Surface acoustic wave device and radio frequency front-end module

Abstract

The application discloses a surface acoustic wave device and a radio frequency front-end module, and relates to the technical field of radio frequency filtering. The surface acoustic wave device comprises a piezoelectric substrate, at least one first interdigital transducer, at least one second interdigital transducer, a reflection assembly and a mass load layer; the first interdigital transducer and the second interdigital transducer are electrically connected and are arranged on the piezoelectric substrate; the reflection assembly comprises at least a first reflector; in a first direction, the first reflector is arranged between the first interdigital transducer and the second interdigital transducer, and the first direction is the arrangement direction of the first interdigital transducer and the second interdigital transducer; and the mass load layer is arranged on the side of the first reflector away from the piezoelectric substrate. The application can improve the suppression effect of a specific frequency band (for example, a frequency band close to a passband) while ensuring that the passband insertion loss is not affected.

Description

Technical Field

[0001] This application relates to the field of radio frequency filtering technology, and in particular to a surface acoustic wave device and a radio frequency front-end module. Background Technology

[0002] Surface acoustic wave (SAW) devices, such as SAW resonators, are devices that convert electrical signals into acoustic signals or vice versa. They have advantages such as small size, high stability, strong anti-interference ability, and high selectivity.

[0003] Currently, two surface acoustic wave devices are typically cascaded in a circuit to improve near-end suppression. However, this method does not significantly improve suppression in specific frequency bands (such as those close to the passband) and cannot meet the needs of practical applications. Summary of the Invention

[0004] This application provides a surface acoustic wave device and an RF front-end module that can improve the suppression effect of specific frequency bands (such as frequency bands close to the passband) while ensuring that the passband insertion loss is not affected.

[0005] In a first aspect, this application provides a surface acoustic wave device, the surface acoustic wave device comprising a piezoelectric substrate, at least one first interdigital transducer, at least one second interdigital transducer, a reflective component, and a mass load layer;

[0006] The first interdigital transducer and the second interdigital transducer are electrically connected and are both disposed on the piezoelectric substrate. The reflective component includes at least a first reflector. In a first direction, the first reflector is disposed between the first interdigital transducer and the second interdigital transducer. The first direction is the arrangement direction of the first interdigital transducer and the second interdigital transducer.

[0007] The mass load layer is disposed on the side of the first reflector away from the piezoelectric substrate.

[0008] Secondly, this application provides a surface acoustic wave device, the surface acoustic wave device comprising a piezoelectric substrate, at least one first interdigital transducer, at least one second interdigital transducer, and a reflective component;

[0009] The first interdigital transducer is electrically connected to the second interdigital transducer, and both are disposed on the piezoelectric substrate.

[0010] The reflective assembly includes a first reflector, a second reflector, and a third reflector. In a first direction, the first reflector and the second reflector are disposed on both sides of the first interdigital transducer, and the first reflector and the third reflector are disposed on both sides of the second interdigital transducer. The first direction is the arrangement direction of the first interdigital transducer and the second interdigital transducer.

[0011] The thickness of the first reflector is greater than the thickness of the second reflector and the third reflector.

[0012] Thirdly, this application provides a radio frequency front-end module, including the surface acoustic wave device as described above.

[0013] The surface acoustic wave (SAW) device provided in this application includes a piezoelectric substrate, at least one first interdigital transducer, at least one second interdigital transducer, a reflective component, and a mass loading layer. The first and second interdigital transducers are electrically connected and both are disposed on the piezoelectric substrate. The reflective component includes at least a first reflector, which is disposed between the first and second interdigital transducers in a first direction, which is the arrangement direction of the first and second interdigital transducers. The mass loading layer is disposed on the side of the first reflector away from the piezoelectric substrate. Thus, by disposing of the mass loading layer on the first reflector, the thickness of the first reflector is effectively increased, creating a low-velocity abrupt change region in that area, thereby generating a null point in a specific frequency band. This improves the suppression effect in a specific frequency band (e.g., a band close to the passband) while ensuring that the passband insertion loss is not affected and the area of ​​the SAW device remains essentially unchanged. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram comparing the passband insertion loss variation curves of a single DMS type filter and a cascaded DMS type filter provided by existing technology.

[0016] Figure 2 This is a schematic diagram of the structure of a surface acoustic wave device provided in an embodiment of this application;

[0017] Figure 3 This is a top view of a first reflector provided in an embodiment of this application;

[0018] Figure 4 yes Figure 3A schematic diagram of the cross-sectional structure along the aa direction;

[0019] Figure 5 yes Figure 3 A schematic diagram of the cross-sectional structure along the bb direction;

[0020] Figure 6(a) is a top view of another first reflector provided in an embodiment of this application;

[0021] Figure 6(b) is a schematic cross-sectional view of the structure along the cc direction in 6(a);

[0022] Figure 7(a) is a top view of another first reflector provided in an embodiment of this application;

[0023] Figure 7(b) is a schematic cross-sectional view of the structure along the dd direction in 7(a);

[0024] Figure 8(a) is a top view of another first reflector provided in an embodiment of this application;

[0025] Figure 8(b) is a schematic cross-sectional view of the structure along the ee direction in 8(a);

[0026] Figure 9 This is a cross-sectional view of another first reflector provided in an embodiment of this application;

[0027] Figure 10 This is a schematic diagram of another surface acoustic wave device provided in the embodiments of this application;

[0028] Figure 11 This is a schematic diagram of another surface acoustic wave device provided in the embodiments of this application;

[0029] Figure 12 This is a schematic diagram comparing the passband insertion loss variation curves of the surface acoustic wave device provided in this application embodiment with those of the surface acoustic wave device provided in the prior art;

[0030] Figure 13 This is a schematic diagram comparing the harmonic admittance curves of the surface acoustic wave device provided in this application embodiment with those of the surface acoustic wave device provided in the prior art;

[0031] Figure 14 This is a schematic diagram comparing the passband insertion loss variation curves of the duplexer provided in this application embodiment with those of the duplexer provided in the prior art;

[0032] Figure 15 This is an enlarged comparison of the passband insertion loss variation curves of the duplexer provided in this application embodiment and the duplexer provided in the prior art. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0035] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0036] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0037] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0038] The following is a brief description of the implementation methods in the relevant technologies.

