Resonant devices and filters

Abstract

The embodiment of the present invention discloses a resonant device and a filter. The resonant device includes a wafer substrate, a piezoelectric layer and an interdigital electrode layer; the piezoelectric layer includes a piezoelectric single crystal material; the main positioning edge of the wafer substrate is located in the first direction, and the piezoelectric single crystal material includes a first crystal axis, a second crystal axis and a third crystal axis; the first crystal axis is perpendicular to the wafer substrate, or the first crystal axis is parallel to the wafer substrate and the angle between the first crystal axis and the first direction is less than or equal to 30 degrees, or greater than or equal to 60 degrees and less than or equal to 120 degrees; the second crystal axis is parallel to the wafer substrate and the angle between the second crystal axis and the first direction is less than or equal to 60 degrees, or the angle between the second crystal axis and the direction perpendicular to the wafer substrate is greater than or equal to 120 degrees and less than or equal to 135 degrees. The technical solution of the present invention is conducive to improving the performance and operating frequency of the resonant device while ensuring the low-cost advantage of the resonant device, and improving the performance of the bandpass filter containing the resonant device to meet the requirements of the 5G communication standard.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of wireless communication technology, and in particular to a resonant device and a filter. Background Art

[0002] As an important part of the wireless communication front end, RF filter devices have the functions of frequency selection and interference signal suppression. RF filter devices with better performance can not only improve the sensitivity of the transmitter and reduce the spectrum space occupied by the transmitter, but also improve the signal-to-noise ratio of the transceiver and reduce the power consumption of mobile devices in the communication link.

[0003] RF filter devices are composed of resonant devices, which usually include surface acoustic wave (SAW) resonant devices and bulk acoustic wave (BAW) resonant devices. SAW resonant devices and BAW resonant devices have technical and cost advantages in different frequency ranges. At present, in order to meet the needs of mobile broadband and high data rate wireless applications, modern communication standards are constantly developing towards higher frequencies and wider bandwidths. SAW resonant devices and BAW resonant devices in the existing technology can no longer meet the above standards.

[0004] For example, SAW resonant devices have the advantage of low cost, but the operating frequency of SAW resonant devices is low. If the operating frequency of SAW resonant devices is to be increased, the electrode width of the resonant device needs to be adjusted, so that the design of SAW resonant devices cannot take into account the power threshold, insertion loss and manufacturing cost of the device at the same time, which leads to SAW resonant devices with higher operating frequencies being either too expensive or insufficient in performance. Although BAW resonant devices have advantages in performance and high frequency, the manufacturing process of BAW resonant devices is complex, which increases the manufacturing cost of BAW resonant devices and makes it difficult to meet the needs of the consumer electronics market. Summary of the invention

[0005] The embodiments of the present invention provide a resonant device and a filter to improve the performance and operating frequency of the resonant device.

[0006] In a first aspect, an embodiment of the present invention provides a resonant device, including:

[0007] Wafer substrate;

[0008] A piezoelectric layer is located on one side of the wafer substrate, and the piezoelectric layer includes a piezoelectric single crystal material;

[0009] an interdigitated electrode layer, located on a side of the piezoelectric layer away from the substrate;

[0010] The main positioning edge of the wafer substrate is located in a first direction, and the piezoelectric single crystal material includes a first crystal axis, a second crystal axis and a third crystal axis that are perpendicular to each other; wherein, the first crystal axis is perpendicular to the wafer substrate, or the first crystal axis is parallel to the wafer substrate and the angle between the first crystal axis and the first direction is less than or equal to 30 degrees, or greater than or equal to 60 degrees and less than or equal to 120 degrees; the second crystal axis is parallel to the wafer substrate and the angle between the second crystal axis and the first direction is less than or equal to 60 degrees, or the angle between the second crystal axis and the direction perpendicular to the wafer substrate is greater than or equal to 120 degrees and less than or equal to 135 degrees.

[0011] Optionally, the first crystal axis is perpendicular to the wafer substrate, and along the clockwise direction, an angle between the first direction and the second crystal axis is greater than or equal to 0 degrees and less than or equal to 60 degrees.

[0012] Optionally, the first crystal axis is parallel to the wafer substrate, the angle between the second crystal axis and the direction perpendicular to the wafer substrate is greater than or equal to 120 degrees and less than or equal to 135 degrees, and along the clockwise direction, the angle between the first direction and the first crystal axis is greater than or equal to 60 degrees and less than or equal to 120 degrees.

[0013] Optionally, the first crystal axis is parallel to the wafer substrate, the angle between the second crystal axis and the direction perpendicular to the wafer substrate is greater than or equal to 30 degrees and less than or equal to 50 degrees, and along the clockwise direction, the angle between the first direction and the first crystal axis is greater than or equal to -30 degrees and less than or equal to 30 degrees, or greater than or equal to 60 degrees and less than or equal to 120 degrees.

[0014] Optionally, the interdigital electrode layer includes a plurality of first interdigital electrodes and a plurality of second interdigital electrodes;

[0015] The plurality of first interdigital electrodes are all connected to a bus bar located on a first side of the interdigital electrode layer, and the first interdigital electrodes are all extended from the first side of the interdigital electrode layer along a second direction to a second side of the interdigital electrode layer, and the second side is located on an opposite side to the first side;

[0016] The plurality of second interdigital electrodes are all connected to a bus bar located at a second side of the interdigital electrode layer, and the second interdigital electrodes are all extended from the second side to the first side along the second direction;

[0017] The vertical projections of the first interdigital electrodes and the second interdigital electrodes on the piezoelectric layer are alternate, and the first interdigital electrodes and the second interdigital electrodes are insulated from each other.

[0018] Optionally, an angle between the first direction and the third direction is greater than or equal to -30 degrees and less than or equal to 30 degrees, and the third direction is parallel to the wafer substrate and perpendicular to the second direction.

[0019] Optionally, the interdigital electrode layer further includes a plurality of first dummy interdigital electrodes and a plurality of second dummy interdigital electrodes;

[0020] The first dummy interdigital electrodes are located between adjacent first interdigital electrodes and connected to the bus bar on the first side, and the first dummy interdigital electrodes extend from the first side to the second side along the second direction;

[0021] The second dummy interdigital electrodes are located between adjacent second interdigital electrodes and connected to the bus bar on the second side, and the second dummy interdigital electrodes extend from the second side to the first side along the second direction;

[0022] The first dummy interdigital electrodes, the second dummy interdigital electrodes, the first interdigital electrodes, and the second interdigital electrodes are insulated from each other.

