caused by extreme dimensions.

[0049] In one embodiment of this example, as shown in Figure 10, multiple first openings 211 have the same depth, and multiple second openings 311 have the same depth. Furthermore, the depth of the first openings 211 and the depth of the multiple second openings 311 are the same. It should be noted that the same depth here is not limited to being completely identical; the depths of different first openings 211 and second openings 311 can have an error value of ±3%. Having multiple openings of the same depth allows for a uniform acoustic impedance distribution in the virtual region, avoiding local impedance abrupt changes caused by depth differences, reducing scattering interference during sound wave propagation, and thus further enhancing the global uniform suppression effect of transverse clutter within the band. Simultaneously, the uniform groove depth ensures consistent acoustic constraint strength, more stably locking acoustic energy within the effective working area, reducing energy leakage, and improving the consistency and efficiency of electroacoustic conversion. In addition, the unified depth design reduces the difficulty of dimensional control during processing, improves the compatibility of the manufacturing process and product consistency, avoids the discrete impact of depth deviation on device performance, and the uniform acoustic impedance transition makes the passband attenuation smoother and the stopband attenuation more thorough, which is beneficial for optimizing the rectangularity of the filter.

[0050] Referring to Figures 11 and 12, among the multiple first openings 211, the depth of the first first opening 211 closest to the second busbar 120 is greater than the depth of the other first openings 211; among the multiple second openings 311, the depth of the first second opening 311 closest to the first busbar 110 is greater than the depth of the other second openings 311. By maximizing the depth of the openings at the ends of the virtual region, the acoustic constraint of the critical region can be precisely strengthened, thus significantly improving the directional suppression effect of in-band transverse clutter.

[0051] Furthermore, the depths of the multiple first openings 211 and the depths of the multiple second openings 311 are different. For example, the depths of the multiple first openings 211 may be completely different, and the depths of the multiple second openings 311 may be completely different. Alternatively, some of the multiple first openings 211 may have the same depth, while others may have different depths; similarly, some of the multiple second openings 311 may have the same depth, while others may have different depths. The acoustic impedance transition at different depths makes the attenuation difference between the passband and stopband more significant, and the transition band steeper, which is beneficial for further optimizing the rectangularity of the filter. Moreover, this design achieves performance upgrades only by adjusting the depth of local grooves without adding complex structures, thus balancing the feasibility of manufacturing processes and product consistency.

[0052] As shown in Figure 11, in one embodiment of this example, the depth of the plurality of first openings 211 gradually increases along the direction from the first busbar 110 to the second busbar 120, and the depth of the plurality of second openings 311 gradually increases along the direction from the second busbar 120 to the first busbar 110. Because the depth of multiple impedance pattern grooves is continuously gradient, a continuous gradient acoustic impedance distribution that precisely matches the sound wave propagation path is constructed. This can suppress sound wave scattering in different regions from the source, especially enhancing the clutter suppression effect in high-risk areas near the busbar. Therefore, it significantly improves the global continuous suppression capability of transverse clutter within the band. At the same time, the depth-gradient structure forms a directional acoustic guiding force, guiding acoustic energy to converge smoothly from the side of the busbar to the effective working area, thereby significantly improving the energy utilization and stability of electroacoustic conversion. In addition, the continuously gradient acoustic impedance transition makes the signal attenuation in the passband more uniform, the attenuation in the stopband more thorough, and the transition band between the passband and the stopband steeper. This is conducive to further optimizing the rectangularity of the filter. Moreover, this design does not require additional complex structures, but achieves performance upgrades only through depth gradient, taking into account the feasibility of manufacturing processes and product consistency.

[0053] This invention also provides an electronic module including the surface acoustic wave device described above. The electronic module of this embodiment possesses all the technical effects of the surface acoustic wave device, which will not be elaborated further here.

