A resonant device and an acoustic filter

Abstract

The embodiment of the present invention discloses a resonant device and an acoustic filter. The resonant device includes a wafer substrate, a piezoelectric layer and an interdigital electrode layer; the piezoelectric layer is located on one side of the wafer substrate, the piezoelectric layer includes a piezoelectric single crystal material, 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 direction of the electric field generated by the interdigital electrode layer in the piezoelectric layer is the device direction; wherein the first crystal axis is perpendicular to the wafer substrate, and the angle between the device direction and the second crystal axis is angle A1, ‑30°≤A1≤10°; or, the first crystal axis is perpendicular to the wafer substrate, and the angle between the device direction and the second crystal axis is angle A2, 170°≤A2≤210°; or, the angle between the second crystal axis and the direction perpendicular to the wafer substrate is angle B1, ‑20°≤B1≤40°, and the angle between the device direction and the first crystal axis is angle B2, ‑20°≤B2≤20°; while ensuring the low manufacturing cost of the resonant device, the operating frequency and performance of the resonant device are improved.

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 an acoustic filter. Background Art

[0002] As an important component of the wireless communication front end, RF acoustic filter devices have the functions of frequency selection and interference signal suppression. RF acoustic 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. RF acoustic filter devices are composed of resonant devices.

[0003] The existing resonant devices are mainly surface acoustic wave resonant devices (SAW) and bulk acoustic wave resonant devices (BAW). SAW resonant devices and BAW resonant devices each 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 an acoustic filter, so as to improve the operating frequency and performance of the resonant device while ensuring the low manufacturing cost of the resonant device.

[0006] In a first aspect, an embodiment of the present invention provides a resonant device, the resonant device comprising a wafer substrate, a piezoelectric layer, and an interdigital electrode layer;

[0007] The piezoelectric layer is located on one side of the wafer substrate, the piezoelectric layer includes a piezoelectric single crystal material, 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 interdigitated electrode layer is located on a side of the piezoelectric layer away from the substrate, and the direction of the electric field generated by the interdigitated electrode layer in the piezoelectric layer is the device direction;

[0008] Wherein, the first crystal axis is perpendicular to the wafer substrate, and the angle between the device direction and the second crystal axis is angle A1, -30°≤A1≤10°; or,

[0009] The first crystal axis is perpendicular to the wafer substrate, and the angle between the device direction and the second crystal axis is angle A2, 170°≤A2≤210°; or,

[0010] The angle between the second crystal axis and the direction perpendicular to the wafer substrate is angle B1, -20°≤B1≤40°, and the angle between the device direction and the first crystal axis is angle B2, -20°≤B2≤20°.

[0011] Optionally, the first crystal axis points from the wafer substrate to the piezoelectric layer, and the device direction is rotated in a counterclockwise direction until the angle between the first crystal axis and the second crystal axis is the angle A1.

[0012] Optionally, the first crystal axis points from the wafer substrate to the piezoelectric layer, and the device direction is rotated in a clockwise direction until the angle with the second crystal axis is the angle A2.

[0013] Optionally, the first crystal axis points from the piezoelectric layer to the wafer substrate, and the device direction is rotated in a clockwise direction until an angle A1 is formed between the first crystal axis and the second crystal axis.

[0014] Optionally, the first crystal axis points from the piezoelectric layer to the wafer substrate, and the device direction is rotated in a counterclockwise direction until the angle between the first crystal axis and the second crystal axis is the angle A2.

[0015] Optionally, the second crystal axis includes a positive direction and a reverse direction extending in opposite directions;

[0016] When the angle B1 is equal to 0°, the positive direction of the second crystal axis is from the wafer substrate to the piezoelectric layer or from the piezoelectric layer to the wafer substrate, and the device direction is rotated in the clockwise direction to an angle of the angle B2 with the first crystal axis; or,

[0017] When the angle B1 is equal to 0°, the positive direction of the second crystal axis is from the wafer substrate to the piezoelectric layer or from the piezoelectric layer to the wafer substrate, and the device direction rotates counterclockwise to an angle B2 with the first crystal axis.

[0018] Optionally, the main positioning edge of the wafer substrate is located in a first direction;

[0019] The propagation direction of the acoustic wave excited in the piezoelectric layer by the electric field generated in the piezoelectric layer by the interdigitated electrode layer forms an angle C1 with the first direction, wherein -30°≤C1≤30°.