[0023] Optionally, it further comprises an acoustic reflection grating, the acoustic reflection grating is located on a side of the piezoelectric layer away from the wafer substrate, the acoustic reflection grating is arranged on both sides of the interdigital electrode layer along the second direction, and is insulated from the interdigital electrode layer;

[0024] Each of the acoustic reflection gratings comprises a plurality of metal strips extending along the second direction, wherein the width of the metal strips in the third direction is greater than 0.25 times the width of the first interdigital electrode and the second interdigital electrode in the third direction, and less than 10 times the width of the first interdigital electrode and the second interdigital electrode in the third direction; wherein the third direction is parallel to the wafer substrate and perpendicular to the second direction;

[0025] A distance between the interdigital electrode layer and the adjacent metal strip is greater than 0.2 times the width of the first interdigital electrode and the second interdigital electrode in the third direction, and less than 10 times the width of the first interdigital electrode and the second interdigital electrode in the third direction.

[0026] Optionally, a metal layer is further included, which is located on a side of the interdigitated electrode layer away from the wafer substrate, and covers at least a portion of the bus bar on the first side of the interdigitated electrode layer and at least a portion of the bus bar on the second side of the interdigitated electrode layer.

[0027] In a second aspect, an embodiment of the present invention further provides a filter, comprising the resonant device described in the first aspect.

[0028] The resonant device provided by an embodiment of the present invention includes a wafer substrate, a piezoelectric layer and an interdigitated electrode layer; the piezoelectric layer includes a piezoelectric single crystal material; the main positioning edge of the wafer substrate is located in a first direction, and the piezoelectric single crystal material includes a first crystal axis, a second crystal axis and a third crystal axis that are perpendicular to each other; the first crystal axis is perpendicular to the wafer substrate, or the first crystal axis is parallel to the wafer substrate and the angle between the first crystal axis and the first direction is less than or equal to 30 degrees, or greater than or equal to 60 degrees and less than or equal to 120 degrees; the second crystal axis is parallel to the wafer substrate and the angle between the second crystal axis and the first direction is less than or equal to 60 degrees, or the angle between the second crystal axis and the direction perpendicular to the wafer substrate is greater than or equal to 120 degrees and less than or equal to 135 degrees. The technical solution of the embodiment of the present invention realizes the excitation of longitudinally polarized surface acoustic waves through the resonant device. By setting the specific direction of the crystal axis, the specific direction of the piezoelectric single crystal material in the piezoelectric layer is set to adjust the internal geometry and structure of the resonant device. Since the piezoelectric single crystal material has the anisotropic characteristic, the piezoelectric single crystal material is bonded to the wafer substrate in the above-mentioned specific direction, which helps to enhance the piezoelectric effect generated by the piezoelectric layer, thereby improving the electromechanical coupling coefficient of the resonant device and enhancing the performance of the resonant device. The technical solution of the embodiment of the present invention alleviates the problem that the surface acoustic wave resonant device in the prior art cannot take into account both high performance and low cost, and is conducive to improving the performance and operating frequency of the resonant device while ensuring the low cost advantage of the resonant device, thereby improving the performance of the bandpass filter containing the resonant device to meet the requirements of the 5G communication standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of a resonant device provided by an embodiment of the present invention;

[0030] Figure 2 is a top view of a resonant device provided by an embodiment of the present invention;

[0031] Figure 3 is a cross-sectional view of a resonant device provided by an embodiment of the present invention;

[0032] Figure 4 is a schematic structural diagram of a piezoelectric single crystal material provided by an embodiment of the present invention;

[0033] Figure 5 is a cross-sectional view of another resonant device provided by an embodiment of the present invention;

[0034] Figure 6 is a cross-sectional view of another resonant device provided by an embodiment of the present invention;

[0035] Figure 7 is a schematic structural diagram of another resonant device provided by an embodiment of the present invention;

[0036] Figure 8is a cross-sectional view of another resonant device provided by an embodiment of the present invention;

[0037] Fig. 9 is a cross-sectional view of another resonant device provided by an embodiment of the present invention;

[0038] Fig.10 is a schematic structural diagram of another resonant device provided by an embodiment of the present invention;

[0039] Fig.11 is a schematic structural diagram of another resonant device provided by an embodiment of the present invention;

[0040] Fig.12 is a schematic structural diagram of another resonant device provided by an embodiment of the present invention;

[0041] Fig.13 is a top view of another resonant device provided by an embodiment of the present invention;

[0042] Fig.14 is a cross-sectional view of another resonant device provided by an embodiment of the present invention;

[0043] Fig.15 is a cross-sectional view of another resonant device provided by an embodiment of the present invention;

[0044] Fig.16 is a top view of another resonant device provided by an embodiment of the present invention;

[0045] Fig.17 is a cross-sectional view of another resonant device provided by an embodiment of the present invention;

[0046] Fig.18 is a schematic diagram of stress distribution of a resonant device provided in an embodiment of the present invention;

[0047] Fig.19 is a schematic diagram of displacement distribution of a resonant device provided by an embodiment of the present invention;

[0048] Fig. 20 is an admittance characteristic curve of the resonant device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0050] An embodiment of the present invention provides a resonant device, Figure 1is a schematic diagram of the structure of a resonant device provided by an embodiment of the present invention, specifically a side view of a wafer-level resonant device, wherein Figure 1 The wafer substrate 10 and the piezoelectric layer 20 of the wafer-level resonant device are only schematically shown. The wafer-level resonant device may include a plurality of resonant devices. Figure 1 A resonant device 100 is shown; Figure 2 is a top view of a resonant device provided by an embodiment of the present invention, which may be specifically Figure 1 A top view of the resonant device 100; Figure 3 is a cross-sectional view of a resonant device provided by an embodiment of the present invention, which may be specifically Figure 2 A cross-sectional view of the resonant device shown is obtained by cutting along the section line AA'; Figure 4 It is a schematic structural diagram of a piezoelectric single crystal material provided in an embodiment of the present invention.