[0039] In related technologies, some surface acoustic wave (SAW) devices exhibit good far-end suppression but poor near-end suppression due to their frequency response characteristics. Therefore, cascading two SAW devices in a circuit is often used to improve near-end suppression. However, this approach leads to problems such as increased size and deteriorated passband loss.

[0040] Taking a DMS type filter as an example, such as Figure 1 As shown, Figure 1 A schematic diagram comparing the passband insertion loss variation curves of a single DMS filter and a cascaded DMS filter is shown. Figure 1 It can be seen that cascaded DMS filters can achieve relatively better near-end suppression compared to single DMS filters, but the suppression performance is still poor for specific frequency bands (such as those close to the passband), which is difficult to meet application requirements. Specific frequency bands include those near B28A: 733MHz-748MHz.

[0041] To address this, this application provides a surface acoustic wave (SAW) device and an RF front-end module. The SAW device includes a piezoelectric substrate, at least one first interdigital transducer, at least one second interdigital transducer, a reflective component, and a mass loading layer. The first and second interdigital transducers are electrically connected and both are disposed on the piezoelectric substrate. The reflective component includes at least a first reflector, which is disposed between the first and second interdigital transducers in a first direction, which is the arrangement direction of the first and second interdigital transducers. The mass loading layer is disposed on the side of the first reflector away from the piezoelectric substrate. By providing a mass loading layer on the first reflector, the thickness of the first reflector is effectively increased, creating a low-velocity abrupt change region in that area. This generates nulls in a specific frequency band, thereby improving the suppression effect in a specific frequency band (e.g., a band close to the passband) while ensuring that the passband insertion loss is not affected and the area of ​​the SAW device remains essentially unchanged.

[0042] Please see Figure 2 , Figure 3 and Figure 4 , Figure 2 This is a schematic diagram of the structure of a surface acoustic wave device provided in an embodiment of this application. Figure 3 This is a schematic diagram of the structure of a first reflector provided in an embodiment of this application. Figure 4 yes Figure 3 A schematic diagram of the cross-sectional structure along the aa direction.

[0043] like Figure 2 , Figure 3 and Figure 4 As shown, the surface acoustic wave device 100 includes a piezoelectric substrate 10, at least one first interdigital transducer 20, at least one second interdigital transducer 30, a reflective component 40, and a mass load layer 50. The first interdigital transducer 20 and the second interdigital transducer 30 are electrically connected and are both disposed on the piezoelectric substrate 10. The reflective component 40 includes at least a first reflector 41, which is disposed on the piezoelectric substrate 10. In a first direction, the first reflector 41 is disposed between the first interdigital transducer 20 and the second interdigital transducer 30. The mass load layer 50 is disposed on the side of the first reflector 41 away from the piezoelectric substrate 10, that is, the mass load layer 50 is disposed on the first reflector 41.

[0044] The first direction refers to the arrangement direction of the first interdigital transducer 20 and the second interdigital transducer 30. The piezoelectric substrate 10 may include at least one of lithium niobate (LiNbO3) and lithium tantalate (LiTaO3), without specific limitations.

[0045] Specifically, the first reflector 41 is disposed between the first interdigital transducer 20 and the second interdigital transducer 30. The first reflector 41 can serve as a reflective grating for both the first interdigital transducer 20 and the second interdigital transducer 30, or it can serve as a reflective grating for either the first interdigital transducer 20 or the second interdigital transducer 30.

[0046] For example, the first interdigital transducer 20 and the second interdigital transducer 30 can be connected in series or in parallel, without specific limitations.

[0047] For example, the spacing between the first reflector 41 and the first interdigital transducer 20 and the second interdigital transducer 30 can be the same or different, depending on the actual design requirements. Preferably, in order to ensure the electrical connection effect between the first interdigital transducer 20 and the second interdigital transducer 30, the spacing between the first reflector 41 and the first interdigital transducer 20 and the second interdigital transducer 30 is the same.

[0048] The following describes the surface acoustic wave device 100 provided in this application embodiment, taking the parallel connection of the first interdigital transducer 20 and the second interdigital transducer 30 as an example.

[0049] like Figure 2 As shown, the surface acoustic wave device 100 provided in this application embodiment includes a first interdigital transducer 20 and a second interdigital transducer 30 connected in parallel. It can be understood that the number of the first interdigital transducers 20 and the second interdigital transducers 30 can be 3, 5, etc., and the number can be determined according to actual needs. This application embodiment describes an example of a first interdigital transducer 20 and a second interdigital transducer 30 connected in parallel. In a specific embodiment, as... Figure 2 As shown, the first interdigital transducer 20 and the second interdigital transducer 30 are connected in parallel between the input terminal 70 and the output terminal 80.

[0050] It should be noted that the embodiments in this application are described with the case that the number of the first interdigital transducers 20 and the second interdigital transducers 30 is the same. The case where the number of the first interdigital transducers 20 and the second interdigital transducers 30 is different should also be understood as being within the protection scope of this invention.

[0051] The surface acoustic wave device 100 provided in this application provides a mass load layer 50 on a first reflector 41 located between a first interdigital transducer 20 and a second interdigital transducer 30. The mass load layer 50 can effectively increase the thickness of the first reflector 41, so that the area corresponding to the first reflector 41 forms a low sound velocity change region, thereby generating a null in a specific frequency band. This improves the suppression effect of a specific frequency band (such as a frequency band close to the passband) while ensuring that the passband insertion loss is not affected and the area of ​​the surface acoustic wave device 100 remains basically unchanged.

[0052] like Figure 3 and Figure 4 As shown, in some embodiments, the surface acoustic wave device 100 further includes a dielectric layer 60, which at least covers the first reflector 41; wherein, a mass load layer 50 is disposed on the dielectric layer 60.

[0053] It should be noted that, in this embodiment, since the dielectric layer 60 covers the first reflector 41, in order to better reflect the placement position of the mass load layer 50 relative to the first reflector 41, Figure 3 The corresponding top view does not show medium layer 60, but... Figure 4 The corresponding sectional view then displays the medium layer 60, and the same operation is performed in the top view of subsequent embodiments.