[0020] Optionally, the interdigital electrode layer includes a plurality of first interdigital electrodes and a plurality of second interdigital electrodes;

[0021] The plurality of first interdigital electrodes are all connected to a bus bar located at 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 to the second side of the interdigital electrode layer along a second direction, and the first side is opposite to the second side;

[0022] The plurality of second interdigital electrodes are all connected to a bus bar located on 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;

[0023] 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.

[0024] Optionally, it also includes a metal layer and a sound reflection grid;

[0025] The metal layer is located on a side of the interdigital electrode layer away from the wafer substrate, and the metal layer covers at least a portion of the bus bar on the first side of the interdigital electrode layer and covers at least a portion of the bus bar on the second side of the interdigital electrode layer;

[0026] The acoustic reflection grating is located on a side of the piezoelectric layer away from the wafer substrate, and 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;

[0027] The acoustic reflection grid on each side includes a plurality of metal strips extending along the second direction; 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;

[0028] The spacing between the interdigitated electrode layer and the adjacent metal strip is greater than 0.2 times the width of the first interdigitated electrode and the second interdigitated electrode in the third direction, and less than 10 times the width of the first interdigitated electrode and the second interdigitated electrode in the third direction; wherein the third direction is parallel to the wafer substrate and perpendicular to the second direction.

[0029] In a second aspect, an embodiment of the present invention further provides an acoustic filter, which includes the resonant device as described in the first aspect above.

[0030] The resonant device provided by the embodiment of the present invention includes a wafer substrate, a piezoelectric layer and an interdigitated electrode layer; the piezoelectric layer is located on one side of the wafer substrate, the piezoelectric layer includes a piezoelectric single crystal material, 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 interdigitated electrode layer is located on the side of the piezoelectric layer away from the substrate, and the direction of the electric field generated by the interdigitated electrode layer in the piezoelectric layer is the device direction; wherein the first crystal axis is perpendicular to the wafer substrate, and the angle between the device direction and the second crystal axis is angle A1, -30°≤A1≤10°; or, the first crystal axis is perpendicular to the wafer substrate, and the angle between the device direction and the second crystal axis is angle A2, 170°≤A2≤210°; or, the angle between the second crystal axis and the direction perpendicular to the wafer substrate is angle B1, -20°≤B1≤40°, and the angle between the device direction and the first crystal axis is angle B2, -20°≤B2≤20°; that is, the present embodiment generally Through the above-mentioned bonding methods between the wafer substrate and the piezoelectric single crystal material, the maximum bulk elastic modulus of the piezoelectric single crystal material can be utilized to greatly improve the wave velocity of the surface acoustic wave propagating in the resonant device, especially greatly improve the wave velocity of the surface acoustic wave propagating in the wafer substrate and the piezoelectric layer, thereby improving the operating frequency of the resonant device. At the same time, since the present embodiment can improve the operating frequency of the resonant device only by setting the above-mentioned bonding method, there is no need to change the spacing between the interdigitated electrodes or adjust the electrode width of the resonant device, thereby ensuring the low manufacturing cost of the resonant device. In addition, since the piezoelectric single crystal material has the anisotropic characteristic, the piezoelectric layer is bonded to the wafer substrate in the above-mentioned specific directions to adjust the internal geometric shape and structure of the resonant device, which also helps to enhance the piezoelectric effect generated by the piezoelectric layer and improve the electromechanical coupling coefficient of the resonant device, thereby enhancing the performance of the resonant device. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic structural diagram of a resonant device provided by an embodiment of the present invention;

[0032] Figure 2 is a top view of a resonant device provided by an embodiment of the present invention;

[0033] Figure 3 is a cross-sectional view of a resonant device provided by an embodiment of the present invention;

[0034] Figure 4 is a schematic structural diagram of a piezoelectric single crystal material provided by an embodiment of the present invention;

[0035] Figure 5 It is a schematic structural diagram of the combination of film layers of a resonant device provided by an embodiment of the present invention;

[0036] Figure 6 is a schematic structural diagram of the combination of film layers of another resonant device provided by an embodiment of the present invention;

[0037] Figure 7 is a schematic structural diagram of the combination of film layers of another resonant device provided by an embodiment of the present invention;

[0038] Figure 8 is a schematic structural diagram of the combination of film layers of another resonant device provided by an embodiment of the present invention;