[0054] Furthermore, it is understood that the foregoing embodiments are merely illustrative examples of the present invention. Provided that the technical features do not conflict, the structure is not contradictory, and the purpose of the invention is not violated, the technical solutions of the various embodiments can be arbitrarily combined and used.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A surface acoustic wave device, characterized in that, include: A piezoelectric substrate and an IDT electrode, wherein the IDT electrode is located on one side of the piezoelectric substrate; The IDT electrode includes: a bus bar, including a first bus bar and a second bus bar, which are opposite to each other along a first direction; The first busbar is provided with a plurality of first electrode fingers and a plurality of first dummy electrode fingers, the first electrode fingers and the first dummy electrode fingers are alternately arranged and extend from the first busbar toward the second busbar; the second busbar is provided with a plurality of second electrode fingers and a plurality of second dummy electrode fingers, the second electrode fingers and the second dummy electrode fingers are alternately arranged and extend from the second busbar toward the first busbar; at least one of the first dummy electrode fingers has an inwardly recessed groove at its edge near one end of the second busbar; and / or, at least one of the second dummy electrode fingers has an inwardly recessed groove at its edge near one end of the first busbar.

2. The surface acoustic wave device as described in claim 1, characterized in that, in, The first dummy electrode finger has one or more first openings spaced apart along the first direction; the second dummy electrode finger has one or more second openings spaced apart along the first direction.

3. The surface acoustic wave device as described in claim 2, characterized in that, The first opening has an arc-shaped wall with its center of curvature pointing towards the second busbar, and the second opening has an arc-shaped wall with its center of curvature pointing towards the first busbar.

4. The surface acoustic wave device as described in claim 3, characterized in that, The first opening and the second opening have the same shape, which is an arc, crescent, semi-ellipse or semi-circle.

5. The surface acoustic wave device as described in claim 3, characterized in that, The arc shape of the arc wall satisfies the following function: y=a*sin(b*x), where y is the length of the arc wall along the direction of the finger arrangement, x is the width of the arc wall along the first direction, and a and b are constants, where a is 1~5 and b is 0.1~10.

6. The surface acoustic wave device as described in claim 2, characterized in that, The first opening has two symmetrically arranged and connected straight arms, the opening formed by the two straight arms faces the second busbar, and the included angle between the two straight arms is 100°~170°; the second opening has two symmetrically arranged and connected straight arms, the opening formed by the two straight arms faces the first busbar, and the included angle between the two straight arms is 100°~170°.

7. The surface acoustic wave device as described in claim 2, characterized in that, The ratio of the depth of the first opening to the thickness of the IDT electrode is 10% to 100%, and the ratio of the depth of the second opening to the thickness of the IDT electrode is 10% to 100%.

8. The surface acoustic wave device as described in claim 7, characterized in that, The ratio of the depth of the first opening to the thickness of the IDT electrode is 30% to 80%, and the ratio of the depth of the second opening to the thickness of the IDT electrode is 30% to 80%.

9. The surface acoustic wave device as described in claim 2, characterized in that, The plurality of first openings are arranged periodically, with a period length of 0.1λ to 0.2λ; the plurality of second openings are arranged periodically, with a period length of 0.1λ to 0.2λ, where λ is the elastic wave wavelength of the surface acoustic wave device.

10. The surface acoustic wave device as described in claim 2, characterized in that, The first dummy electrode includes a first opening region, with a plurality of first openings disposed in the first opening region, and the first opening region accounting for 30% to 90% of the first dummy electrode; the second dummy electrode includes a second opening region, with a plurality of second openings disposed in the second opening region, and the second opening region accounting for 30% to 90% of the second dummy electrode.

11. The surface acoustic wave device as described in claim 2, characterized in that, The first opening extends to a portion of the first busbar, and the second opening extends to a portion of the second busbar.

12. The surface acoustic wave device as described in claim 1, characterized in that, The thickness of the piezoelectric substrate ranges from 0.1λ to 0.4λ, and the thickness of the IDT electrode ranges from 0.03λ to 0.2λ, where λ is the elastic wave wavelength of the surface acoustic wave device.

13. The surface acoustic wave device as described in claim 2, characterized in that, The width of the first opening is less than or equal to 80% of the width of the first dummy electrode finger, and the width of the second opening is less than or equal to 80% of the width of the second dummy electrode finger; or, in the width direction of the first dummy electrode finger, the two sides of the first opening are spaced apart from the edge of the first dummy electrode finger, and the two sides of the second opening are spaced apart from the edge of the second dummy electrode finger, wherein the interval is greater than or equal to 10% of the width of the dummy electrode finger.

14. An electronic module, characterized in that, Includes the surface acoustic wave device as described in any one of claims 1 to 13.

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