Surface acoustic wave resonator, filter and electronic apparatus

Abstract

The present application belongs to the technical field of semiconductors. Disclosed are a surface acoustic wave resonator, a filter and an electronic apparatus. The surface acoustic wave resonator comprises: a piezoelectric layer; an interdigital transducer, located on one side of the piezoelectric layer in the thickness direction; and reflection structures, wherein two opposite sides of the interdigital transducer in a second direction are respectively provided with the reflection structures, at least part of the reflection structure on at least one of the two opposite sides of the interdigital transducer in the second direction is a groove structure, and the groove structure is located in the piezoelectric layer. The thickness direction, a first direction and the second direction are perpendicular to each other. The side of the groove structure close to the interdigital transducer is provided with a first groove wall arranged corresponding to an active region and a second groove wall at least partially arranged corresponding to a passive region, the first groove wall extending in the first direction, and the second groove wall being connected to the first groove wall and being inclined in a direction facing away from the interdigital transducer. The present application can reduce the volume of the resonator, reduce interference with other resonators, and suppress spurious modes in the resonator.

Description

Surface acoustic wave resonators, filters and electronic devices Technical Field

[0001] This application belongs to the field of semiconductor technology, and in particular relates to a surface acoustic wave resonator, filter and electronic device. Background Technology

[0002] Surface acoustic wave (SAW) resonators have advantages such as low insertion loss, wide bandwidth, low cost, and mass production capability, and are widely used in mobile communication equipment. With the rapid development of mobile communication technology, the demand for smaller terminals has increased, making the miniaturization of SAW resonators used in terminals a pressing issue. However, the interdigital transducers in SAW resonators have reflective gratings on both sides, which occupy a large space, resulting in a larger resonator size and hindering miniaturization. Summary of the Invention

[0003] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a surface acoustic wave resonator, filter, and electronic device that can reduce the size of the resonator, reduce interference to other resonators, and suppress stray modes within the resonator.

[0004] In a first aspect, this application provides a surface acoustic wave resonator, comprising:

[0005] piezoelectric layer;

[0006] An interdigital transducer is located on one side of the thickness direction of the piezoelectric layer; the interdigital transducer includes an active region and passive regions located on opposite sides of the active region along a first direction;

[0007] The reflective structure has reflective structures on opposite sides of the interdigital transducer along the second direction, and at least a portion of the reflective structure on at least one side of the opposite sides of the interdigital transducer along the second direction is a groove structure, the groove structure being located in the piezoelectric layer; the thickness direction, the first direction, and the second direction are perpendicular to each other.

[0008] The groove structure has a first groove wall corresponding to the active region and a second groove wall corresponding to the passive region on the side near the interdigital transducer. The first groove wall extends along a first direction, and the second groove wall is connected to the first groove wall and tilted in a direction away from the interdigital transducer.

[0009] According to the surface acoustic wave resonator of this application, by setting at least a portion of the reflection structure on at least one side of the interdigital transducer along the second direction as a groove structure, and the groove structure is located in the piezoelectric layer, the reflection of surface acoustic waves is achieved by utilizing the abrupt change in acoustic impedance at the boundary of the groove structure. The width of the groove structure does not need to be too large, reducing the space occupied by the reflection structure, thereby reducing the volume of the resonator. The side of the groove structure near the interdigital transducer has a first groove wall corresponding to the active region. The first groove wall extends along the first direction to reflect the main mode acoustic wave generated in the active region back to the active region. The reflection effect is strong, reducing interference to other resonators. The side of the groove structure near the interdigital transducer also has at least a portion of a second groove wall corresponding to the passive region. The second groove wall is inclined in the direction away from the interdigital transducer to scatter the stray mode acoustic wave generated in the passive region to the outside of the resonator, thereby suppressing stray modes in the resonator.

[0010] According to one embodiment of this application, at least some of the reflective structures on opposite sides of the interdigital transducer along the second direction are groove structures; or,

[0011] At least a portion of the reflective structure on one of the opposite sides of the interdigital transducer along the second direction is a groove structure, and the reflective structure on the other side of the opposite sides of the interdigital transducer along the second direction is a reflective grating, with the reflective grating disposed in the same layer as the interdigital transducer; or,

[0012] The reflection structure of at least one of the opposite sides of the interdigital transducer along the second direction is a groove structure and a reflection grating arranged along the second direction.

[0013] According to one embodiment of this application, the passive region includes a first passive sub-region and a second passive sub-region located on opposite sides of the active region along a first direction, and the second trench wall includes a first sub-wall that is at least partially corresponding to the first passive sub-region and a second sub-wall that is at least partially corresponding to the second passive sub-region.

[0014] The first sub-wall and the second sub-wall are respectively connected to the opposite sides of the first groove wall along the first direction, and the first sub-wall is inclined in the direction away from the interdigital transducer, and the second sub-wall is inclined in the direction away from the interdigital transducer.

[0015] According to one embodiment of this application, the angle between the first sub-wall and the direction away from the interdigital transducer is 45° to 75°, and the angle between the second sub-wall and the direction away from the interdigital transducer is 45° to 75°.

[0016] According to one embodiment of this application, the groove structure has a third groove wall on the side opposite to the interdigital transducer, which is at least partially disposed corresponding to the active region and the passive region, and the third groove wall extends along a first direction.

[0017] According to one embodiment of this application, the groove structure includes a plurality of grooves spaced apart along a second direction;

[0018] The target groove among the multiple grooves has a first groove wall and a second groove wall on the side near the interdigital transducer. The target groove is the groove closest to the interdigital transducer among the multiple grooves.

[0019] According to one embodiment of this application, the groove walls on opposite sides of the plurality of grooves extend along the first direction, respectively.

[0020] According to one embodiment of this application, the depth of the groove structure along the thickness direction is 0.5λ to 2λ, where λ is the wavelength, the width of the groove structure along the second direction is greater than 0.25λ, and the length of the groove structure along the first direction is greater than or equal to the length of the interdigital transducer along the first direction.

