Surface acoustic wave resonator, filter and multiplexer

Abstract

The embodiment of the invention provides a surface acoustic wave resonator, a filter and a multiplexer. The surface acoustic wave resonator comprises a substrate; the piezoelectric layer is positioned on one side of the substrate; an electrode layer; the piezoelectric layer is located on one side away from the substrate; the electrode layer comprises a plurality of interdigital electrodes; the plurality of interdigital electrodes comprise a plurality of first interdigital electrodes and a plurality of second interdigital electrodes; the first interdigital electrodes and the second interdigital electrodes are sequentially and alternately arranged in the first direction and extend in the second direction. A lateral mode suppression layer; the transverse mode suppression layer at least comprises a first transverse mode suppression layer located between the piezoelectric layer and the electrode layer; in the first direction, the size between any two adjacent first interdigital electrodes and the size between any two adjacent second interdigital electrodes are the same and are lambda; the thickness of the transverse mode suppression layer is h; wherein h is larger than or equal to 0.0025 lambda and smaller than or equal to 0.03 lambda, the transverse mode can be suppressed by arranging the transverse mode suppression layer, and then the performance of the surface acoustic wave resonator is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resonators, in particular to a surface acoustic wave resonator, filter and multiplexer. BACKGROUND

[0002] A surface acoustic wave (SAW) device is an electronic component that works by utilizing the characteristics of sound wave propagation on the surface of a solid, and is widely used in the fields of filters, resonators, etc.

[0003] In a SAW device, transverse mode is a common problem in the process of sound wave propagation, which can cause energy loss, undesirable frequency response and signal distortion, thereby affecting the overall performance of the device. SUMMARY

[0004] The embodiments of the present application provide a surface acoustic wave resonator, filter and multiplexer, which can suppress transverse mode by setting a transverse mode suppression layer, thereby improving the performance of the surface acoustic wave resonator.

[0005] In a first aspect, the embodiments of the present application provide a surface acoustic wave resonator, comprising:

[0006] a substrate;

[0007] a piezoelectric layer located on one side of the substrate;

[0008] an electrode layer located on a side of the piezoelectric layer away from the substrate; the electrode layer comprises a plurality of interdigital electrodes; the plurality of interdigital electrodes comprises a plurality of first interdigital electrodes and a plurality of second interdigital electrodes; the first interdigital electrodes and the second interdigital electrodes are alternately arranged along a first direction and both extend along a second direction; the first direction intersects the second direction;

[0009] a transverse mode suppression layer; the transverse mode suppression layer at least comprises a first transverse mode suppression layer located between the piezoelectric layer and the electrode layer;

[0010] along the first direction, the size between any two adjacent first interdigital electrodes is the same as the size between any two adjacent second interdigital electrodes, and both are λ; the thickness of the transverse mode suppression layer is h;

[0011] wherein 0.0025λ≤h≤0.03λ.

[0012] Optionally, the first transverse mode suppression layer covers the orthographic projection of the piezoelectric layer on the plane of the substrate.

[0013] Optionally, the first transverse mode suppression layer comprises a first groove.

[0014] The first groove penetrates the first transverse mode suppression layer along a thickness direction of the surface acoustic wave resonator.

[0015] Part of the piezoelectric layer is located in the first groove.

[0016] Optionally, the first transverse mode suppression layer comprises a connecting portion and a plurality of protruding portions.

[0017] The protruding portions are located on a side of the connecting portion away from the substrate along a thickness direction of the surface acoustic wave resonator; the plurality of protruding portions are arranged along the first direction and are all connected to the connecting portion.

[0018] The electrode layer is located on a side of the protruding portion away from the substrate.

[0019] Optionally, a projection of the first transverse mode suppression layer on a plane where the substrate is located covers a projection of the interdigital electrode on the plane where the substrate is located.

[0020] Optionally, a projection of the first transverse mode suppression layer on a plane where the substrate is located coincides with a projection of the interdigital electrode on the plane where the substrate is located.

[0021] Optionally, the first transverse mode suppression layer comprises a first surface and a second surface; the first surface is located on a side of the second surface away from the substrate along a thickness direction of the surface acoustic wave resonator.

[0022] The piezoelectric layer comprises a second groove, and the second groove penetrates part of the piezoelectric layer along a thickness direction of the surface acoustic wave resonator; the piezoelectric layer further comprises a third surface and a fourth surface; the third surface is located on a side of the fourth surface away from the substrate along the thickness direction of the surface acoustic wave resonator.

[0023] The first transverse mode suppression layer is located in the second groove, and the first surface is flush with the third surface along the thickness direction of the surface acoustic wave resonator.

[0024] Optionally, the electrode layer comprises at least two electrode sub-layers.

[0025] The at least two electrode sub-layers comprise a first electrode sub-layer and a second electrode sub-layer; the first electrode sub-layer is located on a side of the second electrode sub-layer away from the substrate.