[0039] Fig. 9 It is a schematic structural diagram of the combination between a piezoelectric layer and a wafer substrate of a resonant device provided by an embodiment of the present invention;

[0040] Fig.10 is a schematic structural diagram of the combination of film layers of another resonant device provided by an embodiment of the present invention;

[0041] Fig.11 It is a schematic structural diagram of the combination between an interdigital electrode layer and a wafer substrate of a resonant device provided by an embodiment of the present invention;

[0042] Fig.12 It is a schematic structural diagram of the combination between the interdigital electrode layer and the wafer substrate of another resonant device provided by an embodiment of the present invention;

[0043] Fig.13 is a top view of another resonant device provided by an embodiment of the present invention;

[0044] Fig.14 is a cross-sectional view of another resonant device provided by an embodiment of the present invention;

[0045] Fig.15 is a cross-sectional view of another resonant device provided by an embodiment of the present invention;

[0046] Fig.16 is a top view of another resonant device provided by an embodiment of the present invention;

[0047] Fig.17 is a cross-sectional view of another resonant device provided by an embodiment of the present invention;

[0048] Fig.18 is a schematic diagram of stress distribution of a resonant device provided in an embodiment of the present invention;

[0049] Fig.19 is a schematic diagram of displacement distribution of a resonant device provided by an embodiment of the present invention;

[0050] Fig. 20 is an admittance characteristic curve of the resonant device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0051] 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.

[0052] An embodiment of the present invention provides a resonant device, Figure 1 is 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 One of the resonant devices 100 is shown as an example. 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 resonator device 100 in FIG. 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 The resonant device is shown in a cross-sectional view taken 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.

[0053] Reference and Combine Figures 1 to 4 The resonant device 100 provided by the 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, 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; the interdigital electrode layer 30 is located on a side of the piezoelectric layer 20 away from the substrate, and the direction of the electric field generated by the interdigital electrode layer 30 in the piezoelectric layer 20 is the device direction N3;

[0054] Among them, the first crystal axis X is perpendicular to the wafer substrate 10, and the angle between the device direction N3 and the second crystal axis Y is angle A1, -30°≤A1≤10°; or, the first crystal axis X is perpendicular to the wafer substrate 10, and the angle between the device direction N3 and the second crystal axis Y is angle A2, 170°≤A2≤210°; or, the angle between the second crystal axis Y and the direction perpendicular to the wafer substrate 10 is angle B1, -20°≤B1≤40°, and the angle between the device direction N3 and the first crystal axis X is angle B2, -20°≤B2≤20°.

[0055] Specifically, the material of the wafer substrate 10 may be sapphire. The wafer substrate 10 can provide support, buffering, and protection for the resonant device. Each film layer 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 the wafer-level resonant device.

[0056] The piezoelectric layer 20 may be composed of a plurality of piezoelectric single crystal materials arranged according to a certain rule, wherein the piezoelectric single crystal material refers to a single crystal material having a piezoelectric effect. Mechanical stress will be generated in the piezoelectric single crystal material under the action of an electric field, and corresponding deformation will occur due to the mechanical stress. In this embodiment, the material of the piezoelectric layer 20 may be at least one of lithium niobate, lithium tantalate or aluminum nitride.

[0057] The crystal structure has three-dimensional periodicity in spatial arrangement, and 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, lithium tantalate or aluminum nitride. In the crystal structure of the piezoelectric single crystal material, each crystal axis includes a positive direction and a negative direction extending in relative directions. The positive direction of the first crystal axis X is (+X) and the negative direction is (-X), the positive direction of the second crystal axis Y is (+Y) and the negative direction is (-Y), the positive direction of the third crystal axis Z is (+Z) and the negative direction is (-Z), the third crystal axis Z can be located on the longer body diagonal of the crystal, the midpoint of the body diagonal can be the origin of the coordinates, the first crystal axis X, the second crystal axis Y and the third crystal axis Z follow the right-hand rule, the three are 90° to each other and perpendicular to each other, and a plane perpendicular to the third crystal axis Z is made to obtain the plane where the first crystal axis X and the second crystal axis Y are located.