[0051] Combination Figures 1 to 4 The resonant device 100 provided in an embodiment of the present invention includes: a wafer substrate 10, a piezoelectric layer 20 and an interdigital electrode layer 30; the piezoelectric layer 20 is located on one side of the wafer substrate 10, and the piezoelectric layer 20 includes a piezoelectric single crystal material; the interdigital electrode layer 30 is located on the side of the piezoelectric layer 20 away from the substrate; the main positioning edge 11 of the wafer substrate 10 is located in the first direction N1, and the piezoelectric single crystal material includes a first crystal axis X, a second crystal axis Y and a third crystal axis Z that are perpendicular to each other; wherein the first crystal axis X is perpendicular to the wafer substrate 10, or the first crystal axis X is parallel to the wafer substrate 10 and the angle between the first crystal axis X and the first direction N1 is less than or equal to 30 degrees, or greater than or equal to 60 degrees and less than or equal to 120 degrees; the second crystal axis Y is parallel to the wafer substrate 10 and the angle between the second crystal axis Y and the first direction N1 is less than or equal to 60 degrees, or the angle between the second crystal axis Y and the direction perpendicular to the wafer substrate 10 is greater than or equal to 120 degrees and less than or equal to 135 degrees.

[0052] Specifically, the wafer substrate 10 can provide buffering, protection or support for the resonant device, and the material of the wafer substrate 10 can be sapphire. The film layers in the resonant device can be formed on the wafer substrate 10 in sequence to form a wafer-level resonant device including a plurality of resonant devices. After the wafer-level resonant device is formed, the resonant device 100 can be obtained by cutting it. The piezoelectric layer 20 can be formed on the wafer substrate 10 by bonding. The piezoelectric layer 20 can be composed of a plurality of piezoelectric single crystal materials arranged according to a certain rule. The piezoelectric single crystal material refers to a single crystal material with a piezoelectric effect. Under the action of an electric field, mechanical stress will be generated in the piezoelectric single crystal material and corresponding deformation will occur.

[0053] The interdigital electrode layer 30 may include two groups of interdigital electrodes extending along the second direction N2, and the two groups of interdigital electrodes form a metal electrode pattern similar to the fingers of two hands interlaced on the piezoelectric layer 20. When the two groups of interdigital electrodes in the resonant device 100 input electrical signals to apply an electric field in a third direction N3 (the third direction N3 refers to a direction parallel to the wafer substrate 10 and perpendicular to the extension direction of the interdigital electrodes) to the piezoelectric layer 20, so that an electric field in the third direction N3 is generated in the entire thickness direction of the piezoelectric layer 20 (a direction perpendicular to the wafer substrate 10), the interdigital electrodes can excite surface acoustic waves propagating along the third direction N3 in the piezoelectric layer 20, that is, longitudinally polarized acoustic waves, and convert the surface acoustic waves into corresponding electrical signals for output to achieve filtering.

[0054] Since the crystal structure has three-dimensional periodicity in spatial arrangement, each type of crystal structure has a corresponding crystal axis coordinate system containing three crystal axes. Figure 4 The crystal structure of the trigonal piezoelectric single crystal material shown is used as an example for schematic illustration, but does not limit the type of crystal structure of the piezoelectric single crystal material. Figure 4 The piezoelectric single crystal material shown can be any one of lithium niobate and lithium tantalate. In the crystal structure of the piezoelectric single crystal material, the third crystal axis Z can be located on the longer body diagonal of the crystal, and the midpoint of the body diagonal can be the origin of the coordinates. A plane perpendicular to the third crystal axis Z can be obtained to obtain the plane where the first crystal axis X and the second crystal axis Y are located. When the crystal axis direction of the piezoelectric single crystal material in the piezoelectric layer 20 is determined, the setting direction of the piezoelectric single crystal material relative to the wafer substrate 10 and the interdigital electrode layer 30 is also determined.

[0055] Figure 1 The schematic diagram shows a situation where the first crystal axis X is perpendicular to the wafer substrate 10, that is, the plane formed by the second crystal axis Y and the third crystal axis Z is parallel to the wafer substrate 10, and the angle a1 between the second crystal axis Y and the main positioning edge 11 of the wafer substrate 10 is less than or equal to 60 degrees. The first direction N1 where the main positioning edge 11 of the wafer substrate 10 is located can also be the device direction. Since the piezoelectric single crystal material has the anisotropic characteristic, in this embodiment, the first crystal axis X is set to be perpendicular to the wafer substrate 10, the plane formed by the second crystal axis Y and the third crystal axis Z is parallel to the wafer substrate 10, and the angle a1 between the second crystal axis Y and the main positioning edge 11 of the wafer substrate 10 is less than or equal to 60 degrees, so that when the resonant device applies an electric field to the piezoelectric single crystal material through the interdigitated electrodes, the piezoelectric effect generated by the piezoelectric layer can be enhanced, thereby improving the electromechanical coupling coefficient of the resonant device, so as to enhance the performance of the resonant device and increase the operating frequency of the resonant device.

[0056] In other embodiments of the present invention, the first crystal axis X may also be parallel to the wafer substrate 10, and the angle between the first crystal axis X and the main positioning edge 11 of the wafer substrate 10 may be less than or equal to 30 degrees, or greater than or equal to 60 degrees and less than or equal to 120 degrees. The second crystal axis Y may also be parallel to the wafer substrate 10, and the angle between the second crystal axis Y and the main positioning edge 11 of the wafer substrate 10 may be less than or equal to 60 degrees, or the angle between the second crystal axis Y and the direction perpendicular to the wafer substrate 10 is greater than or equal to 120 degrees and less than or equal to 135 degrees. This embodiment sets a specific direction of the piezoelectric single crystal material in the piezoelectric layer by setting a specific direction of the crystal axis. Since the piezoelectric single crystal material has anisotropic characteristics, bonding the piezoelectric layer to the wafer substrate in the above-mentioned specific direction also helps to enhance the piezoelectric effect generated by the piezoelectric layer, thereby improving the electromechanical coupling coefficient of the resonant device, so as to enhance the performance of the resonant device and increase the operating frequency of the resonant device.

[0057] The technical solution of the embodiment of the present invention realizes the excitation of longitudinally polarized surface acoustic waves through the resonant device. By setting the specific direction of the crystal axis, the specific direction of the piezoelectric single crystal material in the piezoelectric layer is set to adjust the internal geometry and structure of the resonant device. Since the piezoelectric single crystal material has the anisotropic characteristic, the piezoelectric single crystal material is bonded to the wafer substrate in the above-mentioned specific direction, which helps to enhance the piezoelectric effect generated by the piezoelectric layer, thereby improving the electromechanical coupling coefficient of the resonant device and enhancing the performance of the resonant device. The technical solution of the embodiment of the present invention alleviates the problem that the surface acoustic wave resonant device in the prior art cannot take into account both high performance and low cost, and is conducive to improving the performance and operating frequency of the resonant device while ensuring the low cost advantage of the resonant device, thereby improving the performance of the bandpass filter containing the resonant device to meet the requirements of the 5G communication standard.