[0026] The transverse mode suppression layer further comprises a second transverse mode suppression layer located between the first electrode sub-layer and the second electrode sub-layer.

[0027] Optionally, a fast transverse wave slowness curve of the transverse mode suppression layer has a curvature γ1, where 0≤γ1≤1.

[0028] Optionally, the material of the piezoelectric layer includes lithium tantalate.

[0029] Secondly, embodiments of the present invention also provide a filter, including at least one series arm resonator and at least one parallel arm resonator;

[0030] At least one of the series arm resonator and the parallel arm resonator includes the surface acoustic wave resonator as described in any of the first aspects.

[0031] Thirdly, embodiments of the present invention also provide a multiplexer, including an antenna terminal, at least one receiving unit, and at least one transmitting unit;

[0032] The antenna terminals are communicatively connected to both the receiving unit and the transmitting unit.

[0033] At least one of the receiving unit and the transmitting unit includes the filter described in the second aspect.

[0034] The technical solution provided in this invention includes a surface acoustic wave (SAW) resonator comprising a transverse mode suppression layer, which at least includes a first transverse mode suppression layer located between the piezoelectric layer and the electrode layer. Along a first direction, the dimension between any two adjacent first interdigital electrodes is the same as the dimension between any two adjacent second interdigital electrodes, and both are λ, meaning the wavelength of the SAW resonator is λ. The wavelength λ and the thickness h of the transverse mode suppression layer satisfy 0.0025λ ≤ h ≤ 0.03λ, which helps ensure a moderate thickness of the transverse mode suppression layer, thereby suppressing transverse modes and improving the performance of the SAW resonator. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0036] Figure 1 A top view schematic diagram of a surface acoustic wave resonator provided in the prior art;

[0037] Figure 2 for Figure 1 A schematic diagram of the first cross-sectional structure of the corresponding surface acoustic wave resonator along the section line A-A';

[0038] Figure 3 for Figure 1 The corresponding horizontal shear wave slowness curve of the surface acoustic wave resonator;

[0039] Figure 4 for Figure 1 Schematic diagram of admittance, conductance and frequency curves of the corresponding surface acoustic wave resonator;

[0040] Figure 5 A top view schematic diagram of a surface acoustic wave resonator provided in an embodiment of the present invention;

[0041] Figure 6 for Figure 5 A schematic diagram of the first cross-sectional structure of the corresponding surface acoustic wave resonator along section line B-B'.

[0042] Figure 7 The diagram shows the horizontal shear wave slowness curve when h < 0.0025λ in the surface acoustic wave resonator provided in the embodiment of the present invention.

[0043] Figure 8 This is a schematic diagram of the admittance, conductance, and frequency curves of a surface acoustic wave resonator provided in an embodiment of the present invention when h > 0.03λ.

[0044] Figure 9 for Figure 5 A schematic diagram showing the relationship between the curvature of the slowness curve of the corresponding surface acoustic wave resonator and the ratio of the thickness to the wavelength of the transverse mode suppression layer;

[0045] Figure 10 for Figure 5 The corresponding horizontal shear wave slowness curve of the surface acoustic wave resonator;

[0046] Figure 11 for Figure 5 Schematic diagram of admittance, conductance and frequency curves of the corresponding surface acoustic wave resonator;

[0047] Figure 12 This is a diagram showing the horizontal shear wave slowness curve of a surface acoustic wave resonator when γ1 > 1, provided in an embodiment of the present invention.

[0048] Figure 13 The horizontal shear wave slowness curve of the surface acoustic wave resonator when the lateral mode suppression layer is located between the piezoelectric layer and the substrate, as provided in the embodiments of the present invention;

[0049] Figure 14 for Figure 5 A schematic diagram of the second cross-sectional structure of the corresponding surface acoustic wave resonator along section line B-B';

[0050] Figure 15 for Figure 5 A schematic diagram of the third cross-sectional structure of the corresponding surface acoustic wave resonator along section line B-B'.

[0051] Figure 16 forFigure 5 A schematic diagram of the fourth cross-sectional structure of the corresponding surface acoustic wave resonator along section line B-B'.

[0052] Figure 17 for Figure 5 The corresponding fifth cross-sectional structure of the surface acoustic wave resonator along section line B-B' is shown in the diagram.

[0053] Figure 18 for Figure 5 A schematic diagram of the sixth cross-sectional structure of the corresponding surface acoustic wave resonator along section line B-B';

[0054] Figure 19 for Figure 5 The corresponding seventh cross-sectional structure of the surface acoustic wave resonator along section line B-B' is shown in the diagram.

[0055] Figure 20 for Figure 5 The corresponding eighth cross-sectional structure of the surface acoustic wave resonator along section line B-B' is shown in the diagram.