[0058] 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 on the piezoelectric layer 20 similar to when both hands are parallel to the piezoelectric layer 20 and the vertical projections of the two hands on the piezoelectric layer 20 do not overlap, the palms of the two hands are facing each other and the fingers of the two hands are in a cross-shaped shape. When an electrical signal (such as a power supply voltage signal, etc.) is provided to the two groups of interdigital electrodes, the two groups of interdigital electrodes will induce an electric field parallel to the wafer substrate 10 and perpendicular to the second direction N2 in the space near the piezoelectric layer 20 and the voltage layer, that is, an electric field parallel to the wafer substrate 10 and perpendicular to the second direction N2 is generated in the entire thickness direction of the piezoelectric layer 20. In this embodiment, for the convenience of explanation, the direction of the electric field generated by the two groups of interdigital electrodes in the piezoelectric layer 20 is defined as the device direction N3.

[0059] When an electric field parallel to the wafer substrate 10 and perpendicular to the second direction N2 is generated throughout the thickness direction of the piezoelectric layer 20, the piezoelectric single crystal material undergoes corresponding deformation under the action of the electric field, thereby exciting a surface acoustic wave in the piezoelectric layer 20 that propagates parallel to the wafer substrate 10 and perpendicular to the second direction N2. If the second direction N2 (i.e., the extension direction of the interdigital electrodes) is defined as the longitudinal direction, and the direction perpendicular to the second direction N2 (i.e., perpendicular to the extension direction of the interdigital electrodes, i.e., the device direction N3) is defined as the transverse direction, the piezoelectric single crystal material is polarized by the transverse electric field in the piezoelectric layer 20, and the polarization direction of the surface acoustic wave propagating in the piezoelectric layer 20 is the longitudinal direction, i.e., a longitudinally polarized acoustic wave. Finally, the surface acoustic wave is converted into a corresponding electrical signal output, and the resonant device completes the filtering work.

[0060] Based on the above content, in the technical solution of this embodiment, the film layers of the resonant device (i.e., the wafer substrate 10, the piezoelectric layer 20, and the interdigital electrode layer 30) are combined in a specific manner, that is, the piezoelectric single crystal material of the piezoelectric layer 20 is bonded to the wafer substrate 10 in a specific bonding manner to be formed on the wafer substrate 10, and the device direction N3 of the interdigital electrode layer 30 has a specific setting mode relative to the piezoelectric single crystal material of the piezoelectric layer 20, which is described in detail below:

[0061] (i) The first crystal axis X is perpendicular to the wafer substrate 10, and the angle between the device direction N3 and the second crystal axis Y is angle A1, -30°≤A1≤10°. In this case, the bonding method between the piezoelectric layer 20 and the wafer substrate 10 is that the first crystal axis X of the piezoelectric single crystal material is perpendicular to the wafer substrate 10 (for example, the positive direction (+X) of the first crystal axis X is along the direction of the wafer substrate 10 pointing to the piezoelectric layer 20 or the negative direction (-X) of the first crystal axis X is along the direction of the wafer substrate 10 pointing to the piezoelectric layer 20), and the setting relationship between the interdigitated electrode layer 30 and the piezoelectric layer 20 is that the angle between the device direction N3 and the second crystal axis Y of the piezoelectric single crystal material is any angle between -30° and 10° (for example, -25°, -20°, -15° or -10°, etc.). Exemplarily, Figure 5 is a schematic diagram of the structure of the connection between the film layers of a resonant device provided by an embodiment of the present invention. Figure 5 In the embodiment, the first crystal axis X is perpendicular to the wafer substrate 10, and the angle between the device direction N3 and the second crystal axis Y of the piezoelectric single crystal material is angle A1, wherein angle A1 is equal to -30°; Figure 6 is a schematic diagram of the structure of the combination of the film layers of another resonant device provided by an embodiment of the present invention, Figure 6 In the embodiment, the first crystal axis X is perpendicular to the wafer substrate 10, and the angle between the device direction N3 and the second crystal axis Y of the piezoelectric single crystal material is angle A1, wherein angle A1 is equal to 0°; Figure 7is a schematic diagram of the structure of the combination of the film layers of another resonant device provided by an embodiment of the present invention, Figure 7 In the embodiment, the first crystal axis X is perpendicular to the wafer substrate 10, and the angle between the device direction N3 and the second crystal axis Y of the piezoelectric single crystal material is angle A1, wherein angle A1 is equal to 10°.