[0054] For example, the dielectric layer 60 at least covers the first reflector 41 to protect it. For instance, the dielectric layer 60 can be a temperature compensation layer or a passivation layer. The mass load layer 50 is disposed on the dielectric layer 60 to effectively increase the thickness of the first reflector 41, so that the area corresponding to the first reflector 41 forms a low sound velocity abrupt change region. This improves the suppression effect of a specific frequency band (such as a frequency band close to the passband) while ensuring that the passband insertion loss is not affected.

[0055] For example, if the dielectric layer 60 is a temperature compensation layer, the temperature compensation layer covers the first reflector 41, that is, the piezoelectric substrate 10, the first reflector 41, and the temperature compensation layer are stacked in sequence. The temperature compensation layer plays a role in temperature compensation, thereby improving the negative frequency temperature characteristics of the first reflector 41. The material of the temperature compensation layer can be silicon oxide, tantalum oxide, silicon oxynitride, or other materials with a positive frequency temperature coefficient.

[0056] For example, if the dielectric layer 60 is a passivation layer, the passivation layer covers the first reflector 41, that is, the piezoelectric substrate 10, the first reflector 41, and the passivation layer are stacked in sequence. The passivation layer is mainly used to protect the first reflector 41 from corrosion. It forms a dense oxide film on the metal surface, which prevents the metal from direct contact with corrosive substances such as oxygen and moisture in the air, thereby significantly improving the corrosion resistance of the metal. The material of the passivation layer can be chromium oxide, zinc oxide, or other materials with strong corrosion resistance.

[0057] For example, the surface acoustic wave device 100 may also include multiple dielectric layers 60, each covering the first reflector 41 and stacked together. For instance, the multiple dielectric layers 60 may include a temperature compensation layer and a passivation layer, with the passivation layer disposed on the temperature compensation layer. That is, the piezoelectric substrate 10, the first reflector 41, the temperature compensation layer, and the passivation layer are stacked sequentially.

[0058] like Figure 5 As shown, in some embodiments, the width of the mass load layer 50 in the first direction is d1, and the width of the first reflector 41 in the first direction is d2, where d1 ≤ d2. Therefore, by controlling the width of the mass load layer 50 in the first direction, the suppression effect in a specific frequency band can be further improved while ensuring that the passband insertion loss is not affected.

[0059] For example, as long as the width of the mass load layer 50 in the first direction does not exceed the width of the first reflector 41 in the first direction, that is, d1≤d2. If the width d2 of the first reflector 41 in the first direction is 100nm, then the width d1 of the mass load layer 50 in the first direction can be 20nm, 50nm, 100nm, etc.

[0060] In some embodiments, Therefore, by controlling the width of the mass load layer 50 in the first direction, the suppression effect of a specific frequency band can be maintained at a high level while ensuring that the passband insertion loss is not affected.

[0061] For example, if the width d2 of the first reflector 41 in the first direction is 100nm, then the width d1 of the mass load layer 50 in the first direction can be in the range of 25nm-75nm.

[0062] Optionally, the mass load layer 50 can be positioned at any location on the first reflector 41. In some embodiments, the mass load layer 50 can be symmetrically arranged with respect to the horizontal bisector of the first reflector 41, which is perpendicular to a first direction; or, the mass load layer 50 can also be symmetrically arranged with respect to the vertical bisector of the first reflector 41, which is perpendicular to a second direction; for example, the mass load layer 50 can also be symmetrically arranged with respect to both the horizontal and vertical bisectors of the first reflector 41, thereby positioning the mass load layer 50 in the middle region of the first reflector 41, which can further improve the suppression effect of a specific frequency band while ensuring that the passband insertion loss is not affected.

[0063] For example, the surface acoustic wave device 100 may further include a plurality of mass load layers 50, all of which are disposed on the first reflector 41. For instance, the plurality of mass load layers 50 may be disposed in the middle region of the first reflector 41, and the plurality of mass load layers 50 may also be symmetrically disposed with respect to the horizontal bisector and / or vertical bisector of the first reflector 41, without specific limitations herein.

[0064] like Figure 4As shown, in some embodiments, the first reflector 41 includes a plurality of spaced-apart reflective electrode fingers 412; the mass load layer 50 has a length L1 in the second direction, and the first reflector 41 has a length L2 in the second direction, the second direction being the extending direction of the reflective electrode fingers 412, and the first direction being perpendicular to the second direction; wherein, Therefore, by controlling the length of the mass load layer 50 in the second direction, the suppression effect of a specific frequency band can be further improved while ensuring that the passband insertion loss is not affected.

[0065] For example, if the length L2 of the first reflector 41 in the second direction is 200 nm, then the length L1 of the mass load layer 50 in the second direction can range from 50 nm to 200 nm.

[0066] In some embodiments, Therefore, by controlling the length of the mass load layer 50 in the second direction, it is possible to maintain a high level of suppression effect in a specific frequency band while ensuring that the passband insertion loss is not affected.

[0067] For example, if the length L2 of the first reflector 41 in the second direction is 200 nm, then the length L1 of the mass load layer 50 in the second direction can be in the range of 150 nm to 200 nm.

[0068] In some embodiments, the projection range of the mass load layer 50 on the piezoelectric substrate 10 is less than or equal to the projection range of the first reflector 41 on the piezoelectric substrate 10. This prevents the mass load layer 50 from extending beyond the first reflector 41, thereby improving the structural stability of the surface acoustic wave device 100.

[0069] For example, the mass load layer 50 can be controlled to be disposed on the first reflector 41, and the projection of the mass load layer 50 on the piezoelectric substrate 10 can be completely within the projection range of the first reflector 41 on the piezoelectric substrate 10, so that the mass load layer 50 will not extend beyond the projection range of the first reflector 41, thereby improving the structural stability of the surface acoustic wave device 100.

[0070] Optionally, the thickness of the mass load layer 50 can be the same or different in different regions. For example, the thickness of the mass load layer 50 in different regions can be differentiated according to actual design requirements. If the actual design requires the thickness of the mass load layer 50 in region A to be greater than the thickness of the mass load layer 50 in region B, then the thickness of the mass load layer 50 in regions A and B can be set accordingly. For example, the thickness of the mass load layer 50 is the same in all regions, thereby improving the structural stability of the surface acoustic wave device 100.