[0058] Combination Figures 1 to 4 On the basis of the above embodiment, optionally, the first crystal axis X is set perpendicular to the wafer substrate 10, and along the clockwise direction, the angle a1 between the first direction N1 and the second crystal axis Y is greater than or equal to 0 degree and less than or equal to 60 degrees.

[0059] Exemplarily, the first crystal axis X is perpendicular to the wafer substrate 10, and the positive semi-axis of the first crystal axis X points to the direction in which the piezoelectric layer 20 is away from the wafer substrate 10, and the negative semi-axis (-X) of the first crystal axis X points to the direction in which the piezoelectric layer 20 is close to the wafer substrate 10, or the positive semi-axis of the first crystal axis X points to the direction in which the piezoelectric layer 20 is close to the wafer substrate 10, and the negative semi-axis of the first crystal axis X points to the direction in which the piezoelectric layer 20 is away from the wafer substrate 10. In the clockwise direction, the angle between the first direction N1 and the second crystal axis Y is greater than or equal to 0 degrees and less than or equal to 60 degrees, which means that the positive semi-axis or negative semi-axis (-Y) of the second crystal axis Y can be rotated clockwise from the positioning edge 11 of the wafer substrate 10 to any position between 0 degrees and 60 degrees. This embodiment sets a specific direction of the piezoelectric single crystal material in the piezoelectric layer by setting a specific direction of the crystal axis. Since the piezoelectric single crystal material has anisotropy, bonding the piezoelectric layer to the wafer substrate in the above-mentioned specific direction helps to enhance the piezoelectric effect generated by the piezoelectric layer, thereby improving the electromechanical coupling coefficient of the resonant device, thereby enhancing the performance of the resonant device and increasing the operating frequency of the resonant device. Experimental verification shows that the electromechanical coupling coefficient of the resonant device provided by this embodiment is as high as about 15%.

[0060] Figure 5 is a cross-sectional view of another resonant device provided by an embodiment of the present invention, which may be Figure 2 Another cross-sectional view of the resonant device shown is obtained by cutting along the section line AA', wherein Figure 5 Only the wafer substrate 10 and the piezoelectric layer 20 of the resonant device are shown; Figure 6 is a cross-sectional view of another resonant device provided by an embodiment of the present invention, which may be Figure 2 Another cross-sectional view of the resonant device shown is obtained by cutting along the section line AA', wherein Figure 6 Only the wafer substrate 10 and the piezoelectric layer 20 of the resonant device are shown; Figure 7 is a schematic diagram of the structure of another resonant device provided by an embodiment of the present invention, specifically a side view of another wafer-level resonant device, wherein Figure 7 Only the wafer substrate 10 and the piezoelectric layer 20 of the wafer-level resonator device are shown.

[0061] Combination Figures 4 to 7 Optionally, the first crystal axis X is set parallel to the wafer substrate 10, the angle a2 between the second crystal axis Y and the direction perpendicular to the wafer substrate 10 is greater than or equal to 120 degrees and less than or equal to 135 degrees, and along the clockwise direction, the angle a3 between the first direction N1 and the first crystal axis X is greater than or equal to 60 degrees and less than or equal to 120 degrees.

[0062] For example, along the clockwise direction, the angle between the first direction N1 and the first crystal axis X is greater than or equal to 60 degrees and less than or equal to 120 degrees, which means that the first crystal axis X can be located at any position between 60 degrees and 120 degrees when the positioning edge 11 of the wafer substrate 10 is rotated clockwise. The direction perpendicular to the wafer substrate 10 can be Figure 5 and Figure 6 In the direction of the dotted line L shown in the figure, the angle a2 between the second crystal axis Y and the direction perpendicular to the wafer substrate 10 is greater than or equal to 120 degrees and less than or equal to 135 degrees, which means that the second crystal axis Y can be located at any position between 120 degrees and 135 degrees rotated clockwise from the dotted line L, and the positive semi-axis of the second crystal axis Y points to the side of the piezoelectric layer 20 close to the wafer substrate 10 (such as Figure 5 ), or the positive half axis of the second crystal axis Y points to the side of the piezoelectric layer 20 away from the wafer substrate 10 (as shown in Figure 6 As shown). This embodiment sets a specific direction of the crystal axis to achieve a specific direction of the piezoelectric single crystal material in the piezoelectric layer. Since the piezoelectric single crystal material has anisotropy, bonding the piezoelectric layer to the wafer substrate in the above-mentioned specific direction helps to enhance the piezoelectric effect generated by the piezoelectric layer, thereby improving the electromechanical coupling coefficient of the resonant device, thereby enhancing the performance of the resonant device and increasing the operating frequency of the resonant device. It has been experimentally verified that the electromechanical coupling coefficient of the resonant device provided by this embodiment is as high as about 10%.

[0063] Figure 8 is a cross-sectional view of another resonant device provided by an embodiment of the present invention, which may be Figure 2 Another cross-sectional view of the resonant device shown is obtained by cutting along the section line AA', wherein Figure 8 Only the wafer substrate 10 and the piezoelectric layer 20 of the resonant device are shown; Fig. 9 is a cross-sectional view of another resonant device provided by an embodiment of the present invention, which may be Figure 2 Another cross-sectional view of the resonant device shown is obtained by cutting along the section line AA', wherein Fig. 9 Only the wafer substrate 10 and the piezoelectric layer 20 of the resonant device are shown; Fig.10 is a schematic diagram of the structure of another resonant device provided by an embodiment of the present invention, specifically a side view of another wafer-level resonant device, wherein Fig.10 Only the wafer substrate 10 and the piezoelectric layer 20 of the wafer-level resonator device are shown.

[0064] Combination Figure 4 as well as Figures 8 to 10Optionally, the first crystal axis X is set parallel to the wafer substrate 10, the angle a4 between the second crystal axis Y and the direction perpendicular to the wafer substrate 10 is greater than or equal to 30 degrees and less than or equal to 50 degrees, and along the clockwise direction, the angle a5 between the first direction N1 and the first crystal axis X is greater than or equal to -30 degrees and less than or equal to 30 degrees, or greater than or equal to 60 degrees and less than or equal to 120 degrees.