[0021] According to one embodiment of this application, the surface acoustic wave resonator further includes a substrate located on the side of the piezoelectric layer away from the interdigital transducer;

[0022] The depth of the groove structure along the thickness direction is 0.25h to 1h, where h is the thickness of the piezoelectric layer. The width of the groove structure along the second direction is greater than 0.25λ, where λ is the wavelength. The length of the groove structure along the first direction is greater than or equal to the length of the interdigital transducer along the first direction.

[0023] According to one embodiment of this application, the groove wall of the groove structure is at least one of planar, serrated, and wavy, and the groove wall includes at least a first groove wall or a second groove wall.

[0024] In a second aspect, this application provides a filter including a plurality of surface acoustic wave (SAW) resonators spaced apart along a second direction, wherein the SAW resonators are SAW resonators as described in the first aspect above.

[0025] At least some of the reflection structures between the interdigital transducers of at least some of the adjacent surface acoustic wave resonators are groove structures.

[0026] According to one embodiment of this application, the interdigital transducers of adjacent surface acoustic wave resonators include a first interdigital transducer and a second interdigital transducer.

[0027] The groove structure has a first groove wall corresponding to the active region of the first interdigital transducer and a second groove wall corresponding to at least part of the passive region of the first interdigital transducer on the side near the first interdigital transducer; the groove structure also has a first groove wall corresponding to the active region of the second interdigital transducer and a second groove wall corresponding to at least part of the passive region of the second interdigital transducer on the side near the second interdigital transducer.

[0028] According to one embodiment of this application, the active region of the first interdigital transducer and the active region of the second interdigital transducer have different lengths along the first direction.

[0029] According to one embodiment of this application, the length of the first groove wall on the side of the groove structure near the first interdigital transducer is different from that of the first groove wall on the side of the groove structure near the second interdigital transducer along the first direction.

[0030] Thirdly, this application provides an electronic device including the filter as described in the second aspect above.

[0031] The above-described one or more technical solutions in the embodiments of this application have at least one of the following technical effects:

[0032] By setting at least a portion of the reflection structure on at least one side of the interdigital transducer along the second direction as a groove structure, and the groove structure being located in the piezoelectric layer, the reflection of surface acoustic waves is achieved by utilizing the abrupt change in acoustic impedance at the boundary of the groove structure. The width of the groove structure does not need to be too large, reducing the space occupied by the reflection structure and thus reducing the volume of the resonator. The side of the groove structure near the interdigital transducer has a first groove wall corresponding to the active region, which extends along the first direction to reflect the main mode acoustic waves generated in the active region back to the active region. The reflection effect is strong, reducing interference to other resonators. The side of the groove structure near the interdigital transducer also has at least a portion of a second groove wall corresponding to the passive region, which is inclined in the direction away from the interdigital transducer to scatter the stray mode acoustic waves generated in the passive region to the outside of the resonator, thereby suppressing stray modes in the resonator.

[0033] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0034] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0035] Figure 1 is one of the structural schematic diagrams of the surface acoustic wave resonator provided in the embodiments of this application.

[0036] Figure 2 is a second schematic diagram of the structure of the surface acoustic wave resonator provided in the embodiment of this application.

[0037] Figure 3 is one of the top views of the surface acoustic wave resonator provided in the embodiments of this application.

[0038] Figure 4 is a top view of the surface acoustic wave resonator provided in the embodiment of this application.

[0039] Figure 5 is a graph showing the total reflectivity of the reflective grating of a surface acoustic wave resonator in the related technology when the number of reflective strips is different.

[0040] Figure 6 is a comparison of the total reflectivity of the reflection structure in the surface acoustic wave resonator provided by the related technology and the embodiment of this application.

[0041] Figure 7 is a top view of the surface acoustic wave resonator provided in the embodiment of this application.

[0042] Figure 8 is one of the simulated S21 response curves of the surface acoustic wave resonator provided in the embodiments of this application.

[0043] Figure 9 is a simulation S21 response curve of the groove structure of the surface acoustic wave resonator provided in the embodiment of this application at different depths.

[0044] Figure 10 is the second simulation S21 response curve of the surface acoustic wave resonator provided in the embodiment of this application.

[0045] Figure 11 is a schematic diagram of the filter structure provided in an embodiment of this application.

[0046] Figure 12 is a top view of the filter provided in an embodiment of this application. Detailed Implementation

[0047] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0048] The surface acoustic wave resonator, filter, and electronic device provided in the embodiments of this application are described below with reference to the accompanying drawings.

[0049] Figures 1 and 2 are schematic diagrams of the surface acoustic wave (SAW) resonator provided in the embodiments of this application. The SAW resonator may include a NORMAL-SAW resonator, a POI-SAW resonator, or a TC-SAW resonator, and may also include other types of SAW resonators, which are not specifically limited here.

[0050] As shown in Figures 1 and 2, the surface acoustic wave resonator includes a piezoelectric layer 2, an interdigital transducer 3, and a reflection structure.

[0051] The interdigital transducer (IDT) 3 is located on one side of the thickness direction Z of the piezoelectric layer 2. The piezoelectric layer 2 may include piezoelectric materials such as lithium tantalate, lithium niobate, aluminum nitride, or piezoelectric ceramics.

[0052] Referring to Figures 3 and 4, the interdigital transducer 3 includes an active region 10 and passive regions located on opposite sides of the active region 10 along the first direction X. For example, the passive regions may include a first passive sub-region 20 and a second passive sub-region 30, which are located on opposite sides of the active region 10 along the first direction X, i.e., the active region 10 is located between the first passive sub-region 20 and the second passive sub-region 30.