[0056] Figure 21 A schematic diagram of a filter structure provided in an embodiment of the present invention;

[0057] Figure 22 This is a schematic diagram of a multiplexer provided in an embodiment of the present invention. Detailed Implementation

[0058] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0059] In this invention, unless otherwise expressly specified and limited, the first feature "above" or "below" the second feature may include direct contact between the first and second features, or contact between the first and second features not in direct contact but through another feature between them.

[0060] In the description of this embodiment, the terms "upper" and "lower," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the system or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for descriptive distinction and have no special meaning.

[0061] Before describing the technical solutions of the embodiments of the present invention in detail, the surface acoustic wave resonator in the prior art will be described in detail.

[0062] Figure 1 This is a top view schematic diagram of a surface acoustic wave resonator provided in the prior art. Figure 2 for Figure 1 The corresponding schematic diagram of the first type of cross-sectional structure of the surface acoustic wave resonator along section line A-A' is shown below. Figure 1 and Figure 2 As shown, the surface acoustic wave resonator 100' includes a substrate 10', a piezoelectric layer 20', and an electrode layer 30'. Figure 3 for Figure 1 The corresponding horizontal shear wave slowness curve of the surface acoustic wave resonator is shown in the figure below. Figure 3 As shown, the horizontal shear wave is the dominant mode of the surface acoustic wave resonator, in S... y The curve at point A1 is convex, meaning the curvature of the slow curve of the surface acoustic wave resonator at point A1 is greater than 0, indicating that the surface acoustic wave resonator has a transverse mode. Figure 4 for Figure 1 The corresponding admittance, conductance, and frequency curves of the surface acoustic wave resonator are shown in the diagram below. Figure 4 As shown, the black curve represents the admittance curve and the red curve represents the conductance curve. In the resonant frequency and anti-resonant frequency range, that is, in the range of 1300MHz-1370MHz, the fluctuations of the admittance and conductance curves are more obvious, which indicates that the surface acoustic wave resonator has a transverse mode.

[0063] To address the aforementioned technical problems, embodiments of the present invention provide at least a transverse mode suppression layer between the piezoelectric layer and the electrode layer to suppress transverse modes, thereby improving the performance of the surface acoustic wave resonator. The technical solutions provided by the embodiments of the present invention will be described in detail below.

[0064] Figure 5 This is a top view schematic diagram of a surface acoustic wave resonator provided in an embodiment of the present invention. Figure 6 for Figure 5 The corresponding schematic diagram of the first cross-sectional structure of the surface acoustic wave resonator along section line B-B' is shown below. Figure 5 and Figure 6 As shown, the surface acoustic wave resonator 100 includes: a substrate 10; a piezoelectric layer 20 located on one side of the substrate 10; an electrode layer 30 located on the side of the piezoelectric layer 20 away from the substrate 10; the electrode layer 30 includes a plurality of interdigital electrodes 301; the plurality of interdigital electrodes 301 includes a plurality of first interdigital electrodes 3011 and a plurality of second interdigital electrodes 3012; the first interdigital electrodes 3011 and the second interdigital electrodes 3012 are aligned along a first direction (e.g., ...). Figure 5 The X directions shown are alternately arranged and all are along the second direction (e.g., Figure 5The first direction X intersects with the second direction Y; a transverse mode suppression layer 40; the transverse mode suppression layer 40 includes at least a first transverse mode suppression layer 401 located between the piezoelectric layer 20 and the electrode layer 30; along the first direction X, the dimension between any two adjacent first interdigital electrodes 3011 is the same as the dimension between any two adjacent second interdigital electrodes 3012 and both are λ; the thickness of the transverse mode suppression layer 40 is h; wherein, 0.0025λ≤h≤0.03λ.

[0065] Specifically, the piezoelectric layer 20 is located on one side of the substrate 10, that is, the piezoelectric layer 20 is located on the upper surface of the substrate 10. In this way, the piezoelectric layer 20 and the substrate 10 can form a piezoelectric composite substrate. Due to the high Q-value performance of piezoelectric composite substrates, they are widely used in many fields such as radar, communication, and navigation. The piezoelectric layer 20 is a thin single-crystal layer made of piezoelectric material. The material of the piezoelectric layer 20 can be lithium niobate, lithium tantalate, gallium nitride, aluminum nitride, or zinc oxide, etc. The piezoelectric layer 20 is cut to align with the crystal axes of the front and back sides of the piezoelectric layer 20, thus allowing for different tangential orientations. These orientations are often defined using Euler angles. For example, the Euler angles of a piezoelectric layer cut at 32°Y are (0°, 122°, 0°), the Euler angles of a piezoelectric layer cut at Z are (0°, 0°, 0°), the Euler angles of a piezoelectric layer cut at 128°Y are (0°, 38°, 0°), and the Euler angles of a piezoelectric layer cut at 32°Y and 45°X are (0°, 122°, 45°).