[0065] For example, along the clockwise direction, the angle a5 between the first direction N1 and the first crystal axis X is greater than or equal to -30 degrees and less than or equal to 30 degrees, or greater than or equal to 60 degrees and less than or equal to 120 degrees, which means that the first crystal axis X can be located at any position between -30 degrees and 120 degrees when the positioning edge 11 of the wafer substrate 10 is rotated clockwise, or located at any position between 60 degrees and 120 degrees when the positioning edge 11 of the wafer substrate 10 is rotated clockwise. The direction perpendicular to the wafer substrate 10 can be Figure 8 and Fig. 9 In the direction of the dotted line L shown in the figure, the angle a4 between the second crystal axis Y and the direction perpendicular to the wafer substrate 10 is greater than or equal to 30 degrees and less than or equal to 50 degrees, which means that the second crystal axis Y can be located at any position between 30 degrees and 50 degrees rotated clockwise from the dotted line L, and the positive semi-axis of the second crystal axis Y points to the side of the piezoelectric layer 20 away from the wafer substrate 10 (such as Figure 8 As shown), or the positive half axis of the second crystal axis Y points to the side of the piezoelectric layer 20 close to the wafer substrate 10 (as shown Fig. 9 As shown). This embodiment sets a specific direction of the crystal axis to achieve a specific direction of the piezoelectric single crystal material in the piezoelectric layer. Since the piezoelectric single crystal material has anisotropy, bonding the piezoelectric layer to the wafer substrate in the above-mentioned specific direction helps to enhance the piezoelectric effect generated by the piezoelectric layer, thereby improving the electromechanical coupling coefficient of the resonant device, thereby enhancing the performance of the resonant device and increasing the operating frequency of the resonant device. It has been experimentally verified that the electromechanical coupling coefficient of the resonant device provided by this embodiment is as high as about 10%.

[0066] See also Figure 2 and Figure 3Optionally, a forked finger electrode layer 30 is provided to include a plurality of first forked finger electrodes 310 and a plurality of second forked finger electrodes 320; the plurality of first forked finger electrodes 310 are all connected to a bus bar 311 located on a first side of the forked finger electrode layer 30, and the first forked finger electrodes 310 are all extended from the first side of the forked finger electrode layer 30 along a second direction N2 to a second side of the forked finger electrode layer 30, and the second side is located on the opposite side of the first side; the plurality of second forked finger electrodes 320 are all connected to a bus bar 321 located on a second side of the forked finger electrode layer 30, and the second forked finger electrodes 320 are all extended from the second side along a second direction N2 to the first side; the vertical projections of the first forked finger electrodes 310 and the second forked finger electrodes 320 on the piezoelectric layer 20 are alternating, and the first forked finger electrodes 310 and the second forked finger electrodes 320 are insulated from each other.

[0067] Specifically, the first interdigital electrodes 310 and the second interdigital electrodes 320 are both metal electrodes, and the materials of the first interdigital electrodes 310 and the second interdigital electrodes 320 may include any one of titanium (Ti), silver (Ag), aluminum (Al), copper (Cu), copper-aluminum alloy (AlCu), chromium (Cr), ruthenium (Ru), molybdenum (Moly) and tungsten (W), or the materials of the first interdigital electrodes 310 and the second interdigital electrodes 320 may also be a combination of the above materials. Each first interdigital electrode 310 is connected to a common electrode, i.e., a bus bar 311; each second interdigital electrode 320 is connected to a common electrode, i.e., a bus bar 321. The widths of the first interdigital electrodes 310 may be the same or different, and the widths of the second interdigital electrodes 320 may also be the same or different. When the resonant device is working, the first interdigitated electrode 310 inputs the power signal Vin through the bus bar 311, and the second interdigitated electrode 320 inputs the ground signal GND through the bus bar 321, so that the interdigitated electrode layer 30 can apply an electric field in the direction perpendicular to the first interdigitated electrode 310 and the second interdigitated electrode 320 in the piezoelectric layer 20, that is, the electric field in the third direction N3, so that the electric field in the third direction N3 is generated throughout the thickness direction of the piezoelectric layer 20, thereby exciting the surface acoustic wave propagating along the third direction N3, that is, the longitudinally polarized acoustic wave, and converting the surface acoustic wave into a corresponding electrical signal output to achieve filtering.

[0068] Fig.11 is a schematic diagram of the structure of another resonant device provided by an embodiment of the present invention, specifically a side view of another wafer-level resonant device, wherein Fig.11 Only the wafer substrate 10 and the piezoelectric layer 20 of the wafer-level resonant device are shown; Fig.12 is a schematic diagram of the structure of another resonant device provided by an embodiment of the present invention, specifically a side view of another wafer-level resonant device, wherein Fig.12 Only the wafer substrate 10 and the piezoelectric layer 20 of the wafer-level resonator device are shown. Figures 1 to 4 as well as Fig.11 and Fig.12 Optionally, an angle a1 between the first direction N1 and the third direction N3 is set to be greater than or equal to -30 degrees and less than or equal to 30 degrees, and the third direction N3 is parallel to the wafer substrate 10 and perpendicular to the second direction N2.

[0069] Exemplarily, the angle between the first direction N1 and the third direction N3 is greater than or equal to -30 degrees and less than or equal to 30 degrees, which means that the angle between the direction perpendicular to the extension direction of the first interdigital electrode 310 and the second interdigital electrode 320 (i.e., the second direction N2) (i.e., the third direction N3) and the main positioning edge 11 of the wafer substrate 10 is -30°≤a1≤30°. In other words, the angle between the propagation direction of the surface acoustic wave excited by the resonator device 100 (the third direction N3) and the main positioning edge 11 of the wafer substrate 10 is -30°≤a1≤30°. Wherein, Figure 1 The schematic diagram shows the situation where the angle a1 between the first direction N1 and the third direction N3 is 0°. Fig.11 The schematic diagram shows the situation where the angle a1 between the first direction N1 and the third direction N3 is 30°. Fig.12 The schematic diagram shows the situation where the angle a1=-30° between the first direction N1 and the third direction N3. Since the piezoelectric layer 20 generates mechanical stress and undergoes corresponding deformation under the action of the electric field applied by the interdigital electrodes, the surface acoustic wave propagating along the third direction N3 is excited in the piezoelectric layer 20. Considering that the piezoelectric single crystal material in the piezoelectric layer 20 has the characteristic of anisotropy, this embodiment adjusts the relative position relationship between the direction of the interdigital electrodes and the crystal structure orientation of the piezoelectric single crystal material by setting the angle between the first direction N1 and the third direction N3 to -30°≤a1≤30°, which is beneficial to enhance the piezoelectric effect generated by the piezoelectric layer while exciting the surface acoustic wave propagating along the third direction N3, thereby improving the electromechanical coupling coefficient of the resonant device, thereby enhancing the performance of the resonant device and increasing the operating frequency of the resonant device.