[0053] In some embodiments, the first passive sub-region 20 includes a first gap region 21 and a first busbar region 22, and the second passive sub-region 30 includes a second gap region 35 and a second busbar region 36. The first gap region 21 and the second gap region 35 are respectively located on opposite sides of the active region 10 along the first direction X, the first busbar region 22 is located on the side of the first gap region 21 away from the active region 10, and the second busbar region 36 is located on the side of the second gap region 35 away from the active region 10.

[0054] The interdigitated transducer 3 includes multiple electrode fingers, each extending along a first direction X, and the multiple electrode fingers are spaced apart along a second direction Y. The thickness direction Z, the first direction X, and the second direction Y are perpendicular to each other. The multiple electrode fingers overlap along the second direction Y in the active region 10.

[0055] In some embodiments, as shown in FIG3, the interdigital transducer 3 further includes a first busbar 33 and a second busbar 34. The first busbar 33 is located in the first busbar region 22 and extends along the second direction Y. The second busbar 34 is located in the second busbar region 36 and extends along the second direction Y.

[0056] The plurality of electrode fingers includes a first electrode finger 31 and a second electrode finger 32 that are alternately and spaced apart along the second direction Y. The first electrode finger 31 extends from the active region 10 along the first direction X to the first gap region 21 and is connected to the first busbar 33, that is, the first electrode finger 31 is located in the active region 10 and the first gap region 21. The second electrode finger 32 extends from the active region 10 along the first direction X to the second gap region 35 and is connected to the second busbar 34, that is, the second electrode finger 32 is located in the active region 10 and the second gap region 35.

[0057] The number of first electrode fingers 31 and second electrode fingers 32 can be the same. The dimensions of the first electrode fingers 31 and second electrode fingers 32 (including their length along the first direction X and their width along the second direction Y, etc.) can be the same. The materials of the first electrode fingers 31 and second electrode fingers 32 can each include metallic materials such as copper or aluminum. The first busbar 33 and second busbar 34 can serve as connecting lines to adjacent resonators or connecting lines to the package side. The materials of the first busbar 33 and second busbar 34 can each include metallic materials such as copper or aluminum.

[0058] The interdigital transducer 3 has reflection structures on opposite sides along the second direction Y. These reflection structures reflect surface acoustic waves excited within the resonator back to the active region. At least a portion of the reflection structure on at least one side of the interdigital transducer 3 along the second direction Y is a groove structure 4. The groove structure 4 is located within the piezoelectric layer 2, extending from the upper surface of the piezoelectric layer 2 (i.e., the surface of the piezoelectric layer 2 closest to the interdigital transducer 3) along the thickness direction Z within the piezoelectric layer 2. The groove structure 4 can extend along the thickness direction Z into the interior of the piezoelectric layer 2, or it can penetrate the piezoelectric layer 2 along the thickness direction Z.

[0059] The groove structure 4 has a first groove wall 41 and a second groove wall 42 connected to each other on the side near the interdigital transducer 3. The first groove wall 41 is correspondingly disposed to the active region 10 and extends along the first direction X, that is, the first groove wall 41 is disposed parallel to the electrode fingers in the interdigital transducer 3. The length of the first groove wall 41 along the first direction X can be the same as the length of the active region 10 along the first direction X.

[0060] At least a portion of the second trench wall 42 is disposed corresponding to the passive region, and the second trench wall 42 is inclined away from the interdigital transducer 3, that is, the second trench wall 42 is not parallel to the electrodes in the interdigital transducer 3. The length of the second trench wall 42 along the first direction X can be greater than or equal to the length of the passive region along the first direction X.

[0061] In related technologies, interdigital transducers in surface acoustic wave (SAW) resonators have reflective gratings on opposite sides along the second direction. These gratings reflect acoustic wave energy back to the active region. However, the reflection is incomplete, and some SAW crosstalk occurs to other resonators (such as adjacent resonators), causing interference. The intensity of this interference is related to the total reflectivity of the grating and the distance between the two resonators. The greater the distance between the two resonators, the greater the total reflectivity of the grating and the smaller the interference intensity. The total reflectivity of the grating is related to the number of reflective strips and the reflectivity of a single strip. The formula for the total reflectivity P11 of the grating is: P11=re×sin(q×Nr×pitch) / (q×cos(q×Nr×pitch)+i×δ×sin(q×Nr×pitch)).

[0062] Where re is the reflectivity of a single reflective strip in the grating, Nr is the number of reflective strips in the grating, and q is the dispersion relation. k is the reflectivity, δ is the normalized wave vector, and pitch is the period of the reflection strip.

[0063] To reflect most of the acoustic wave energy back to the active region and reduce interference to other resonators, the number of reflective strips in the reflective grating can be increased, thereby increasing the total reflectivity of the reflective grating. Figure 5 shows the case of P11 when the number of reflective strips Nr in the reflective grating is 20, 30, and 40, respectively, using the P-matrix model (assuming re = 0.05). As can be seen from Figure 5, 20 reflective strips in the reflective grating are insufficient for total reflection of surface acoustic waves, while more than 30 reflective strips in the reflective grating result in relatively small crosstalk to other resonators.

[0064] However, setting the number of reflective strips in the reflective grating to more than 30 results in a large space occupied by the reflective grating, which in turn leads to a larger resonator size. In addition, the surface acoustic waves excited in the active region of the resonator are stronger than those excited in the passive region, and the surface acoustic waves excited in the active region are mainly the dominant mode, while the passive region also excites some stray modes (such as the transverse mode TM), causing some spurious signals in the passband of the resonator and affecting the performance of the resonator.