[0066] Specifically, substrate 10 is a single-layer or multi-layer substrate made of a high-velocity acoustic material, and is therefore also called a high-velocity acoustic layer. The speed of sound of bulk waves propagating in the high-velocity acoustic layer is higher than that of sound waves propagating in the piezoelectric layer, thereby increasing the speed of sound waves in the piezoelectric layer and raising the frequency of the resonator. Furthermore, the high-velocity acoustic layer effectively confines the sound waves propagating in the piezoelectric layer within the piezoelectric layer to prevent leakage, thereby improving the Q value of the resonator. The high-velocity acoustic component is made of materials with high sound speeds, such as silicon, sapphire, silicon carbide, aluminum nitride, or quartz. It should be noted that the quality factor, or Q value, is a measure of energy loss in a resonator. When energy is converted from one form to another, a portion of the energy contained in the system will directly escape or be repeatedly converted into an unrecoverable form of energy.

[0067] Specifically, the electrode layer 30 includes multiple interdigitated electrodes 301, which, together with the busbar 302, form an interdigitated transducer. The interdigitated transducer is located at the center of the surface acoustic wave resonator 100 and is responsible for converting electrical signals to acoustic signals. When an AC signal of a certain frequency is applied to the busbar 302, surface acoustic waves can be generated in the surface acoustic wave resonator 100. The surface acoustic waves are mainly concentrated in the effective aperture region aa and mainly propagate along the first direction X, but some transverse waves also propagate and leak along the second direction Y towards the busbar 302.

[0068] It should be noted that the effective aperture region aa can be the region where multiple first interdigital electrodes 3011 and second interdigital electrodes 3012 overlap along the first direction X.

[0069] Specifically, both the first interdigital electrode 3011 and the second interdigital electrode 3012 can be long finger electrodes, i.e., true finger electrodes. The first interdigital electrode 3011 and the second interdigital electrode 3012 are alternately arranged along the first direction X and both extend along the second direction Y. In this way, multiple first interdigital electrodes 3011 can be electrically connected to the upper first busbar 3021, forming a comb-like shape, and multiple second interdigital electrodes 3012 can be electrically connected to the lower second busbar 3022, forming a comb-like shape, to ensure signal transmission efficiency.

[0070] Specifically, along the first direction X, the dimension between any two adjacent first interdigital electrodes 3011 is the same as the dimension between any two adjacent second interdigital electrodes 3012, and both are λ. That is, along the first direction X, the dimension between any two adjacent first interdigital electrodes 3011 is λ, and the dimension between any two adjacent second interdigital electrodes 3012 is λ, meaning the wavelength of the interdigital transducer is λ. For example, taking the second interdigital electrode 3012 as an example, the distance between the leftmost edge of a certain second interdigital electrode 3012 and the leftmost edge of its adjacent second interdigital electrode 3012 is λ.

[0071] Specifically, the lateral mode suppression layer 40 includes at least a first lateral mode suppression layer 401 located between the piezoelectric layer 20 and the electrode layer 30, that is, the lateral mode suppression layer 40 includes at least a first lateral mode suppression layer 401 located between the piezoelectric layer 20 and the electrode layer 30.

[0072] Specifically, since the transverse mode suppression layer 40 is at least the first transverse mode suppression layer 401, the thickness h of the transverse mode suppression layer 40 can be understood as the total thickness.

[0073] Optional, continue to refer to Figure 5 and Figure 6 The curvature of the fast transverse wave slow curve of the transverse mode suppression layer 40 is γ1, where 0≤γ1≤1. That is to say, the transverse mode suppression layer 40 is composed of one or more materials with a certain fast transverse wave curvature, which is beneficial to suppressing the transverse mode and thus improving the performance of the resonator.

[0074] In the following embodiments, the piezoelectric layer 20 is lithium tantalate (LiTaO3), the Euler angle is (0°, 132°, 0°), the thickness of the piezoelectric layer 20 is 600nm, and the wavelength λ of the sound wave is 2μm; the interdigitated electrode 301 is made of aluminum electrode, and the substrate 10 can be a composite substrate formed by stacking a silicon dioxide layer and a polycrystalline silicon layer, with the polycrystalline silicon layer located on the upper surface of the silicon dioxide layer; wherein, the thickness of the silicon dioxide layer is 500nm and the thickness of the polycrystalline silicon layer is 1μm, as an example, for illustration.

[0075] For example, when h < 0.0025λ, the thickness of the transverse mode suppression layer 40 is relatively thin. Figure 7 The diagram shows the horizontal shear wave slowness curve when h < 0.0025λ in the surface acoustic wave resonator provided in this embodiment of the invention. Figure 7 As shown, S y The curve at point A2 is convex, meaning the curvature of the slow curve of the resonator at point A2 is greater than 0, indicating the presence of a transverse mode in the resonator.

[0076] For example, when h > 0.03λ, the thickness of the transverse mode suppression layer 40 is relatively thick. Figure 8 The diagram shows the admittance, conductance, and frequency curves of the surface acoustic wave resonator provided in this embodiment of the invention when h > 0.03λ. Figure 8 As shown, the black curve is the admittance curve and the red curve is the conductance curve. It can be seen that when the thickness of the transverse mode suppression layer 40 is too thick, the admittance ratio and electromechanical coupling coefficient of the admittance curve are greatly reduced, which is detrimental to the design and fabrication of the device.