[0070] Fig.13 is a top view of another resonant device provided by an embodiment of the present invention, which may be Figure 1 Another top view of the resonant device 100 in FIG. Fig.13As shown, optionally, the interdigitated electrode layer 30 further includes a plurality of first dummy interdigitated electrodes 312 and a plurality of second dummy interdigitated electrodes 322; the first dummy interdigitated electrodes 312 are located between adjacent first interdigitated electrodes 310 and are connected to the bus bar 311 on the first side, and the first dummy interdigitated electrodes 312 extend from the first side along the second direction N2 to the second side; the second dummy interdigitated electrodes 322 are located between adjacent second interdigitated electrodes 320 and are connected to the bus bar 321 on the second side, and the second dummy interdigitated electrodes 322 extend from the second side along the second direction N2 to the first side; the first dummy interdigitated electrodes 312, the second dummy interdigitated electrodes 322, the first interdigitated electrodes 310 and the second interdigitated electrodes 320 are insulated from each other. The material of the first dummy interdigital electrode 312 and the second dummy interdigital electrode 322 can be the same as the material of the first dummy interdigital electrode 310 and the second dummy interdigital electrode 320. In this embodiment, by setting the first dummy interdigital electrode 312 and the second dummy interdigital electrode 322, a virtual short heel finger disconnected from the interdigital electrode is formed (for example, the first dummy interdigital electrode 312 forms a virtual short heel finger disconnected from the corresponding second interdigital electrode 320, and the second dummy interdigital electrode 322 forms a virtual short heel finger disconnected from the corresponding first interdigital electrode 310) so that the surface acoustic wave excited by the resonant device is reflected when it propagates to the first dummy interdigital electrode 312 and the second dummy interdigital electrode 322, thereby limiting the surface acoustic wave to the interior of the resonant device along the second direction N2, thereby improving the energy reflectivity of the resonant device and suppressing unnecessary stray responses.

[0071] Fig.14 is a cross-sectional view of another resonant device provided by an embodiment of the present invention, which may be Fig.13 The cross-sectional view of the resonant device shown is obtained by cutting along the section line bb'. Figure 2 , Fig.13 and Fig.14 Optionally, the resonant device 100 further includes an acoustic reflection grating 330, which is located on a side of the piezoelectric layer 20 away from the wafer substrate 10, and the acoustic reflection grating 330 is arranged on both sides of the interdigitated electrode layer 30 along the second direction N2 and is insulated from the interdigitated electrode layer 30; each acoustic reflection grating 330 includes a plurality of metal strips 331 extending along the second direction N2, and a width Wr of the metal strips 331 in the third direction N3 is greater than a width We of the first interdigitated electrode 310 and the second interdigitated electrode 320 in the third direction N3. 0.2 times, and less than 10 times the width We of the first interdigitated electrode 310 and the second interdigitated electrode 320 in the third direction N3; wherein the third direction N3 is parallel to the wafer substrate 10 and perpendicular to the second direction N2; the spacing Wg between the interdigitated electrode layer 30 and the adjacent metal strip 331 is greater than 0.2 times the width We of the first interdigitated electrode 310 and the second interdigitated electrode 320 in the third direction N3, and less than 10 times the width We of the first interdigitated electrode 310 and the second interdigitated electrode 320 in the third direction N3.

[0072] Specifically, the material of the acoustic reflection grating 330 may be the same as or different from the material of the first interdigital electrode 310 and the second interdigital electrode 320. The two ends of the metal strip 331 in the acoustic reflection grating 330 are respectively connected to the bus, that is, the bus 332 and the bus 333. The bus bar connecting the first interdigital electrode 310 and the second interdigital electrode 320 may be connected to the bus connected to the metal strip 331 in the acoustic reflection grating 330, or may not be connected. Figure 2 and Fig.13 Both show the situation that the busbars connecting the interdigital electrodes are not connected to the busbars connected to the metal strips in the acoustic reflection grid. In this embodiment, by arranging the acoustic reflection grid 330 on both sides of the interdigital electrode layer, it is possible to reduce the surface acoustic waves propagating to the outside of the acoustic reflection grid 330 on both sides of the resonant device based on the diffraction principle of acoustic waves, which helps to limit the surface acoustic waves to the inside of the resonant device along the third direction N3, thereby improving the energy conversion efficiency between the electrical energy and the mechanical energy of the resonant device.

[0073] The spacing Wg between the interdigital electrode layer 30 and the adjacent metal strip 331 refers to the spacing between the metal strip 331 closest to the interdigital electrode in the acoustic reflection grid and the first interdigital electrode 310 or the second interdigital electrode 320 closest to the acoustic reflection grid in the interdigital electrode layer. Fig.14 The schematic diagram shows the case where the widths of the first interdigitated electrode 310 and the second interdigitated electrode 320 in the third direction N3 are both We. In this embodiment, by setting the width of the metal strip 331 in the third direction N3 to 0.25We<Wr<10We, and the spacing between the interdigitated electrode layer 30 and the adjacent metal strip 331 to 0.2We<Wg<10We, it helps to weaken the diffraction of sound waves generated by the resonant device through the sound reflection grid, thereby further reducing the surface acoustic waves propagating from the resonant device to the outside of the sound reflection grid 330 on both sides, helping to confine the surface acoustic waves to the inside of the resonant device along the third direction N3, thereby improving the energy conversion efficiency between electrical energy and mechanical energy of the resonant device.

[0074] Fig.15 is a cross-sectional view of another resonant device provided by an embodiment of the present invention, which may be Fig.13 Another cross-sectional view of the resonant device shown is obtained by cutting along the section line bb'. Figure 3 , Fig.14 and Fig.15 As shown, optionally, the resonant device further includes a passivation layer 50 located on a side of the interdigital electrode layer 30 away from the wafer substrate 10 , and the passivation layer 50 covers the interdigital electrode layer 30 .

[0075] Specifically, the material of the passivation layer 50 can be silicon dioxide (SiO2) or silicon nitride (SiNx). In this embodiment, the passivation layer 50 is provided to cover the interdigital electrode layer 30 to isolate water and oxygen, thereby protecting the interdigital electrode layer 30. When the passivation layer 50 is formed on the side of the interdigital electrode layer 30 away from the wafer substrate 10, the upper surface of the passivation layer 50 away from the wafer substrate 10 can be formed into a plane, or the undulation of the upper surface of the passivation layer 50 can be consistent with the morphology of the upper surface of the interdigital electrode layer.