[0062] (ii) The first crystal axis X is perpendicular to the wafer substrate 10, and the angle between the device direction N3 and the second crystal axis Y is angle A2, 170°≤A2≤210°. In this case, the bonding method between the piezoelectric layer 20 and the wafer substrate 10 is that the first crystal axis X of the piezoelectric single crystal material is perpendicular to the wafer substrate 10, and the setting relationship between the interdigitated electrode layer 30 and the piezoelectric layer 20 is that the angle between the device direction N3 and the second crystal axis Y of the piezoelectric single crystal material is any angle between 170° and 210° (for example, 180°, 190° or 210°, etc.). Exemplarily, Figure 8 is a schematic diagram of the structure of the combination of the film layers of another resonant device provided by an embodiment of the present invention, Figure 8 In the embodiment, the first crystal axis X is perpendicular to the wafer substrate 10, and the angle between the device direction N3 and the second crystal axis Y of the piezoelectric single crystal material is angle A2, wherein angle A2 is equal to 170°.

[0063] (III) The angle between the second crystal axis Y and the direction perpendicular to the wafer substrate 10 is angle B1, -20°≤B1≤40°, and the angle between the device direction N3 and the first crystal axis X is angle B2, -20°≤B2≤20°. In this case, the bonding method between the piezoelectric layer 20 and the wafer substrate 10 is that the angle between the second crystal axis Y of the piezoelectric single crystal material and the direction perpendicular to the wafer substrate 10 is any angle between -20° and 40° (for example, -10°, 0°, 10°, 20° or 30°, etc.), and the setting relationship between the interdigitated electrode layer 30 and the piezoelectric layer 20 is that the angle between the device direction N3 and the first crystal axis X of the piezoelectric single crystal material is any angle between -20° and -20° (for example, -10°, 0° or 10°, etc.). Exemplarily, Fig. 9 Schematic diagram of the structure of the piezoelectric layer and the wafer substrate of a resonant device provided by an embodiment of the present invention. Fig. 9 In (a), the angle between the positive direction (+Y) of the second crystal axis Y of the piezoelectric single crystal material and the direction L perpendicular to the wafer substrate 10 is angle B1, wherein angle B1 is equal to 40°, and the direction L perpendicular to the wafer substrate 10 is along the direction of the wafer substrate 10 pointing to the piezoelectric layer 20; Fig. 9 In (b), the angle between the positive direction (+Y) of the second crystal axis Y of the piezoelectric single crystal material and the direction L perpendicular to the wafer substrate 10 is angle B1, wherein angle B1 is equal to -20°, and the direction L perpendicular to the wafer substrate 10 is along the direction of the wafer substrate 10 pointing to the piezoelectric layer 20; Fig. 9In (c), the angle between the positive direction (+Y) of the second crystal axis Y of the piezoelectric single crystal material and the direction L perpendicular to the wafer substrate 10 is angle B1, wherein angle B1 is equal to 40°, and the direction L perpendicular to the wafer substrate 10 is along the piezoelectric layer 20 pointing to the direction of the wafer substrate 10; Fig. 9 In (d), the angle between the positive direction (+Y) of the second crystal axis Y of the piezoelectric single crystal material and the direction L perpendicular to the wafer substrate 10 is angle B1, wherein angle B1 is equal to -20°, and the direction L perpendicular to the wafer substrate 10 is along the piezoelectric layer 20 pointing to the direction of the wafer substrate 10; accordingly, Fig. 9 It can be seen that in this embodiment, the piezoelectric single crystal material of the piezoelectric layer 20 can be bonded to the surface of the wafer substrate 10 in a variety of different ways; Fig.10 is a schematic diagram of the structure of the combination of the film layers of another resonant device provided by an embodiment of the present invention, Fig.10 In (a), the angle between the second crystal axis Y of the piezoelectric single crystal material and the direction perpendicular to the wafer substrate 10 is angle B1, where angle B1 is equal to -20°, and the angle between the device direction N3 and the first crystal axis X of the piezoelectric material is angle B2, where angle B2 is equal to -20°.