[0077] The embodiments of the present invention provide a setting of 0.0025λ≤h≤0.03λ, which ensures that the thickness of the transverse mold suppression layer 40 is moderate. Figure 9 for Figure 5 A schematic diagram showing the relationship between the curvature of the slowness curve of the corresponding surface acoustic wave resonator and the ratio of the thickness to the wavelength of the transverse mode suppression layer, as shown below. Figure 9 As shown, when 0.0025λ≤h≤0.03λ, that is, 0.0025≤h / λ≤0.03, i.e. Figure 9 Within the shaded region, the curvature of the slowness curve of the surface acoustic wave resonator is less than or equal to 0. Taking h=10nm and γ1=1 as an example... Figure 10 for Figure 5 The corresponding horizontal shear wave slowness curve of the surface acoustic wave resonator is shown in the figure below. Figure 10 As shown, S y The curve at point A3 is concave, meaning the curvature of the slowness curve of the resonator at point A3 is less than 0. This indicates that the surface acoustic wave resonator does not have transverse modes. Therefore, a transverse mode suppression layer, with a thickness satisfying 0.0025λ ≤ h ≤ 0.03λ, can suppress transverse modes, thereby improving the resonator's performance. Furthermore, Figure 11for Figure 5 The corresponding admittance, conductance, and frequency curves of the surface acoustic wave resonator are shown in the diagram below. Figure 11 As shown, the black curve represents the admittance curve, and the red curve represents the conductance curve. Figure 4 Compared to the admittance curve in the original text, the embodiments of the present invention, by setting a transverse mode suppression layer, can significantly reduce the fluctuation between the resonant frequency and the anti-resonant frequency, i.e. Figure 11 The admittance curve between the intermediate resonant frequency and the anti-resonant frequency is relatively smooth, which enables the suppression of transverse modes.

[0078] For example, when γ1 > 1, it indicates that the curvature of the fast shear wave slowness curve of the transverse mode suppression layer 40 is relatively large. Figure 12 The horizontal shear wave slowness curve of the surface acoustic wave resonator when γ1 > 1 is provided in the embodiments of the present invention, as shown in the figure. Figure 12 As shown, taking γ1=2.3 as an example, in S y The curve at point A4 is convex, meaning the curvature of the slow curve of the surface acoustic wave resonator at point A4 is greater than 0, indicating that the surface acoustic wave resonator has a transverse mode.

[0079] As a comparative example, when the transverse mode suppression layer is located between the piezoelectric layer and the substrate, even if the thickness of the transverse mode suppression layer and the curvature of the fast transverse wave slow curve meet the requirements, the surface acoustic wave resonator still has transverse modes. Figure 13 The horizontal shear wave slowness curve of the surface acoustic wave resonator when the lateral mode suppression layer is located between the piezoelectric layer and the substrate, as provided in the embodiments of the present invention, is shown below. Figure 13 As shown, taking γ1=1 and h=10nm as an example, in S y The curve at point A5 is convex, meaning the curvature of the slowness curve of the surface acoustic wave (SAW) resonator at point A5 is greater than 0, indicating the presence of a transverse mode. It should be noted that the SAW resonator still exhibits a transverse mode even when the transverse mode suppression layer is located on the lower surface of the substrate or only on the upper surface of the electrode layer.

[0080] The technical solution provided by this invention provides a transverse mode suppression layer, which includes at least a first transverse mode suppression layer located between the piezoelectric layer and the electrode layer. Furthermore, the wavelength λ and the thickness h of the transverse mode suppression layer satisfy 0.0025λ≤h≤0.03λ. This ensures a suitable thickness for the transverse mode suppression layer, thereby suppressing transverse modes and improving the performance of the surface acoustic wave resonator.

[0081] Optional, continue to refer to Figure 6 The orthographic projection of the first transverse mode suppression layer 401 onto the plane of the substrate 10 covers the orthographic projection of the piezoelectric layer 20 onto the plane of the substrate 10.

[0082] Specifically, the first lateral mode suppression layer 401 is located between the piezoelectric layer 20 and the electrode layer 30, with its upper surface in direct contact with the electrode layer 30 and its lower surface in direct contact with the piezoelectric layer 20. The first lateral mode suppression layer 401 can completely cover the piezoelectric layer 20, thus achieving suppression of lateral modes while also simplifying the fabrication process.

[0083] Optional, Figure 14 for Figure 5 The corresponding schematic diagram of the fourth cross-sectional structure of the surface acoustic wave resonator along section line B-B' is shown below. Figure 14 As shown, the first transverse mode suppression layer 401 includes a first groove 4011, which extends along the thickness direction of the surface acoustic wave resonator (e.g., ...). Figure 14 (As shown in the Z direction), the first groove 4011 penetrates a portion of the first transverse mode suppression layer 401, and a portion of the electrode layer 30 is located within the opening 4011.