[0076] Fig.16 is a top view of another resonant device provided by an embodiment of the present invention, which may be Figure 1 Another top view of the resonant device 100; Fig.17 is a cross-sectional view of another resonant device provided by an embodiment of the present invention, which may be Fig.16 Another cross-sectional view of the resonant device shown is obtained by cutting along the section line CC'. Fig.16 and Fig.17 Optionally, the resonant device also includes a metal layer 60, which is located on a side of the interdigitated electrode layer 30 away from the wafer substrate 10, and the metal layer 60 covers at least a portion of the bus bar 311 on the first side of the interdigitated electrode layer 30, and covers at least a portion of the bus bar 321 on the second side of the interdigitated electrode layer 30.

[0077] Specifically, the material of the metal layer 60 may include any one of titanium (Ti), silver (Ag), aluminum (Al), copper (Cu), copper-aluminum alloy (AlCu), chromium (Cr), ruthenium (Ru), molybdenum (Moly) and tungsten (W), or a combination of the above materials. In this embodiment, by setting the metal layer 60 to cover at least a portion of the bus bar 311 and at least a portion of the bus bar 321, it is helpful to make the surface acoustic wave excited by the resonant device reflect when it propagates to the metal layer 60, so as to limit the surface acoustic wave to the inside of the resonant device along the second direction N2. At the same time, the metal layer 60 can also be exposed on the surface of the packaged resonant device 100, so that the interdigital electrodes can access the electrical signal through the metal layer and the bus bar covered by it.

[0078] On the basis of the above embodiments, optionally, one or more dielectric layers may be provided between the piezoelectric layer and the wafer substrate to adjust the electromechanical coupling coefficient of the resonant device, thereby improving the performance of the resonant device.

[0079] Combination Fig.13 and Fig.14On the basis of the above embodiments, optionally, the width of the first interdigitated electrode 310 and the second interdigitated electrode 320 in the third direction N3 is set to 250nm<We<1μm, so as to adjust the electromechanical coupling coefficient of the resonant device by adjusting the width of the interdigitated electrodes, thereby enhancing the performance of the resonant device and increasing the operating frequency of the resonant device.

[0080] Combination Fig.13 and Fig.14 Optionally, the total number of the first interdigital electrodes 310 and the second interdigital electrodes 320 is set to be greater than 50, so as to adjust the electromechanical coupling coefficient of the resonant device by adjusting the number of interdigital electrodes, thereby enhancing the performance of the resonant device and increasing the operating frequency of the resonant device. Optionally, the total number of the metal strips 331 in the acoustic reflection grid 330 is set to be greater than 50, so as to reduce the surface acoustic waves propagating from the resonant device to the outside of the acoustic reflection grid 330 on both sides, which helps to limit the surface acoustic waves to the inside of the resonant device along the third direction N3, thereby improving the energy conversion efficiency between electrical energy and mechanical energy of the resonant device.

[0081] Combination Fig.13 and Fig.14 Optionally, the overlapping length of the first interdigitated electrode 310 and the second interdigitated electrode 320 along the second direction N2 is set to 15μm<La<200μm, and the distance between the second interdigitated electrode 320 and the bus bar 311 (that is, the distance between the first interdigitated electrode 310 and the bus bar 321) is set to 250μm<Lg<5μm, so as to adjust the electromechanical coupling coefficient of the resonant device, thereby enhancing the performance of the resonant device and increasing the operating frequency of the resonant device.

[0082] Combination Fig.13 and Fig.14 , Optionally, the spacing between the adjacent first interdigital electrodes 310 and the second interdigital electrodes 320 in the interdigital electrodes 30 is set to 500nm<Wpi<2μm, and the spacing between the adjacent first interdigital electrodes 310 and the second interdigital electrodes 320 can be specifically the distance between the center of the first interdigital electrode 310 along the third direction N3 and the center of the adjacent second interdigital electrode 320 along the third direction N3. Since f=v / (2*Wpi), where f is the operating frequency of the resonant device, and v is the wave velocity of the surface acoustic wave propagation in the resonant device, therefore, when the wave velocity remains unchanged, the smaller the spacing Wpi between the first interdigital electrode 310 and the second interdigital electrode 320, the higher the operating frequency of the resonant device. In this embodiment, the spacing between the first interdigital electrode 310 and the second interdigital electrode 320 is set to increase the operating frequency of the resonant device.

[0083] Combination Fig.13 and Fig.14Optionally, the thickness of the first interdigitated electrode 310 and the second interdigitated electrode 320 in the direction perpendicular to the wafer substrate 10 is 500nm<Te<200nm, the thickness of the passivation layer 50 between the surface of the piezoelectric layer 20 away from the wafer substrate 10 and the surface of the passivation layer 50 close to the piezoelectric layer 20 is 100nm<Tp1<600nm, and the thickness of the piezoelectric layer 20 in the direction perpendicular to the wafer substrate 10 is 300nm<Tp2<1μm, so as to adjust the electromechanical coupling coefficient of the resonant device by adjusting the thickness of the interdigitated electrode, the thickness of the passivation layer and the thickness of the piezoelectric layer, thereby enhancing the performance of the resonant device and increasing the operating frequency of the resonant device.

[0084] Fig.18 is a schematic diagram of stress distribution of a resonant device provided in an embodiment of the present invention, Fig.18 It schematically shows that under the action of electric field, Fig.14 The stress distribution of each film layer of the resonant device is shown. Fig.14 and Fig.18 , under the action of the electric field, the mechanical stress generated by the resonant device mainly exists in the piezoelectric layer 20, the interdigital electrode layer and the passivation layer 50, and only a small amount of stress exists in the wafer substrate 10. And because the first interdigital electrode 310 inputs the power signal Vin, and the second interdigital electrode 320 inputs the ground signal GND, the second interdigital electrode 320 can respectively generate reverse electric fields E1 and E2 with the first interdigital electrodes 310 on both sides in the entire thickness direction of the piezoelectric layer 20, and accordingly, the stress generated by the resonant device in the piezoelectric layer 20 reaches an extreme value, for example, the electric field E1 applied by the second interdigital electrode 320 and the first interdigital electrode 310 on the left side in the piezoelectric layer 20 makes the stress generated at the corresponding position of the piezoelectric layer 20 reach a maximum value (close to Max), and the electric field E2 applied by the second interdigital electrode 320 and the first interdigital electrode 310 on the right side in the piezoelectric layer 20 makes the stress generated at the corresponding position of the piezoelectric layer 20 reach a minimum value (close to -Max).