[0071] In some embodiments, the first reflector 41 includes two reflective busbars 411 disposed opposite to each other. In one embodiment, the dielectric layer 60 has at least one through-hole in the thickness direction, and a portion of the mass load layer 50 passes through the through-hole and connects to at least one reflective busbar 411; in another embodiment, the mass load layer 50 and the reflective busbar 411 are spaced apart and insulated from each other in the thickness direction, i.e., the dielectric layer 60 does not have a through-hole, and the mass load layer 50 and the reflective busbar 411 are spaced apart from each other in the thickness direction.

[0072] The thickness direction is perpendicular to both the first and second directions, meaning the thickness direction is the projection direction of the mass load layer 50 onto the piezoelectric substrate 10.

[0073] As shown in Figures 6(a) and 6(b), exemplarily, the dielectric layer 60 has no through-holes in the thickness direction. In this case, the mass load layer 50 and one of the reflective busbars 411 are spaced apart in the thickness direction, that is, the dielectric layer 60 is disposed between the mass load layer 50 and the first reflector 41. Exemplarily, the projection of the mass load layer 50 in the thickness direction completely covers one of the reflective busbars 411, but does not cover the other reflective busbar 411. Exemplarily, the width of the mass load layer 50 in the first direction is the same as the width of the first reflector 41 in the first direction.

[0074] As shown in Figures 7(a) and 7(b), exemplarily, the dielectric layer 60 has a through-hole extending through the dielectric layer 60 in the thickness direction. The mass load layer 50 passes through the through-hole and is connected to one of the reflective busbars 411. In this case, the mass load layer 50 is connected to one of the reflective busbars 411 and spaced apart from the other reflective busbar 411. Exemplarily, the mass load layer 50 partially covers one of the reflective busbars 411 but does not cover the other reflective busbar 411. Exemplarily, the length of the mass load layer 50 in the second direction is the same as the sum of the lengths of the reflective busbars 411 and the reflective electrode fingers 412 in the second direction.

[0075] As shown in Figures 8(a) and 8(b), exemplarily, the dielectric layer 60 has two through holes penetrating the dielectric layer 60 in the thickness direction. The mass load layer 50 passes through the through holes and is connected to the two reflective busbars 411 respectively. In this case, the mass load layer 50 is connected to both reflective busbars 411 through the through holes. Exemplarily, the length of the mass load layer 50 in the second direction is the same as the length of the first reflector 41 in the second direction.

[0076] Optionally, the through-hole can be any through-hole that can penetrate the dielectric layer 60, such as a round hole or a square hole, without specific limitations. For example, one or more round holes can be provided on each reflective busbar 411, one or more square holes can be provided on each reflective busbar 411, and an elongated through-hole can be provided on each reflective busbar 411, with the extension direction of the through-hole being the same as the extension direction of the reflective busbar 411. As one embodiment, the through-holes on two reflective busbars 411 are correspondingly provided; for example, the positions and numbers of the through-holes on the two reflective busbars 411 are correspondingly provided.

[0077] It should be noted that the number of through holes can be determined according to the actual situation, and no specific limit is made here.

[0078] Optionally, the projection of the mass load layer 50 may completely or partially cover one of the reflective busbars 411, but not the other reflective busbar 411; or, the projection of the mass load layer 50 may partially cover both reflective busbars 411; or, the projection of the mass load layer 50 may not cover either reflective busbar 411. This application does not limit this.

[0079] like Figure 9 As shown, in some embodiments, the first reflector 41 includes a plurality of spaced-apart reflective electrode fingers 412; wherein, the mass load layer 50 is disposed on the reflective electrode fingers 412 and connected to the reflective electrode fingers 412.

[0080] Specifically, multiple reflective electrode fingers 412 are spaced apart, and each reflective electrode finger 412 is connected to two reflective busbars 411. The mass load layer 50 can be correspondingly disposed on the reflective electrode fingers 412 and connected to them. Directly disposing the mass load layer 50 on the reflective electrode fingers 412 can also increase the thickness of the first reflector 41, so that the area corresponding to the first reflector 41 forms a low sound velocity abrupt change region, thereby improving the suppression effect of specific frequency bands (such as frequency bands close to the passband) while ensuring that the passband insertion loss is not affected.

[0081] For example, the mass load layer 50 may be disposed on one or more reflective electrode fingers 412, without specific limitation.

[0082] It should be noted that in this embodiment, there is no dielectric layer 60 between the mass load layer 50 and the reflective electrode finger 412. The mass load layer 50 is disposed on the reflective electrode finger 412 and directly connected to the reflective electrode finger 412.

[0083] like Figure 9As shown, in some embodiments, the surface acoustic wave device 100 further includes a dielectric layer 60, which at least covers the reflective electrode finger 412; wherein the dielectric layer 60 includes a temperature compensation layer.

[0084] For example, the dielectric layer 60 covers at least all the reflective electrode fingers 412 in the first reflector 41 to protect the reflective electrode fingers 412. For example, the dielectric layer 60 can be a temperature compensation layer or a passivation layer. The mass load layer 50 is disposed on the reflective electrode fingers 412 to effectively increase the thickness of the first reflector 41, so that the area corresponding to the reflective electrode fingers 412 on which the mass load layer 50 is disposed forms a low sound velocity abrupt change region, thereby improving the suppression effect of a specific frequency band (such as a frequency band close to the passband) while ensuring that the passband insertion loss is not affected.

[0085] For example, the dielectric layer 60 is a temperature compensation layer. This temperature compensation layer may only cover the reflective electrode finger 412, or it may cover both the reflective electrode finger 412 and the mass load layer 50; no specific limitation is made here. The temperature compensation layer serves to compensate for temperature fluctuations, thereby improving the negative frequency temperature characteristics of the first reflector 41. The material of the temperature compensation layer can be silicon oxide, tantalum oxide, silicon oxynitride, or other materials with a positive frequency temperature coefficient.

[0086] like Figure 9 As shown, preferably, since the mass load layer 50 is generally thicker, while the temperature compensation layer is generally not made too thick, that is, the thickness of the temperature compensation layer is generally less than the thickness of the mass load layer 50. Therefore, in this embodiment of the application, the temperature compensation layer only covers all the reflective electrode fingers 412 in the first reflector 41, and does not completely cover the mass load layer 50 disposed on the reflective electrode fingers 412, thereby avoiding increasing the overall thickness of the surface acoustic wave device 100, making the volume of the surface acoustic wave device 100 larger, which is not conducive to subsequent applications.