[0084] Specifically, a first groove 4011 is formed in the first transverse mode suppression layer 401 along the thickness direction Z of the surface acoustic wave resonator. The first groove 4011 penetrates a portion of the first transverse mode suppression layer 401, meaning the depth of the first groove 4011 is less than the thickness of the electrode layer 30. A portion of the electrode layer 30 is located within the opening 4011, meaning the interdigitated electrode 301 includes a portion located within the first groove 4011 and a portion located outside the first groove 4011. Specifically, the upper surface of the interdigitated electrode 301 is located on the side of the upper surface of the first transverse mode suppression layer 401 away from the substrate 10. This suppresses transverse modes, improving the resonator's performance, and also allows for diverse resonator configurations.

[0085] Optional, Figure 15 for Figure 5 The corresponding schematic diagram of the fourth cross-sectional structure of the surface acoustic wave resonator along section line B-B' is shown below. Figure 15 As shown, the first transverse mode suppression layer 401 includes a connecting portion 4012 and a plurality of protrusions 4013; along the thickness direction Z of the surface acoustic wave resonator, the protrusions 4013 are located on the side of the connecting portion 4012 away from the substrate 10; the plurality of protrusions 4013 are arranged along the first direction and are all connected to the connecting portion 4012; the electrode layer 30 is located on the side of the protrusions 4013 away from the substrate 10.

[0086] Specifically, multiple protrusions 4013 are located on the upper surface of the connecting portion 4012 and are connected to the connecting portion 4012, meaning that the protrusions 4013 and the connecting portion 4012 are integrated.

[0087] Specifically, the electrode layer 30 is located on the side of the protrusion 4013 away from the substrate 10. That is, the electrode layer 30 is located on the upper surface of the protrusion 4013. This can suppress transverse modes and improve the performance of the resonator, and also enable the resonator to be configured in a variety of ways.

[0088] For example, the orthographic projection of the electrode layer 30 onto the plane of the substrate 10 can coincide with the orthographic projection of the protrusion 4013 onto the plane of the substrate 10.

[0089] Optional, Figure 16 for Figure 5 The corresponding schematic diagram of the fourth cross-sectional structure of the surface acoustic wave resonator along section line B-B'. Figure 17 for Figure 5 The corresponding fifth cross-sectional structure of the surface acoustic wave resonator along section line B-B' is shown in the diagram. Figure 16 and Figure 17 As shown, the orthographic projection of the first lateral mode suppression layer 401 onto the plane of the substrate 10 covers the orthographic projection of the interdigitated electrode 301 onto the plane of the substrate 10.

[0090] As one possible implementation method, please refer to [reference]. Figure 16 The first lateral mode suppression layer 401 is not a single layer structure, but is broken at the gap between two adjacent interdigital electrodes 301. That is, the orthogonal projection of the first lateral mode suppression layer 401 on the substrate 10 covers the interdigital electrodes 301 and part of the gap between two adjacent interdigital electrodes 301, which is beneficial to realize the diversified configuration of the first lateral mode suppression layer 401.

[0091] As another feasible implementation method, please refer to Figure 17 The orthographic projection of the first lateral mode suppression layer 401 onto the plane of the substrate 10 coincides with the orthographic projection of the interdigitated electrode 301 onto the plane of the substrate 10. Thus, on the one hand, the fabrication process of the first lateral mode suppression layer 401 is simple, and on the other hand, it can realize diverse settings of the first lateral mode suppression layer 401.

[0092] Optional, Figure 18 for Figure 5 The corresponding schematic diagram of the sixth cross-sectional structure of the surface acoustic wave resonator along section line B-B' is shown below. Figure 18As shown, the first lateral mode suppression layer 401 includes a first surface a1 and a second surface a2; along the thickness direction of the surface acoustic wave resonator, the first surface a1 is located on the side of the second surface a2 away from the substrate 10; the piezoelectric layer 20 includes a second groove 201, and along the thickness direction Z of the surface acoustic wave resonator, the second groove 201 penetrates a portion of the piezoelectric layer 20; the piezoelectric layer 201 also includes a third surface a3 and a fourth surface a4; along the thickness direction Z of the surface acoustic wave resonator, the third surface a3 is located on the side of the fourth surface a4 away from the substrate 10; the first lateral mode suppression layer 401 is located in the second groove 201, and along the thickness direction Z of the surface acoustic wave resonator, the first surface a1 and the third surface a3 are flush.

[0093] Specifically, the first transverse mode suppression layer 401 includes a first surface a1 and a second surface a2. The first surface a1 can be understood as the upper surface of the first transverse mode suppression layer 401, and the second surface a2 can be understood as the lower surface of the first transverse mode suppression layer 401.