[0085] Fig.19 is a schematic diagram of displacement distribution of a resonant device provided in an embodiment of the present invention, Fig.19 It schematically shows that under the action of electric field, Fig.14 The displacement distribution of each membrane layer of the resonant device is shown. Fig.14 and Fig.19 The displacement caused by the standing wave generated during the propagation of the acoustic wave in the resonant device is mainly in the piezoelectric layer 20 , the interdigital electrode layer and the passivation layer 50 , and there is only a small amount of displacement in the wafer substrate 10 .

[0086] Fig. 20 is the admittance characteristic curve of the resonant device provided by the embodiment of the present invention, which may be specifically Fig.13 and Fig.14The admittance characteristic curve obtained by simulation experiment of the resonant device shown in the figure. Fig. 20 As shown, the resonant frequency of the resonant device provided in the embodiment of the present invention is 2.62 GHz, and the electromechanical coupling coefficient K t 2 It can reach 12%. It can be seen that the scheme of this embodiment is helpful to improve the electromechanical coupling coefficient and frequency of the resonant device, and is helpful to determine the preferred structure and size of the resonant device according to the thickness, width of each film layer of the resonant device corresponding to the scheme, the size and position of the forked electrodes, and the size and position of the acoustic reflection grid relative to the forked electrodes.

[0087] The embodiment of the present invention further provides a filter, which includes the resonant device in any of the above embodiments of the present invention. The filter provided by the embodiment of the present invention includes the resonant device provided by any of the above embodiments of the present invention, and thus has the corresponding functional modules and beneficial effects of the resonant device, which will not be described in detail.

[0088] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A resonant device, characterized in that: include: Wafer substrate; A piezoelectric layer is located on one side of the wafer substrate, and the piezoelectric layer includes a piezoelectric single crystal material; an interdigitated electrode layer, located on a side of the piezoelectric layer away from the substrate; The main positioning edge of the wafer substrate is located in a first direction, and the piezoelectric single crystal material includes a first crystal axis, a second crystal axis and a third crystal axis that are perpendicular to each other; wherein the first crystal axis is perpendicular to the wafer substrate, or the first crystal axis is parallel to the wafer substrate and the angle between the first crystal axis and the first direction is less than or equal to 30 degrees, or greater than or equal to 60 degrees and less than or equal to 120 degrees; the second crystal axis is parallel to the wafer substrate and the angle between the second crystal axis and the first direction is less than or equal to 60 degrees, or the angle between the second crystal axis and the direction perpendicular to the wafer substrate is greater than or equal to 120 degrees and less than or equal to 135 degrees; The first crystal axis is perpendicular to the wafer substrate, and along the clockwise direction, an angle between the first direction and the second crystal axis is greater than or equal to 0 degrees and less than or equal to 60 degrees; The interdigital electrode layer includes a plurality of first interdigital electrodes and a plurality of second interdigital electrodes; The plurality of first interdigital electrodes are all connected to a bus bar located on a first side of the interdigital electrode layer, and the first interdigital electrodes are all extended from the first side of the interdigital electrode layer along a second direction to a second side of the interdigital electrode layer, and the second side is located on an opposite side to the first side; The plurality of second interdigital electrodes are all connected to a bus bar located at a second side of the interdigital electrode layer, and the second interdigital electrodes are all extended from the second side to the first side along the second direction; The vertical projections of the first interdigital electrodes and the second interdigital electrodes on the piezoelectric layer are alternate, and the first interdigital electrodes and the second interdigital electrodes are insulated from each other.

2. The resonant device according to claim 1, characterized in that: The first crystal axis is parallel to the wafer substrate, the angle between the second crystal axis and the direction perpendicular to the wafer substrate is greater than or equal to 120 degrees and less than or equal to 135 degrees, and along the clockwise direction, the angle between the first direction and the first crystal axis is greater than or equal to 60 degrees and less than or equal to 120 degrees.

3. The resonant device according to claim 1, characterized in that: The first crystal axis is parallel to the wafer substrate, the angle between the second crystal axis and the direction perpendicular to the wafer substrate is greater than or equal to 30 degrees and less than or equal to 50 degrees, and along the clockwise direction, the angle between the first direction and the first crystal axis is greater than or equal to -30 degrees and less than or equal to 30 degrees, or greater than or equal to 60 degrees and less than or equal to 120 degrees.

4. The resonant device according to claim 1, characterized in that: An angle between the first direction and the third direction is greater than or equal to -30 degrees and less than or equal to 30 degrees. The third direction is parallel to the wafer substrate and perpendicular to the second direction.

5. The resonant device according to claim 1, characterized in that: The interdigital electrode layer further includes a plurality of first dummy interdigital electrodes and a plurality of second dummy interdigital electrodes; The first dummy interdigital electrodes are located between adjacent first interdigital electrodes and connected to the bus bar on the first side, and the first dummy interdigital electrodes extend from the first side to the second side along the second direction; The second dummy interdigital electrodes are located between adjacent second interdigital electrodes and connected to the bus bar on the second side, and the second dummy interdigital electrodes extend from the second side to the first side along the second direction; The first dummy interdigital electrodes, the second dummy interdigital electrodes, the first interdigital electrodes, and the second interdigital electrodes are insulated from each other.

6. The resonant device according to claim 1, characterized in that: It also includes an acoustic reflection grating, the acoustic reflection grating is located on a side of the piezoelectric layer away from the wafer substrate, the acoustic reflection grating is arranged on both sides of the interdigital electrode layer along the second direction, and is insulated from the interdigital electrode layer; Each of the acoustic reflection gratings comprises a plurality of metal strips extending along the second direction, wherein the width of the metal strips in the third direction is greater than 0.25 times the width of the first interdigital electrode and the second interdigital electrode in the third direction, and less than 10 times the width of the first interdigital electrode and the second interdigital electrode in the third direction; wherein the third direction is parallel to the wafer substrate and perpendicular to the second direction; A distance between the interdigital electrode layer and the adjacent metal strip is greater than 0.2 times the width of the first interdigital electrode and the second interdigital electrode in the third direction, and less than 10 times the width of the first interdigital electrode and the second interdigital electrode in the third direction.

7. The resonant device according to claim 1, characterized in that: It also includes a metal layer, which is located on a side of the interdigitated electrode layer away from the wafer substrate, and covers at least a portion of the bus bar on the first side of the interdigitated electrode layer and at least a portion of the bus bar on the second side of the interdigitated electrode layer.

8. A filter, characterized in that: The resonant device comprises any one of claims 1 to 7.

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