[0065] In this embodiment, at least a portion of the reflection structure on at least one side of the interdigital transducer 3 along the second direction Y is replaced by a groove structure 4. The abrupt change in acoustic impedance at the boundary of the groove structure 4 causes the surface acoustic waves excited by the resonator to reflect at the boundary of the groove structure 4. Figure 6 shows the P11 case simulation using the P-matrix model when the reflection structures are a reflective grating (with 20, 30, and 40 reflection strips) and a groove structure, respectively. As can be seen from Figure 6, the groove structure 4 has a stronger reflection effect, equivalent to that of a reflective grating with more than 30 reflection strips, and it provides broadband reflection. Therefore, the groove structure 4 can replace the reflective grating, and the width of the groove structure 4 does not need to be too large, making the space occupied by the groove structure 4 much smaller than that occupied by the reflective grating, thereby reducing the volume of the resonator. Furthermore, the groove structure 4 has a first groove wall 41 on the side near the interdigital transducer 3, corresponding to the active region 10. The first groove wall 41 extends along the first direction X to reflect the stronger dominant mode acoustic waves generated in the active region 10 back to the active region, resulting in a strong reflection effect and reducing interference to other resonators. Moreover, the groove structure 4 also has a second groove wall 42 on the side near the interdigital transducer 3, at least partially corresponding to the passive region. The second groove wall 42 is inclined away from the interdigital transducer 3 to scatter stray surface acoustic waves from the passive region to the outside of the resonator, thereby suppressing stray modes within the resonator and improving the resonator's performance.

[0066] In some embodiments, as shown in FIG4, at least some of the reflective structures on opposite sides of the interdigital transducer 3 along the second direction Y are groove structures 4.

[0067] For example, in the second direction Y, which is the left-right direction, groove structures 4 are respectively provided on the left and right sides of the interdigital transducer 3, that is, all the reflection structures on the left and right sides of the interdigital transducer 3 are groove structures 4. The groove structure 4 on the left side of the interdigital transducer 3 has a first groove wall 41 corresponding to the active region 10 and a second groove wall 42 at least partially corresponding to the passive region on the side closer to the interdigital transducer 3 (i.e., the right side). The first groove wall 41 extends along the first direction X to reflect the surface acoustic wave propagating to the left back to the active region 10. The second groove wall 42 is inclined to the left to scatter the stray sound wave propagating to the left to the outside of the resonator and suppress the stray sound in the resonator.

[0068] The groove structure 4 on the right side of the interdigital transducer 3 has a first groove wall 41 corresponding to the active region 10 and a second groove wall 42 at least partially corresponding to the passive region. The first groove wall 41 extends along the first direction X to reflect the surface acoustic wave propagating to the right back to the active region 10. The second groove wall 42 is inclined to the right to scatter the stray sound wave propagating to the right to the outside of the resonator and suppress strays in the resonator.

[0069] In some embodiments, as shown in FIG3, at least a portion of the reflective structure on one side of the interdigital transducer 3 along the second direction Y is a groove structure 4, and the reflective structure on the other side is a reflective grating 5. The reflective grating 5 is disposed in the same layer as the interdigital transducer 3.

[0070] For example, a reflective grating 5 is provided on the left side of the interdigital transducer 3, and a groove structure 4 is provided on the right side. That is, all the reflective structures on the left side of the interdigital transducer 3 are reflective grating 5, and all the reflective structures on the right side are groove structure 4. The reflective grating 5 on the left side of the interdigital transducer 3 includes multiple reflective strips spaced at intervals along the second direction Y. The reflective strips in the reflective grating 5 can be set to more than 30 to reflect the surface acoustic waves propagating to the left back to the active region 10.

[0071] The groove structure 4 on the right side of the interdigital transducer 3 has a first groove wall 41 corresponding to the active region 10 and a second groove wall 42 at least partially corresponding to the passive region. The first groove wall 41 extends along the first direction X to reflect the surface acoustic wave propagating to the right back to the active region 10. The second groove wall 42 is inclined to the right to scatter the stray sound wave propagating to the right to the outside of the resonator and suppress strays in the resonator.

[0072] In some embodiments, the reflective structure of at least one of the opposite sides of the interdigital transducer 3 along the second direction Y is a groove structure 4 and a reflective grating 5 disposed along the second direction Y, that is, the reflective structure of at least one of the opposite sides of the interdigital transducer 3 along the second direction Y is composed of the groove structure 4 and the reflective grating 5. The number of reflective strips of the reflective grating 5 is less than the target number (e.g., 10 strips).

[0073] For example, the left-side reflective structure of the interdigital transducer 3 is composed of a groove structure 4 and a reflective grating 5, while the right-side reflective structure can be either a groove structure 4 or a reflective grating 5. Alternatively, the right-side reflective structure of the interdigital transducer 3 is composed of a groove structure 4 and a reflective grating 5, while the left-side reflective structure can be either a groove structure 4 or a reflective grating 5. Or, the left-side reflective structure of the interdigital transducer 3 is composed of a groove structure 4 and a reflective grating 5, and the right-side reflective structure is also composed of a groove structure 4 and a reflective grating 5.

[0074] When the reflective structure consists of a groove structure 4 and a reflective grating 5, the arrangement order of the groove structure 4 and the reflective grating 5 along the second direction Y is not specifically limited. The groove structure 4 can be positioned closer to the interdigital transducer 3 than the reflective grating 5, i.e., the groove structure 4 is located between the interdigital transducer 3 and the reflective grating 5. Alternatively, the reflective grating 5 can be positioned closer to the interdigital transducer 3 than the groove structure 4, i.e., the reflective grating 5 is located between the interdigital transducer 3 and the groove structure 4.

[0075] In this embodiment, the groove structure 4 can replace part of the reflective grating in the related technology, and the width of the groove structure 4 is smaller than the width of the replaced reflective grating, thereby reducing the space occupied by the reflective structure and thus reducing the volume of the resonator.

[0076] In some embodiments, the passive region includes a first passive sub-region 20 and a second passive sub-region 30 located on opposite sides of the active region 10 along the first direction X. The second trench wall 42 includes a first sub-wall 42a that is at least partially corresponding to the first passive sub-region 20 and a second sub-wall 42b that is at least partially corresponding to the second passive sub-region 30. The first sub-wall 42a and the second sub-wall 42b are respectively connected to opposite sides of the first trench wall 41 along the first direction X, and the first sub-wall 42a is inclined in a direction away from the interdigital transducer 3, and the second sub-wall 42b is inclined in a direction away from the interdigital transducer 3.