[0087] like Figure 9 As shown, in some embodiments, the mass load layer 50 includes a plurality of spaced metal blocks, each metal block corresponding to at least one reflective electrode finger 412 and disposed on the corresponding reflective electrode finger 412.

[0088] Specifically, multiple metal blocks are respectively set on the corresponding reflective electrode fingers 412, and the metal blocks are spaced apart. If two metal blocks are connected, it may cause a short circuit between their corresponding reflective electrode fingers 412.

[0089] For example, the metal block can be made of metals such as aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, and tungsten. No specific limitation is made here; the material can be selected based on the specific circumstances. However, the selected material needs to have good electrical conductivity. Preferably, the material of the metal block is the same as the material of the reflective electrode finger 412, thereby giving the metal block and the reflective electrode finger 412 a better bonding force.

[0090] In some embodiments, the coverage area of ​​the metal block is less than or equal to the coverage area of ​​its corresponding reflective electrode finger 412.

[0091] For example, the coverage area of ​​the metal block can be controlled to be less than or equal to the coverage area of ​​its corresponding reflective electrode finger 412. By controlling the coverage area of ​​the metal block, the pressure on its corresponding reflective electrode finger 412 can be reduced, thereby improving the structural stability of the surface acoustic wave device 100. At the same time, it can also prevent adjacent metal blocks from connecting and causing a short circuit between their corresponding reflective electrode fingers 412.

[0092] It should be noted that the projected shape of the metal block can be any shape, such as a rectangle, square, or circle, and the number of metal blocks can also be any number, without any specific limitation. For example, if the coverage area of ​​the metal block is large, only one metal block can be set on the reflective electrode finger 412; if the coverage area of ​​the metal block is small, multiple metal blocks can be set on the reflective electrode finger 412.

[0093] In some embodiments, the width of the metal block in the first direction is less than or equal to the width of its corresponding reflective electrode finger 412 in the first direction, and / or the length of the metal block in the second direction is less than or equal to the length of its corresponding reflective electrode finger 412 in the second direction, wherein the second direction is the extension direction of the reflective electrode finger 412, and the first direction intersects the second direction.

[0094] Preferably, the first direction is perpendicular to the second direction.

[0095] For example, the width of the metal block in the first direction is controlled to be less than or equal to the width of its corresponding reflective electrode finger 412 in the first direction, or the length of the metal block in the second direction is controlled to be less than or equal to the length of its corresponding reflective electrode finger 412 in the second direction.

[0096] By controlling the width of the metal block in the first direction to be less than or equal to the width of its corresponding reflective electrode finger 412 in the first direction, and simultaneously controlling the length of the metal block in the second direction to be less than or equal to the length of its corresponding reflective electrode finger 412 in the second direction, the projection range of the metal block on the piezoelectric substrate 10 is made less than or equal to the projection range of its corresponding reflective electrode finger 412 on the piezoelectric substrate 10. This effectively reduces the pressure borne by the corresponding reflective electrode finger 412 and improves the structural stability of the surface acoustic wave device 100.

[0097] For example, if the number of metal blocks is less than the number of reflective electrode fingers 412, the metal blocks can be placed on any different or the same reflective electrode fingers 412. If the metal blocks are placed on any different reflective electrode fingers 412, for example, the distance between any two adjacent metal blocks in the first direction can be controlled to be the same, that is, any two adjacent metal blocks are spaced apart by the same number of reflective electrode fingers 412, thereby avoiding the concentration of metal blocks in the central area of ​​the first reflector 41. It is also possible to control the placement positions of any two adjacent metal blocks on the reflective electrode fingers 412 to be different, for example, one metal block can be placed near one of the reflective busbars on the reflective electrode finger 412, and the other metal block can be placed near another reflective busbar on the reflective electrode finger 412.

[0098] like Figure 2 As shown, in some embodiments, the reflective assembly 40 further includes a second reflector 42 and a third reflector 43; in a first direction, the first reflector 41 and the second reflector 42 are disposed on both sides of the first interdigital transducer 20, and the first reflector 41 and the third reflector 43 are disposed on both sides of the second interdigital transducer 30.

[0099] Specifically, the first reflector 41 is disposed between the first interdigital transducer 20 and the second interdigital transducer 30, and the first reflector 41 and the second reflector 42 are disposed on both sides of the first interdigital transducer 20, and the first reflector 41 and the third reflector 43 are disposed on both sides of the second interdigital transducer 30. Therefore, the space between the second reflector 42 and the third reflector 43 includes at least the first interdigital transducer 20, the first reflector 41 and the second interdigital transducer 30.

[0100] For example, the structural parameters of the second reflector 42 and the third reflector 43 may be the same or different. The structural parameters of the second reflector 42 and the third reflector 43 may include one or more of the following: the distance between the center lines of two adjacent reflective electrode fingers 412, the number of reflective electrode fingers 412, the width of the reflective electrode fingers 412 in the first direction, and the length of the reflective electrode fingers 412 in the second direction, without being specifically limited here.

[0101] In some embodiments, the first reflector 41, the second reflector 42, and the first interdigital transducer 20 constitute a first resonator, and the first reflector 41, the third reflector 43, and the second interdigital transducer 30 constitute a second resonator; wherein, both the first resonator and the second resonator can be surface acoustic wave resonators.

[0102] In one implementation, at least one of the first resonator and the second resonator is a longitudinally coupled dual-mode surface acoustic wave resonator.

[0103] For example, if the first resonator is a longitudinally coupled dual-mode surface acoustic wave (SAW) resonator, then the second resonator can be any SAW resonator; if the second resonator is a longitudinally coupled dual-mode SAW resonator, then the first resonator can be any SAW resonator.

[0104] like Figure 10 As shown, for example, both the first resonator and the second resonator can be longitudinally coupled dual-mode surface acoustic wave resonators.