[0064] This embodiment improves the operating frequency and performance of the resonant device by combining the film layers (i.e., the wafer substrate 10, the piezoelectric layer 20, and the interdigital electrode layer 30) of the above-mentioned resonant devices. The principle is:

[0065] The wave velocity of sound waves propagating in solid materials depends on the bulk elastic modulus and density of the solid material; the larger the ratio of the bulk elastic modulus to the density, the larger the wave velocity; the ratio of the bulk elastic modulus to the density of the sapphire wafer substrate 10 is extremely high, and the bulk elastic modulus of the piezoelectric single crystal material has various anisotropies (its values ​​are different in each lattice direction). The above-mentioned bonding methods of the sapphire wafer substrate 10 and the piezoelectric single crystal material, that is, the above-mentioned several combining methods, can utilize the maximum bulk elastic modulus of the piezoelectric single crystal material. Therefore, this embodiment greatly improves the wave velocity of the surface acoustic wave propagating in the resonant device through the above-mentioned several combining methods, especially greatly improves the wave velocity of the surface acoustic wave propagating in the wafer substrate 10 and the piezoelectric layer 20.

[0066] Since f=v / (2*Wpi), where f is the operating frequency of the resonant device, v is the wave velocity of the surface acoustic wave propagating in the resonant device, and Wpi is the spacing between the interdigitated electrodes, the present embodiment improves the operating frequency of the resonant device by increasing the wave velocity v of the surface acoustic wave propagating in the wafer substrate 10 and the piezoelectric layer 20 without changing the spacing between the interdigitated electrodes. At the same time, since the present embodiment can improve the operating frequency of the resonant device only by setting the above-mentioned combination method, without changing the spacing between the interdigitated electrodes or adjusting the electrode width of the resonant device, the low manufacturing cost of the resonant device is ensured. In addition, the piezoelectric layer 20 is bonded to the wafer substrate 10 in the above-mentioned specific directions, so that the angle formed by the placement direction of the resonant device and the main positioning edge of the wafer substrate 10 is smaller, thereby maximizing the utilization rate of the wafer substrate 10.

[0067] Since the piezoelectric single crystal material has the anisotropic characteristic, the piezoelectric layer 20 is bonded to the wafer substrate 10 in the above-mentioned specific directions to adjust the internal geometry and structure of the resonant device, which also helps to enhance the piezoelectric effect generated by the piezoelectric layer 20 and improve the electromechanical coupling coefficient of the resonant device, thereby enhancing the performance of the resonant device.

[0068] In summary, the technical solution of the embodiment of the present invention solves the technical problem that both SAW resonant devices and BAW resonant devices in the prior art cannot take into account low manufacturing cost, high operating frequency and performance of the resonant devices. While ensuring the low manufacturing cost of the resonant device, the operating frequency and performance of the resonant device are improved, which is conducive to meeting the requirements of 5G communication standards.

[0069] The following further refines the relationship between the film layers of the resonant device (i.e., the wafer substrate 10, the piezoelectric layer 20, and the interdigital electrode layer 30) by combining the above-mentioned situations:

[0070] Optionally, the first crystal axis X points from the wafer substrate 10 to the piezoelectric layer 20 , and the device direction N3 rotates counterclockwise to an angle A1 with the second crystal axis Y.

[0071] Specifically, this method is a refinement of the above situation (I), the first crystal axis X of the piezoelectric single crystal material points out of the plane of the wafer substrate 10, and the device direction N3 can be rotated in the counterclockwise direction to an angle between -30° and 10° with the second crystal axis Y of the piezoelectric single crystal material. For example, reference can be made to Figure 7 In the figure, the first crystal axis X of the piezoelectric single crystal material points out of the plane of the wafer substrate 10, and the device direction N3 rotates counterclockwise to an angle A1 with the second crystal axis Y of the piezoelectric single crystal material, wherein the angle A1 is equal to 10°.

[0072] Optionally, the first crystal axis X points from the wafer substrate 10 to the piezoelectric layer 20 , and the device direction N3 rotates in a clockwise direction to an angle A2 with the second crystal axis Y.

[0073] Specifically, this method is a refinement of the above situation (two), the first crystal axis X of the piezoelectric single crystal material points out of the plane of the wafer substrate 10, and the device direction N3 can be rotated in a clockwise direction to any angle between 170° and 210° with the second crystal axis Y of the piezoelectric single crystal material.

[0074] Optionally, the first crystal axis X points from the piezoelectric layer 20 to the wafer substrate 10 , and the device direction N3 rotates in a clockwise direction to an angle A1 with the second crystal axis Y.