[0077] The length of the first sub-wall 42a along the first direction X can be greater than or equal to the length of the first passive sub-region 20 along the first direction X. The length of the second sub-wall 42b along the first direction X can be greater than or equal to the length of the second passive sub-region 30 along the first direction X. The first sub-wall 42a and the second sub-wall 42b are respectively arranged non-parallel to the electrodes in the interdigital transducer 3.

[0078] For example, a groove structure 4 is provided on the right side of the interdigital transducer 3. The left side of the groove structure 4 has a first groove wall 41 corresponding to the active region 10, a first sub-wall 42a at least partially corresponding to the first passive sub-region 20, and a second sub-wall 42b at least partially corresponding to the second passive sub-region 30. The end of the first sub-wall 42a near the first groove wall 41 is connected to the first groove wall 41, and the end of the first sub-wall 42a away from the first groove wall 41 is inclined to the right. The end of the second sub-wall 42b near the first groove wall 41 is connected to the first groove wall 41, and the end of the second sub-wall 42b away from the first groove wall 41 is inclined to the right.

[0079] For example, the interdigital transducer 3 has a groove structure 4 on its left side. The right side of this groove structure 4 has a first groove wall 41 corresponding to the active region 10, a first sub-wall 42a at least partially corresponding to the first passive sub-region 20, and a second sub-wall 42b at least partially corresponding to the second passive sub-region 30. The end of the first sub-wall 42a closest to the first groove wall 41 is connected to the first groove wall 41, and the end of the first sub-wall 42a facing away from the first groove wall 41 is inclined to the left. The end of the second sub-wall 42b closest to the first groove wall 41 is connected to the first groove wall 41, and the end of the second sub-wall 42b facing away from the first groove wall 41 is inclined to the left.

[0080] In some embodiments, the angle α1 between the first sub-wall 42a and the direction away from the interdigital transducer 3 is 45° to 75°, for example, the angle α1 can be 60°. The angle α2 between the second sub-wall 42b and the direction away from the interdigital transducer 3 is 45° to 75°, for example, the angle α2 can be 60°. The angles α1 and α2 can be the same or different.

[0081] In this embodiment, the included angles α1 and α2 should not be too large to avoid weakening the scattering effect on the stray surface acoustic waves in the passive region. The included angles α1 and α2 should also not be too small to avoid the width of the groove structure 4 corresponding to the passive region being too small, which would affect the overall reflection effect of the groove structure 4.

[0082] In some embodiments, the groove structure 4 has a third groove wall 43 on the side opposite to the interdigital transducer 3, which is at least partially corresponding to the active region 10 and the passive region, and the third groove wall 43 extends along the first direction X.

[0083] The length of the third groove wall 43 along the first direction X can be greater than or equal to the total length of the active region 10, the first passive sub-region 20, and the second passive sub-region 30 along the first direction X. The shape of the third groove wall 43 is not specifically limited. For example, the third groove wall 43 can extend along the first direction X to simplify the manufacturing process of the third groove wall 43.

[0084] In some embodiments, as shown in FIG7, the groove structure 4 includes a plurality of grooves 40 spaced apart along the second direction Y. The target groove 40a among the plurality of grooves 40 has a first groove wall 41 and a second groove wall 42 on the side near the interdigital transducer 3, and the target groove 40a is the groove closest to the interdigital transducer 3 among the plurality of grooves 40.

[0085] The first groove wall 41 of the target groove 40a extends along the first direction X, and the second groove wall 42 of the target groove 40a includes a first sub-wall 42a that is at least partially corresponding to the first passive sub-region 20 and a second sub-wall 42b that is at least partially corresponding to the second passive sub-region 30. The first sub-wall 42a and the second sub-wall 42b are respectively connected to opposite sides of the first groove wall 41 along the first direction X, and the first sub-wall 42a is inclined in a direction away from the interdigital transducer 3, and the second sub-wall 42b is inclined in a direction away from the interdigital transducer 3.

[0086] The length of the third groove wall 43 on the side of the target groove 40a away from the interdigital transducer 3 along the first direction X can be greater than or equal to the total length of the active region 10, the first passive sub-region 20, and the second passive sub-region 30 along the first direction X. The shape of the third groove wall 43 on the side of the target groove 40a away from the interdigital transducer 3 is not specifically limited, for example, it can extend along the first direction X.

[0087] The shape of the groove walls on opposite sides along the second direction Y of the plurality of grooves 40, excluding the target groove 40a, is not specifically limited. The length of the plurality of grooves 40, excluding the target groove 40a, along the first direction X, is not specifically limited.

[0088] The dimensions of the plurality of grooves 40 (such as depth along the thickness direction Z, length along the first direction X, and / or width along the second direction Y) may be the same or different. The shapes of the cross-sections of the plurality of grooves 40 parallel to the first direction X and the second direction Y may be the same or different. The shape of the cross-section of each groove 40 parallel to the thickness direction Z and the second direction Y may be rectangular or inverted trapezoidal, etc., and the shapes of the cross-sections of the plurality of grooves 40 parallel to the thickness direction Z and the second direction Y may be the same or different.

[0089] When the reflection structures on opposite sides of the interdigital transducer 3 along the second direction Y are groove structures 4, the number of grooves 40 in the two groove structures 4 can be the same or different.

[0090] In some embodiments, the groove walls on opposite sides of the plurality of grooves 40 extend along the first direction X, respectively.

[0091] The size and shape of the other grooves 40 besides the target groove 40a can be the same. The cross-section of the other grooves parallel to the first direction X and the second direction Y can be rectangular to simplify the manufacturing process of the other grooves.