[0105] Longitudinal coupled dual-mode surface acoustic wave resonators exhibit good far-end suppression but poor near-end suppression in their frequency response characteristics. For example... Figure 1 As shown, when at least one of the first and second resonators is a longitudinally coupled dual-mode surface acoustic wave resonator, although relatively good near-end suppression can be obtained, the suppression for specific frequency bands (such as those close to the passband) is still poor, which is difficult to meet the application requirements, and will also have a certain impact on the passband insertion loss.

[0106] As for the surface acoustic wave device 100 provided in this application, even if at least one of the first resonator and the second resonator is a longitudinally coupled dual-mode surface acoustic wave resonator, it is possible to improve the suppression effect of a specific frequency band (such as the frequency band close to the passband) while ensuring that the passband insertion loss is not affected and the area of ​​the surface acoustic wave device 100 remains basically unchanged.

[0107] It is understood that the surface acoustic wave resonator can be a general surface acoustic wave resonator, a temperature-compensated surface acoustic wave resonator, a surface acoustic wave resonator with a piezoelectric substrate 10 including a multilayer thin film structure, a resonator structure with a cavity or groove on the piezoelectric substrate 10, or a longitudinally coupled resonator, a two-mode or multi-mode surface acoustic wave filter, or a trapezoidal filter or duplexer containing the above-mentioned surface acoustic wave resonators, etc., and this application does not make specific limitations.

[0108] like Figure 11As shown, in some embodiments, the reflective assembly 40 further includes a fourth reflector 44, with the first reflector 41 and the fourth reflector 44 disposed adjacent to each other, and both the first reflector 41 and the fourth reflector 44 disposed between the first interdigital transducer 20 and the second interdigital transducer 30; in a first direction, the first reflector 41 and the second reflector 42 are disposed on both sides of the first interdigital transducer 20, and the third reflector 43 and the fourth reflector 44 are disposed on both sides of the second interdigital transducer 30; wherein, the mass load layer 50 is disposed on at least one of the first reflector 41 and the fourth reflector 44.

[0109] Since both the first reflector 41 and the fourth reflector 44 are disposed between the first interdigital transducer 20 and the second interdigital transducer 30, in this embodiment of the application, the first reflector 41, the second reflector 42 and the first interdigital transducer 20 constitute the first resonator, and the third reflector 43, the fourth reflector 44 and the second interdigital transducer 30 constitute the second resonator; wherein, at least one of the first resonator and the second resonator is a longitudinally coupled dual-mode surface acoustic wave resonator.

[0110] For example, the mass load layer 50 may be disposed on only the first reflector 41 or the fourth reflector 44. Preferably, the mass load layer 50 is disposed on both the first reflector 41 and the fourth reflector 44.

[0111] In some embodiments, see details. Figure 4 In the first reflector 41, there are multiple reflective electrode fingers 412 spaced apart. The mass load layer 50 has a thickness of h1, and the reflective electrode fingers 412 have a thickness of h2; wherein h1 ≥ 5h2. Therefore, by controlling the thickness of the mass load layer 50, the suppression effect in a specific frequency band can be further improved while ensuring that the passband insertion loss is not affected.

[0112] For example, if the thickness h2 of the reflective electrode finger 412 is 20 nm, then the thickness of the mass load layer 50 is at least greater than or equal to 100 nm.

[0113] In some embodiments, the first interdigital transducer 20 and the second interdigital transducer 30 each include two comb-shaped electrodes disposed opposite to each other. Each comb-shaped electrode includes a first busbar and a plurality of first electrode fingers connected to and spaced apart from the first busbar. The first electrode fingers of the two comb-shaped electrodes are arranged alternately. In a second direction, there is an overlapping region and a gap region located at both ends of the overlapping region between the two first busbars. The overlapping region is the region where the projections of each first electrode finger along the first direction overlap. The length of the overlapping region of the first interdigital transducer 20 in the second direction is the same as the length of the overlapping region of the second interdigital transducer 30 in the second direction. The second direction is the extension direction of the first electrode fingers, and the first direction intersects the second direction.

[0114] Preferably, the first direction is perpendicular to the second direction.

[0115] The region between the first busbar and the overlapping region has two gap regions, which are located at both ends of the overlapping region. The length of the overlapping region in the second direction is the aperture length of the IDT.

[0116] For example, generally speaking, the structural parameters of the first interdigital transducer 20 and the second interdigital transducer 30 may be the same or different. The structural parameters of the first interdigital transducer 20 and the second interdigital transducer 30 may include one or more of the following: the distance between the center lines of two adjacent first electrode fingers, the number of first electrode fingers, the length of the gap region in the second direction, the width of the first electrode fingers in the first direction, and the length of the first electrode fingers in the second direction, which are not specifically limited here.

[0117] Preferably, the aperture length of the first interdigital transducer 20 can be controlled to be the same as that of the second interdigital transducer 30, while the other structural parameters of the first interdigital transducer 20 and the second interdigital transducer 30 can be controlled to be different, such as the distance between the center lines of two adjacent first electrode fingers and the number of first electrode fingers. Therefore, by controlling the structural parameters of the first interdigital transducer 20 and the second interdigital transducer 30, other performance indicators of the interdigital transducer, such as operating frequency, operating bandwidth, and surface acoustic wave intensity, can be improved.

[0118] The following will provide a detailed description of another surface acoustic wave device 100 provided in the embodiments of this application.

[0119] like Figure 2 , Figure 3 and Figure 4 As shown, the surface acoustic wave device 100 includes a piezoelectric substrate 10, at least one first interdigital transducer 20, at least one second interdigital transducer 30, and a reflective assembly 40. The first interdigital transducer 20 and the second interdigital transducer 30 are electrically connected and are both disposed on the piezoelectric substrate 10. The reflective assembly 40 includes at least one first reflector 41. In a first direction, the first reflector 41 is disposed on the piezoelectric substrate 10 and between the first interdigital transducer 20 and the second interdigital transducer 30. The first reflector 41 and the second reflector 42 are disposed on both sides of the first interdigital transducer 20, and the first reflector 41 and the third reflector 43 are disposed on both sides of the second interdigital transducer 30. The thickness of the first reflector 41 is greater than the thickness of the second reflector 42 and the third reflector 43.

[0120] Specific embodiments of the piezoelectric substrate 10, the first interdigital transducer 20, the second interdigital transducer 30, and the reflective component 40 can be found in the preceding embodiments and will not be repeated here. The structural parameters of the second reflector 42 and the third reflector 43 are generally the same, that is, the thicknesses of the second reflector 42 and the third reflector 43 are the same.