[0094] Specifically, the piezoelectric layer 20 includes a second groove 201, which extends through a portion of the piezoelectric layer 20 along the thickness direction Z of the surface acoustic wave resonator, allowing the first lateral mode suppression layer 401 to be fabricated within the second groove 201. The piezoelectric layer 201 also includes a third surface a3 and a fourth surface a4. The third surface a3 can be understood as the upper surface of the piezoelectric layer 20, and the fourth surface a4 can be understood as the lower surface of the piezoelectric layer 20.

[0095] Specifically, the first transverse mode suppression layer 401 is located in the second groove 201, and along the thickness direction Z of the surface acoustic wave resonator, the first surface a1 and the third surface a3 are flush, that is, the upper surface of the first transverse mode suppression layer 401 and the upper surface of the piezoelectric layer 20 are on the same horizontal line, thus enabling the diversity of the setting of the first transverse mode suppression layer 401.

[0096] For example, Figure 18 Only the technical solution shown is that the orthographic projection of the first lateral mode suppression layer 401 on the plane of the substrate 10 coincides with the orthographic projection of the interdigitated electrode 301 on the plane of the substrate 10. Figure 19 for Figure 5 The corresponding schematic diagram of the seventh cross-sectional structure of the surface acoustic wave resonator along section line B-B' is shown below. Figure 19 As shown, along the first direction X, the width of the first lateral mode suppression layer 401 is greater than the width of the interdigital electrode 301, that is, the orthogonal projection area of ​​the first lateral mode suppression layer 401 on the plane where the substrate 10 is located is greater than the orthogonal projection area of ​​the interdigital electrode 301 on the plane where the substrate 10 is located. This is beneficial for realizing the diversified arrangement of the lateral mode suppression layer 401.

[0097] Optional, Figure 20 forFigure 5 The corresponding schematic diagram of the sixth cross-sectional structure of the surface acoustic wave resonator along section line B-B' is shown below. Figure 20 As shown, the electrode layer 30 includes at least two electrode sublayers 30-1; the at least two electrode sublayers 30-1 include a first electrode sublayer 30-11 and a second electrode sublayer 30-12; the first electrode sublayer 30-11 is located on the side of the second electrode sublayer 30-12 away from the substrate 10; the lateral mode suppression layer 40 also includes a second lateral mode suppression layer 402 located between the first electrode sublayer 30-11 and the second electrode sublayer 30-12.

[0098] Specifically, electrode layer 30 includes at least two electrode sublayers 30-1, meaning electrode layer 30 can include multiple electrode sublayers 30-1. The at least two electrode sublayers 30-1 include a first electrode sublayer 30-11 and a second electrode sublayer 30-12, with the first electrode sublayer 30-11 located above the second electrode sublayer 30-12. Lateral mode suppression layer 40 also includes a second lateral mode suppression layer 402 located between the first electrode sublayer 30-11 and the second electrode sublayer 30-12, meaning the lateral mode suppression layer 40 is located between two adjacent electrode sublayers 30-1, forming a sandwich structure of "second electrode sublayer 30-12 - second lateral mode suppression layer 402 - first electrode sublayer 30-11". The film layers above the piezoelectric layer 20 can be sequentially arranged as "first transverse mode suppression layer 401 - second electrode sublayer 30-12 - second transverse mode suppression layer 402 - first electrode sublayer 30-11" or "first transverse mode suppression layer 401 - second electrode sublayer 30-12 - second transverse mode suppression layer 402 - first electrode sublayer 30-11 - second transverse mode suppression layer 402", which facilitates the diversified arrangement of transverse mode suppression layers.

[0099] It should be noted that the sum of the thicknesses of the first transverse mode suppression layer 401 and the second transverse mode suppression layer 402 is the total thickness h of the transverse mode suppression layer 40.

[0100] Optional, continue to refer to Figure 6 The material of the piezoelectric layer 20 includes lithium tantalate.

[0101] Specifically, the piezoelectric layer 20 is made of lithium tantalate. Since lithium tantalate has good temperature stability and electromechanical coupling performance, it is beneficial to improve the performance of surface acoustic wave resonators.

[0102] Optionally, the surface acoustic wave (SAW) resonator also includes reflectors located on the left and right sides of the interdigital transducer. These reflectors reflect leaked SAW waves back to the effective aperture region, thereby reducing SAW leakage and improving the Q value. Understandably, the reflectors include multiple reflective gratings arranged along a first direction and busbars electrically connected to the reflective gratings.

[0103] Based on the same inventive concept, this invention also provides a filter. Figure 21 A schematic diagram of a filter structure provided in an embodiment of the present invention is shown below. Figure 21 As shown, the filter 1000 includes at least one series arm resonator 1001 and at least one parallel arm resonator 1002; at least one of the series arm resonator 1001 and the parallel arm resonator 1002 includes the surface acoustic wave resonator 100 described in the above embodiments. Therefore, the filter provided by the embodiments of the present invention also has the above-mentioned beneficial effects, which will not be repeated here.