[0092] In some embodiments, when the surface acoustic wave resonator is a NORMAL-SAW, as shown in FIG1, the surface acoustic wave resonator includes a piezoelectric layer 2, an interdigital transducer 3, and a reflective structure, excluding the substrate. The depth of the groove structure 4 is 0.5λ to 2λ, where λ is the wavelength, the width of the groove structure 4 along the second direction Y is greater than 0.25λ, and the length of the groove structure 4 along the first direction X is greater than or equal to the length of the interdigital transducer 3 along the first direction X.

[0093] When the groove structure 4 includes multiple grooves 40, the depth of each groove 40 can be from 0.5λ to 2λ, the width of each groove 40 along the second direction Y can be greater than 0.25λ, and the length of each groove 40 along the first direction X can be greater than or equal to the length of the interdigital transducer 3 along the first direction X.

[0094] Figure 8 shows the simulated S21 response curve of a surface acoustic wave (SAW) resonator (with reflection gratings on opposite sides of the interdigital transducer along the second direction) in related technologies. The SAW resonator (i.e., resonator one) was electrically excited, and signal detection was performed at the adjacent SAW resonator (i.e., resonator two). The distance between resonators one and two was 2λ. As can be seen from Figure 8, the maximum S21 value is -20dB, indicating that a large amount of SAW from resonator one propagates to resonator two, meaning the reflection effect in resonator one is poor, causing interference to resonator two.

[0095] Figure 9 shows the S21 response curves of the groove structure 4 of the surface acoustic wave resonator in this embodiment at different depths. The width of the groove structure 4 is 0.75λ, and the length of the groove structure 4 is 20λ. As can be seen from Figure 9, when the depth of the groove structure 4 is 0.5λ, the maximum value of S21 is less than -30dB, indicating that the groove structure 4 effectively reflects the surface acoustic waves excited in the resonator, reducing interference to other resonators. The reflection effect of the groove structure 4 is even better at the depths of 1.5λ and 2.5λ.

[0096] Figure 10 shows the S21 response curve of the groove structure 4 of the surface acoustic wave resonator in this embodiment when the depth is 1.5λ, the length is 20λ, and the width is 0.25λ. As can be seen from Figure 10, the maximum value of S21 is less than -40dB. When the width of the groove structure 4 is 0.25λ, the reflection effect of the groove structure 4 is further improved, effectively reducing interference to other resonators.

[0097] In some embodiments, when the surface acoustic wave resonator is a POI-SAW, as shown in FIG2, the surface acoustic wave resonator further includes a substrate 1, which is located on the side of the piezoelectric layer 2 away from the interdigital transducer 3. The substrate 1 may include materials such as monocrystalline silicon, silicon carbide, or sapphire. The depth of the groove structure 4 is 0.25h to 1h, where h is the thickness of the piezoelectric layer 2, the width of the groove structure 4 along the second direction Y is greater than 0.25λ, where λ is the wavelength, and the length of the groove structure 4 along the first direction X is greater than or equal to the length of the interdigital transducer 3 along the first direction X.

[0098] In the case where the groove structure 4 includes multiple grooves 40, the depth of each groove 40 can be from 0.25h to 1h, the width of each groove 40 along the second direction Y can be greater than 0.25λ, and the length of each groove 40 along the first direction X can be greater than or equal to the length of the interdigital transducer 3 along the first direction X.

[0099] In some embodiments, the groove walls of the groove structure 4 are at least one of planar, serrated, and wavy shapes. The first groove wall 41, the first sub-wall 42a, the second sub-wall 42b, the third groove wall 43, and the groove walls on opposite sides along the first direction X can each be at least one of planar, serrated, and wavy shapes. The shapes of the different groove walls of the groove structure 4 can be the same or different.

[0100] It should be noted that the surface acoustic wave resonator in the embodiments of this application can be applied to various acoustic devices, such as radio frequency filters, duplexers, delay lines, frequency discriminators, and modulators.

[0101] According to the surface acoustic wave resonator provided in the embodiments of this application, by setting at least a portion of the reflection structure on at least one side of the interdigital transducer 3 along the second direction Y as a groove structure 4, and the groove structure 4 is located in the piezoelectric layer 2, the reflection of surface acoustic waves is achieved by utilizing the abrupt change in acoustic impedance at the boundary of the groove structure 4. The width of the groove structure 4 does not need to be set too large, reducing the space occupied by the reflection structure, thereby reducing the volume of the resonator and increasing the degree of design freedom. The side of the groove structure 4 near the interdigital transducer 3 has a first groove wall 41 corresponding to the active region 10. The first groove wall 41 extends along the first direction X to reflect the main mode acoustic wave generated by the active region 10 back to the active region 10. The reflection effect is strong, reducing interference to other resonators. The side of the groove structure 4 near the interdigital transducer 3 also has at least a portion of a second groove wall 42 corresponding to the passive region. The second groove wall 42 is inclined in the direction away from the interdigital transducer 3 to scatter the stray mode acoustic wave generated by the passive region to the outside of the resonator, thereby suppressing stray modes and improving the performance of the resonator.

[0102] Accordingly, embodiments of this application also provide a filter.

[0103] As shown in Figure 11, the filter provided in this embodiment includes a plurality of surface acoustic wave resonators spaced at intervals along the second direction Y. The surface acoustic wave resonators are the same as those in the above embodiment, and will not be described in detail here.

[0104] At least some of the reflection structures between the interdigital transducers 3 of at least some adjacent surface acoustic wave resonators are groove structures 4. That is, at least some of the reflection structures between the interdigital transducers 3 of some adjacent surface acoustic wave resonators are groove structures 4, or at least some of the reflection structures between the interdigital transducers 3 of all adjacent surface acoustic wave resonators are groove structures 4.