[0121] For example, the thickness of the first reflector 41 can be increased by providing a mass load layer 50 on the first reflector 41 or by thickening the reflective electrode fingers 412, so that the thickness of the first reflector 41 is greater than the thickness of the second reflector 42 and the third reflector 43.

[0122] It should be noted that specific embodiments of the mass load layer 50 and the metal block can be found in the previous embodiments, and will not be repeated here.

[0123] The surface acoustic wave device 100 provided in this application controls the thickness of the first reflector 41 to be greater than the thickness of the second reflector 42 and the third reflector 43, so that the area corresponding to the first reflector 41 forms a low sound velocity change region, thereby generating a null in a specific frequency band. This improves the suppression effect in a specific frequency band (such as a frequency band close to the passband) while ensuring that the passband insertion loss is not affected and the area of ​​the surface acoustic wave device 100 remains basically unchanged.

[0124] In some embodiments, the first reflector 41 includes a plurality of spaced-apart reflective electrode fingers 412, the thickness of the reflective electrode fingers 412 being h2, the thickness of the first reflector 41 being h3, and the thicknesses of the second reflector 42 and the third reflector 43 being h4; wherein h3-h4≥5h2. Therefore, by controlling the thickness of the first reflector 41, the thickness difference between the first reflector 41 and the second and third reflectors 42 and 43 can be controlled, thereby further improving the suppression effect in a specific frequency band while ensuring that the passband insertion loss is not affected.

[0125] For example, if the thickness h2 of the reflective electrode finger 412 is 20 nm, and the thickness h4 of the second reflector 42 and the third reflector 43 is 50 nm, then the thickness h3 of the first reflector 41 is at least greater than or equal to 150 nm.

[0126] The following will compare the passband insertion loss variation curve and harmonic admittance curve of the surface acoustic wave device (executive) provided in this application with those of the surface acoustic wave device (comparative example) provided in the related art based on the test results.

[0127] In the embodiments, the surface acoustic wave device provided has a mass load layer on the first reflector, while the surface acoustic wave device provided in the comparative examples does not have a mass load layer on the first reflector. The remaining structures are the same as those of the surface acoustic wave device provided in the embodiments, and the following embodiments and comparative examples are all configured in this way.

[0128] like Figure 12 As shown in the actual test results, it can be seen that in a specific frequency band (the frequency band close to the passband), especially in the frequency band close to the passband, namely the frequency band corresponding to 733MHz-748MHz, the out-of-band suppression effect of the surface acoustic wave device in this embodiment is significantly better than that of the surface acoustic wave device in the comparative example. That is, the surface acoustic wave device provided in this application embodiment achieves stray mode suppression in the frequency band close to the passband.

[0129] like Figure 13 As shown in the actual test results, it can be seen that in a specific frequency band (the band close to the passband), especially in the band close to the passband, namely the frequency band corresponding to 733MHz-748MHz, the out-of-band suppression effect of the surface acoustic wave device of the embodiment is significantly better than that of the surface acoustic wave device of the comparative example. At the same time, in the passband frequency band, namely the frequency band corresponding to 758MHz-788MHz, the admittance amplitude of the surface acoustic wave device of the embodiment and the surface acoustic wave device of the comparative example is not much different, which indicates that the admittance of the surface acoustic wave device provided in the embodiment of this application does not deteriorate in the passband frequency band.

[0130] The following will compare the passband insertion loss variation curves of the duplexer (executive) provided in this application with those of the duplexer (comparative example) provided in related technologies based on the test results.

[0131] The duplexer provided in the embodiment uses the surface acoustic wave device provided in this application, that is, a mass load layer is provided on the first reflector. The duplexer provided in the comparative example uses the surface acoustic wave device provided by related technology, that is, no mass load layer is provided on the first reflector. The rest of the structure is the same as the duplexer provided in the embodiment. The following embodiments and comparative examples are all configured in this way.

[0132] like Figure 14 As shown in the actual test results, it can be seen that in a specific frequency band (the frequency band close to the passband), especially in the frequency band close to the passband, namely the frequency band corresponding to 733MHz-748MHz, the out-of-band suppression effect of the duplexer in this embodiment is significantly better than that of the duplexer in the comparative example. That is, the duplexer provided in this application embodiment achieves spurious mode suppression in the frequency band close to the passband.

[0133] like Figure 15 As shown in the actual test results, it can be seen that in the passband frequency band, namely the frequency band corresponding to 758MHz-788MHz, the insertion loss of the duplexer in this embodiment is basically the same as that of the duplexer in the comparative example, which means that the insertion loss of the duplexer provided in this application embodiment is basically unaffected in the passband frequency band.

[0134] In the case where the surface acoustic wave device 100 is a filter, the filter provided in the embodiments of this application will be described in detail below.

[0135] The filter includes multiple series-arm surface acoustic wave (SAW) devices 100 connected in series between the input terminal 70 and the output terminal 80, and multiple parallel-arm SAW devices 100 connected at one end to the series-arm SAW device 100 and at the other end to the ground terminal. At least one of the series-arm SAW device 100 and the parallel-arm SAW device 100 can be the SAW device 100 provided in any of the above embodiments. This filter can improve the suppression effect of a specific frequency band (such as a frequency band close to the passband) while ensuring that the passband insertion loss is not affected.

[0136] This application also provides a radio frequency (RF) front-end module, which includes the surface acoustic wave (SAW) device 100 described in any of the above embodiments. This RF front-end module can improve the suppression effect of specific frequency bands (such as those close to the passband) while ensuring that the passband insertion loss is not affected, thereby improving the reliability, security, and practicality of the RF front-end module.

[0137] The surface acoustic wave device 100 can be integrated into a filter, duplexer, or multiplexer. The RF front-end module may also include at least one other device such as an antenna, power amplifier, low-noise amplifier, or switch, without specific limitations.