[0104] Specifically, the series arm resonator 1001 is connected in series between the input terminal 1003 and the output terminal 1004, and one end of the parallel arm resonator 1002 is connected between the input terminal 1003 and the output terminal 1004, while the other end is grounded.

[0105] Based on the same inventive concept, embodiments of the present invention also provide a multiplexer. Figure 22 This is a schematic diagram of the structure of a multiplexer provided in an embodiment of the present invention, such as... Figure 22 As shown, the multiplexer 10000 includes an antenna terminal ANT, at least one receiving unit 10001, and at least one transmitting unit 10002; the antenna terminal ANT is communicatively connected to the receiving unit 10001 and the transmitting unit 10002 respectively; at least one of the receiving unit 10001 and the transmitting unit 10002 includes the filter 1000 described in the above embodiments, so the multiplexer also has the above-mentioned beneficial effects, which will not be repeated here.

[0106] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A surface acoustic wave resonator, characterized by, include: substrate; A piezoelectric layer is located on one side of the substrate; Electrode layer; Located on the side of the piezoelectric layer away from the substrate; the electrode layer includes a plurality of interdigitated electrodes; the plurality of interdigitated electrodes include a plurality of first interdigitated electrodes and a plurality of second interdigitated electrodes; the first interdigitated electrodes and the second interdigitated electrodes are alternately arranged along a first direction and both extend along a second direction; the first direction intersects the second direction; A lateral mode suppression layer; the lateral mode suppression layer includes at least a first lateral mode suppression layer located between the piezoelectric layer and the electrode layer; Along the first direction, the dimension between any two adjacent first interdigital electrodes is the same as the dimension between any two adjacent second interdigital electrodes, and both are λ; the thickness of the lateral mode suppression layer is h; Where 0.0025λ≤h≤0.03λ.

2. The surface acoustic wave resonator according to claim 1, characterized by, The orthographic projection of the first lateral mode suppression layer onto the plane of the substrate covers the orthographic projection of the piezoelectric layer onto the plane of the substrate.

3. The surface acoustic wave resonator according to claim 2, wherein The first transverse mode suppression layer includes a first groove; Along the thickness direction of the surface acoustic wave resonator, the first groove penetrates a portion of the first transverse mode suppression layer; Part of the piezoelectric layer is located within the first groove.

4. The surface acoustic wave resonator according to claim 2, wherein The first transverse mode suppression layer includes a connecting portion and a plurality of protrusions; Along the thickness direction of the surface acoustic wave resonator, the protrusion is located on the side of the connection portion away from the substrate; a plurality of the protrusions are arranged along the first direction and are all connected to the connection portion; The electrode layer is located on the side of the protrusion away from the substrate.

5. The SAW resonator of claim 1, wherein, The orthographic projection of the first lateral mode suppression layer onto the plane of the substrate covers the orthographic projection of the interdigitated electrode onto the plane of the substrate.

6. The surface acoustic wave resonator according to claim 5, wherein The orthographic projection of the first lateral mode suppression layer onto the plane of the substrate coincides with the orthographic projection of the interdigitated electrode onto the plane of the substrate.

7. The surface acoustic wave resonator according to claim 5, wherein The first transverse mode suppression layer includes a first surface and a second surface; along the thickness direction of the surface acoustic wave resonator, the first surface is located on the side of the second surface away from the substrate; The piezoelectric layer includes a second groove, and the second groove penetrates a portion of the piezoelectric layer along the thickness direction of the surface acoustic wave resonator; the piezoelectric layer also includes a third surface and a fourth surface; along the thickness direction of the surface acoustic wave resonator, the third surface is located on the side of the fourth surface away from the substrate; The first transverse mode suppression layer is located within the second groove, and along the thickness direction of the surface acoustic wave resonator, the first surface and the third surface are flush.

8. The surface acoustic wave resonator of claim 1, wherein, The electrode layer includes at least two electrode sublayers; At least two electrode sublayers include a first electrode sublayer and a second electrode sublayer; the first electrode sublayer is located on the side of the second electrode sublayer away from the substrate; The transverse mode suppression layer further includes a second transverse mode suppression layer located between the first electrode sublayer and the second electrode sublayer.

9. The surface acoustic wave resonator of claim 1, wherein, The curvature of the fast transverse wave slow curve of the transverse mode suppression layer is γ1, where 0≤γ1≤1.

10. A filter, characterized by, It includes at least one series arm resonator and at least one parallel arm resonator; At least one of the series arm resonator and the parallel arm resonator includes the surface acoustic wave resonator of any one of claims 1-9.

11. A multiplexer, characterized by The filter includes an antenna terminal, at least one receiving unit, and at least one transmitting unit. The antenna terminal is communicatively connected to the receiving unit and the transmitting unit, respectively. At least one of the receiving unit and the transmitting unit includes the filter of claim 10.

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