[0105] For example, the left-side reflection structure of the first surface acoustic wave (SAW) resonator (e.g., the leftmost SAW resonator) in a plurality of SAW resonators can be a reflection grating 5 or a groove structure 4. The right-side reflection structure of the last SAW resonator (e.g., the rightmost SAW resonator) in a plurality of SAW resonators can be a reflection grating 5 or a groove structure 4. The left and right reflection structures of all SAW resonators except the first and last SAW resonators in a plurality of SAW resonators can be groove structures 4.

[0106] Two groove structures 4 can be set between the interdigital transducers 3 of adjacent surface acoustic wave resonators, or they can share a single groove structure 4.

[0107] The groove structure 4 has a strong reflection effect. At least part of the reflection structure between the interdigital transducers 3 of adjacent surface acoustic wave resonators is set as groove structure 4, which can effectively reduce crosstalk between adjacent surface acoustic wave resonators. Moreover, the arrangement between adjacent surface acoustic wave resonators is more compact, which effectively reduces the spacing between adjacent surface acoustic wave resonators and reduces the size of the filter.

[0108] In some embodiments, as shown in FIG12, the interdigital transducers 3 of adjacent surface acoustic wave (SAW) resonators include a first interdigital transducer 3a and a second interdigital transducer 3b. That is, adjacent SAW resonators include a first SAW resonator and a second SAW resonator, the first SAW resonator includes a first interdigital transducer 3a, and the second SAW resonator includes a second interdigital transducer 3b. The first interdigital transducer 3a and the second interdigital transducer 3b may share a common groove structure 4.

[0109] The groove structure 4 has a first groove wall 41 corresponding to the active region 10 of the first interdigital transducer 3a and a second groove wall 42 at least partially corresponding to the passive region of the first interdigital transducer 3a on the side near the first interdigital transducer 3a. The first groove wall 41 extends along a first direction X, and the length of the first groove wall 41 along the first direction X can be the same as the length of the active region 10 of the first interdigital transducer 3a along the first direction X, so as to reflect the main mode acoustic wave generated by the active region 10 of the first interdigital transducer 3a back to the active region 10 of the first interdigital transducer 3a, thereby reducing interference to the second surface acoustic wave resonator. The second groove wall 42 is inclined in a direction away from the first interdigital transducer 3a (e.g., to the right). The length of the second groove wall 42 along the first direction X is greater than or equal to the length of the passive region of the first interdigital transducer 3a along the first direction X, so as to scatter the stray mode sound waves generated by the passive region of the first interdigital transducer 3a to the outside of the first surface acoustic wave resonator and suppress strays in the first surface acoustic wave resonator.

[0110] The groove structure 4 has a first groove wall 41 corresponding to the active region 10 of the second interdigital transducer 3b and a second groove wall 42 at least partially corresponding to the passive region of the second interdigital transducer 3b on the side near the second interdigital transducer 3b. The first groove wall 41 extends along a first direction X, and the length of the first groove wall 41 along the first direction X can be the same as the length of the active region 10 of the second interdigital transducer 3b along the first direction X, so as to reflect the main mode acoustic wave generated by the active region 10 of the second interdigital transducer 3b back to the active region 10 of the second interdigital transducer 3b, thereby reducing interference to the first surface acoustic wave resonator. The second groove wall 42 is inclined in a direction away from the second interdigital transducer 3b (e.g., to the left). The length of the second groove wall 42 along the first direction X is greater than or equal to the length of the passive region of the second interdigital transducer 3b along the first direction X, so as to scatter the stray mode acoustic waves generated by the passive region of the second interdigital transducer 3b to the outside of the second surface acoustic wave resonator and suppress strays in the second surface acoustic wave resonator.

[0111] The inclination angles of the second groove wall 42 on the side of the groove structure 4 near the first interdigital transducer 3a and the second groove wall 42 on the side of the groove structure 4 near the second interdigital transducer 3b can be different.

[0112] The reflective structure of the first interdigital transducer 3a on the side opposite to the second interdigital transducer 3b can be a reflective grating or a groove structure 4. The reflective structure of the second interdigital transducer 3a on the side opposite to the first interdigital transducer 3b can also be a reflective grating or a groove structure 4.

[0113] In some embodiments, the active region 10 of the first interdigital transducer 3a and the active region 10 of the second interdigital transducer 3b have the same or different lengths along the first direction X.

[0114] To meet requirements such as impedance matching, the parameters between adjacent surface acoustic wave resonators (such as the length of the active region 10 along the first direction X) will be different. That is, the active region 10 of the first interdigital transducer 3a and the active region 10 of the second interdigital transducer 3b can have different lengths along the first direction X, and the first groove wall 41 of the groove structure 4 near the first interdigital transducer 3a and the first groove wall 41 of the groove structure 4 near the second interdigital transducer 3b can have different lengths along the first direction X.

[0115] According to the filter provided in the embodiments of this application, by setting at least a portion of the reflection structure between the interdigital transducers 3 of at least some adjacent surface acoustic wave (SAW) resonators as a groove structure 4, crosstalk between adjacent SAW resonators can be effectively reduced, the spacing between adjacent SAW resonators can be reduced, the size of the filter can be reduced, and the design freedom can be increased. The groove structure 4 has a second groove wall 42 on the side near each interdigital transducer 3, corresponding to the passive region of each interdigital transducer 3. The second groove wall 42 is inclined away from each interdigital transducer 3 to scatter the stray mode acoustic waves generated by the passive region of each interdigital transducer 3 to the outside of the resonator, thereby suppressing stray modes within each SAW resonator and improving the performance of the filter.

[0116] Accordingly, this application also provides an electronic device including the filter described in the above embodiments, which will not be described in detail here.