[0138] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A surface acoustic wave device, characterized in that, The surface acoustic wave device includes: piezoelectric substrate; At least one first interdigital transducer and at least one second interdigital transducer, the first interdigital transducer and the second interdigital transducer being electrically connected, and both being disposed on the piezoelectric substrate. A reflective assembly, the reflective assembly including at least a first reflector, wherein the first reflector is disposed between the first interdigital transducer and the second interdigital transducer in a first direction, and the first direction is the arrangement direction of the first interdigital transducer and the second interdigital transducer; A mass load layer is disposed on the side of the first reflector away from the piezoelectric substrate.

2. The surface acoustic wave device according to claim 1, characterized in that, The surface acoustic wave device further includes a dielectric layer, which at least covers the first reflector; The mass load layer is disposed on the dielectric layer.

3. The surface acoustic wave device according to claim 2, characterized in that, The width of the mass load layer in the first direction is d1, and the width of the first reflector in the first direction is d2. Where d1≤d2.

4. The surface acoustic wave device according to claim 3, characterized in that, 5. The surface acoustic wave device according to claim 2, characterized in that, The first reflector includes a plurality of spaced-apart reflective electrodes; The mass load layer has a length of L1 in the second direction, the first reflector has a length of L2 in the second direction, the second direction is the extension direction of the reflective electrode, and the first direction is perpendicular to the second direction. in, 6. The surface acoustic wave device according to claim 5, characterized in that, 7. The surface acoustic wave device according to claim 2, characterized in that, The projection range of the mass load layer on the piezoelectric substrate is less than or equal to the projection range of the first reflector on the piezoelectric substrate.

8. The surface acoustic wave device according to claim 2, characterized in that, The first reflector includes two reflective busbars arranged opposite to each other; Wherein, in the thickness direction of the dielectric layer, the dielectric layer is provided with at least one through hole, and a portion of the mass load layer passes through the through hole and is connected to at least one of the reflective busbars; or, the mass load layer and the reflective busbars are spaced apart and insulated from each other in the thickness direction.

9. The surface acoustic wave device according to claim 2, characterized in that, The dielectric layer includes a temperature compensation layer.

10. The surface acoustic wave device according to claim 1, characterized in that, The first reflector includes a plurality of spaced-apart reflective electrodes; The mass load layer is disposed on the reflective electrode finger and connected to the reflective electrode finger.

11. The surface acoustic wave device according to claim 10, characterized in that, The surface acoustic wave device further includes a dielectric layer, which at least covers the reflective electrode fingers; The dielectric layer includes a temperature compensation layer.

12. The surface acoustic wave device according to claim 10, characterized in that, The mass load layer includes a plurality of spaced metal blocks, each of which corresponds to at least one of the reflective electrode fingers and is disposed on the corresponding reflective electrode finger.

13. The surface acoustic wave device according to claim 12, characterized in that, The coverage area of ​​the metal block is less than or equal to the coverage area of ​​its corresponding reflective electrode finger.

14. The surface acoustic wave device according to claim 13, characterized in that, The width of the metal block in the first direction is less than or equal to the width of its corresponding reflective electrode finger in the first direction, and / or the length of the metal block in the second direction is less than or equal to the length of its corresponding reflective electrode finger in the second direction, the second direction being the extension direction of the reflective electrode finger, and the first direction intersects the second direction.

15. The surface acoustic wave device according to claim 1, characterized in that, The reflective assembly further includes a second reflector and a third reflector; In the first direction, the first reflector and the second reflector are disposed on both sides of the first interdigital transducer, and the first reflector and the third reflector are disposed on both sides of the second interdigital transducer.

16. The surface acoustic wave device according to claim 15, characterized in that, The reflective assembly further includes a fourth reflector, the first reflector and the fourth reflector are arranged adjacent to each other, and both the first reflector and the fourth reflector are arranged between the first interdigital transducer and the second interdigital transducer. In the first direction, the first reflector and the second reflector are disposed on both sides of the first interdigital transducer, and the third reflector and the fourth reflector are disposed on both sides of the second interdigital transducer; The mass load layer is disposed on at least one of the first reflector and the fourth reflector.

17. The surface acoustic wave device according to claim 15, characterized in that, The first reflector, the second reflector, and the first interdigital transducer constitute a first resonator, and the first reflector, the third reflector, and the second interdigital transducer constitute a second resonator. Wherein, at least one of the first resonator and the second resonator is a longitudinally coupled two-mode surface acoustic wave resonator.

18. The surface acoustic wave device according to any one of claims 1-17, characterized in that, The first reflector includes a plurality of spaced-apart reflective electrode fingers, the mass load layer has a thickness of h1, and the reflective electrode fingers have a thickness of h2; Where h1 ≥ 5h2.

19. The surface acoustic wave device according to any one of claims 1-17, characterized in that, Both the first interdigital transducer and the second interdigital transducer include two comb-shaped electrodes arranged opposite each other. Each comb-shaped electrode includes a first busbar and a plurality of first electrode fingers connected to and spaced apart from the first busbar. The first electrode fingers of the two comb-shaped electrodes are arranged alternately. In the second direction, there is an overlapping area and a gap area located at both ends of the overlapping area between the two first busbars. Wherein, the length of the overlapping region of the first interdigital transducer in the second direction is the same as the length of the overlapping region of the second interdigital transducer in the second direction, the second direction is the extension direction of the first electrode finger, and the first direction intersects the second direction.

20. A surface acoustic wave device, characterized in that, The surface acoustic wave device includes: piezoelectric substrate; At least one first interdigital transducer and at least one second interdigital transducer, the first interdigital transducer and the second interdigital transducer being electrically connected, and both being disposed on the piezoelectric substrate. A reflective assembly, comprising a first reflector, a second reflector, and a third reflector, wherein in a first direction, the first reflector and the second reflector are disposed on both sides of the first interdigital transducer, and the first reflector and the third reflector are disposed on both sides of the second interdigital transducer, and the first direction is the arrangement direction of the first interdigital transducer and the second interdigital transducer; The thickness of the first reflector is greater than the thickness of the second reflector and the third reflector.

21. The surface acoustic wave device according to claim 20, characterized in that, The first reflector includes a plurality of spaced-apart reflective electrode fingers, the thickness of the reflective electrode fingers is h2, the thickness of the first reflector is h3, and the thickness of the second reflector and the third reflector is h4. Where h3-h4≥5h2.

22. A radio frequency front-end module, characterized in that, Includes the surface acoustic wave device as described in any one of claims 1-21.

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