[0117] According to the electronic device provided in the embodiments of this application, by setting at least a portion of the reflective structure on at least one side of the interdigital transducer along the second direction as a groove structure, and the groove structure is located in the piezoelectric layer, the space occupied by the reflective structure is reduced, thereby reducing the volume of the resonator. The side of the groove structure near the interdigital transducer has a first groove wall corresponding to the active region. The first groove wall extends along the first direction to reflect the main mode sound wave generated by the active region back to the active region. The reflection effect is strong, reducing crosstalk between resonators. The side of the groove structure near the interdigital transducer also has at least a portion of a second groove wall corresponding to the passive region. The second groove wall is inclined in the direction away from the interdigital transducer to scatter the stray mode sound wave generated by the passive region to the outside of the resonator, thereby suppressing stray modes in the resonator and improving the performance of the electronic device.

[0118] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and are not limited in number; for example, a first object can be one or more.

[0119] In the description of this application, "multiple" means two or more.

[0120] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0121] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A surface acoustic wave resonator, characterized in that, include: piezoelectric layer; An interdigital transducer is located on one side of the piezoelectric layer in the thickness direction; the interdigital transducer includes an active region and passive regions located on opposite sides of the active region along a first direction; The interdigital transducer has a reflective structure on each of its opposite sides along the second direction, and at least a portion of the reflective structure on at least one side of the opposite sides of the interdigital transducer along the second direction is a groove structure, the groove structure being located in the piezoelectric layer; the thickness direction, the first direction, and the second direction are perpendicular to each other; The groove structure has a first groove wall corresponding to the active region and a second groove wall at least partially corresponding to the passive region on the side near the interdigital transducer. The first groove wall extends along the first direction, and the second groove wall is connected to the first groove wall and inclined in a direction away from the interdigital transducer.

2. The surface acoustic wave resonator according to claim 1, characterized in that, The interdigital transducer has at least a portion of its reflective structures on opposite sides along the second direction as groove structures; or, At least a portion of the reflective structure on one side of the interdigital transducer along the second direction is the groove structure, and the reflective structure on the other side of the interdigital transducer along the second direction is a reflective grating, wherein the reflective grating is disposed in the same layer as the interdigital transducer; or, The reflective structure of at least one of the opposite sides of the interdigital transducer along the second direction is a groove structure and a reflective grating arranged along the second direction.

3. The surface acoustic wave resonator according to claim 1 or 2, characterized in that, The passive region includes a first passive sub-region and a second passive sub-region located on opposite sides of the active region along the first direction. The second tank wall includes a first sub-wall that is at least partially corresponding to the first passive sub-region and a second sub-wall that is at least partially corresponding to the second passive sub-region. The first sub-wall and the second sub-wall are respectively connected to the opposite sides of the first groove wall along the first direction, and the first sub-wall is inclined in the direction away from the interdigital transducer, and the second sub-wall is inclined in the direction away from the interdigital transducer.

4. The surface acoustic wave resonator according to claim 3, characterized in that, The angle between the first sub-wall and the direction away from the interdigital transducer is 45° to 75°, and the angle between the second sub-wall and the direction away from the interdigital transducer is 45° to 75°.

5. The surface acoustic wave resonator according to any one of claims 1 to 4, characterized in that, The groove structure has a third groove wall on the side opposite to the interdigital transducer, which is at least partially corresponding to the active region and the passive region, and the third groove wall extends along the first direction.

6. The surface acoustic wave resonator according to any one of claims 1 to 5, characterized in that, The groove structure includes a plurality of grooves spaced apart along the second direction; The target groove among the plurality of grooves has a first groove wall and a second groove wall on the side near the interdigital transducer, and the target groove is the groove closest to the interdigital transducer among the plurality of grooves.

7. The surface acoustic wave resonator according to claim 6, characterized in that, The other grooves in the plurality of grooves extend along the first direction from the groove walls on opposite sides of the second direction.

8. The surface acoustic wave resonator according to any one of claims 1 to 7, characterized in that, The groove structure has a depth of 0.5λ to 2λ along the thickness direction, where λ is the wavelength. The width of the groove structure along the second direction is greater than 0.25λ. The length of the groove structure along the first direction is greater than or equal to the length of the interdigital transducer along the first direction.

9. The surface acoustic wave resonator according to any one of claims 1 to 7, characterized in that, The surface acoustic wave resonator also includes a substrate, which is located on the side of the piezoelectric layer away from the interdigital transducer; The groove structure has a depth of 0.25h to 1h along the thickness direction, where h is the thickness of the piezoelectric layer. The width of the groove structure along the second direction is greater than 0.25λ, where λ is the wavelength. The length of the groove structure along the first direction is greater than or equal to the length of the interdigital transducer along the first direction.

10. The surface acoustic wave resonator according to any one of claims 1 to 9, characterized in that, The groove wall of the groove structure is at least one of planar, serrated, and wavy, and the groove wall includes at least the first groove wall or the second groove wall.

11. A filter, characterized in that, It includes a plurality of surface acoustic wave resonators spaced apart along a second direction, wherein the surface acoustic wave resonators are surface acoustic wave resonators as described in any one of claims 1 to 10; At least a portion of the reflection structure between the interdigital transducers of at least some adjacent surface acoustic wave resonators is the groove structure.

12. The filter according to claim 11, characterized in that, The interdigital transducers adjacent to the surface acoustic wave resonator include a first interdigital transducer and a second interdigital transducer. The groove structure has a first groove wall corresponding to the active region of the first interdigital transducer and a second groove wall corresponding to at least part of the passive region of the first interdigital transducer on the side near the first interdigital transducer; the groove structure also has a first groove wall corresponding to the active region of the second interdigital transducer and a second groove wall corresponding to at least part of the passive region of the second interdigital transducer on the side near the second interdigital transducer.

13. The filter according to claim 12, characterized in that, The active regions of the first interdigital transducer and the active regions of the second interdigital transducer have different lengths along the first direction.

14. The filter according to claim 12 or 13, characterized in that, The length of the first groove wall on the side of the groove structure near the first interdigital transducer is different from that on the side of the groove structure near the second interdigital transducer along the first direction.

15. An electronic device, characterized in that, Includes the filter as described in any one of claims 11 to 14.

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