[0075] Specifically, this method is a refinement of the above situation (I), the first crystal axis X of the piezoelectric single crystal material points to the plane of the wafer substrate 10, and the device direction N3 can be rotated in the clockwise direction to an angle between -30° and 10° with the second crystal axis Y of the piezoelectric single crystal material. Figure 5 In the figure, the first crystal axis X of the piezoelectric single crystal material points to the plane of the wafer substrate 10, and the device direction N3 is rotated in the clockwise direction to an angle A1 with the second crystal axis Y of the piezoelectric single crystal material, wherein the angle A1 is equal to -30°.

[0076] Optionally, the first crystal axis X points from the piezoelectric layer 20 to the wafer substrate 10 , and the device direction N3 rotates counterclockwise to form an angle A2 with the second crystal axis Y.

[0077] Specifically, this method is a refinement of the above situation (ii), the first crystal axis X of the piezoelectric single crystal material points to the plane of the wafer substrate 10, and the device direction N3 can be rotated in the counterclockwise direction to any angle between 170° and 210° with the second crystal axis Y of the piezoelectric single crystal material. Figure 8 In the figure, the first crystal axis X of the piezoelectric single crystal material points to the plane of the wafer substrate 10, and the device direction N3 rotates counterclockwise to an angle A2 with the second crystal axis Y of the piezoelectric single crystal material, wherein the angle A2 is equal to 170°.

[0078] Optionally, when the angle B1 is equal to 0°, the second crystal axis Y points from the wafer substrate 10 to the piezoelectric layer 20 or from the piezoelectric layer 20 to the wafer substrate 10, and the device direction N3 rotates in a clockwise direction to form an angle B2 with the first crystal axis X; or, when the angle B1 is equal to 0°, the second crystal axis Y points from the wafer substrate 10 to the piezoelectric layer 20 or from the piezoelectric layer 20 to the wafer substrate 10, and the device direction N3 rotates in a counterclockwise direction to form an angle B2 with the first crystal axis X.

[0079] Specifically, this method is a refinement of the above situation (three). When the angle B1 is equal to 0°, the second crystal axis Y of the piezoelectric single crystal material points to the plane of the wafer substrate 10 or outside the plane (that is, the second crystal axis Y points to the wafer substrate 10 along the piezoelectric layer 20 or points to the piezoelectric layer along the wafer substrate 10), and the device direction N3 can be rotated in the counterclockwise direction or the clockwise direction to any angle between -20° and 20° with the first crystal axis X of the piezoelectric single crystal material. For example, reference can be made to Fig.10 ,exist Fig.10 In (b), when the angle B1 is equal to 0°, the second crystal axis Y of the piezoelectric single crystal material points out of the plane or out of the plane of the wafer substrate 10, and the device direction N3 rotates counterclockwise to an angle of -20° with the first crystal axis X of the piezoelectric single crystal material.

[0080] In this embodiment, not only the device direction N3 of the interdigital electrode layer 30 has a specific configuration relative to the piezoelectric single crystal material of the piezoelectric layer 20 , but also the device direction N3 of the interdigital electrode layer 30 may have a specific configuration relative to the wafer substrate 10 . Fig.11 1 is a schematic structural diagram of a resonant device provided by an embodiment of the present invention, wherein an interdigitated electrode layer 30 and a wafer substrate 10 are combined. Fig.12 1 is a schematic diagram of the structure of another resonant device provided by an embodiment of the present invention, wherein the interdigital electrode layer 30 is combined with the wafer substrate 10. The main positioning edge 11 of the wafer substrate 10 is located in the first direction N1, and the propagation direction of the acoustic wave excited in the piezoelectric layer 20 by the electric field generated in the piezoelectric layer 20 by the interdigital electrode layer 30 is at an angle C1 with the first direction N1, -30°≤C1≤30°.

[0081] Specifically, the propagation direction of the acoustic wave excited in the piezoelectric layer 20 by the electric field generated in the piezoelectric layer 20 by the interdigitated electrode layer 30 is also the device direction N3 in this embodiment, and the angle between the device direction N3 and the first direction N1 (i.e., the main positioning edge of the wafer substrate 10) is any angle between -30° and 30°. Fig.11 , Fig.11 The schematic diagram shows the situation where the angle between the device direction N3 and the first direction N1 is -30°. Figure 1 , Figure 1 The schematic diagram shows the situation where the angle between the device direction N3 and the first direction N1 is 0°. Fig.12 , Fig.12 The schematic diagram shows a situation where the angle between the device direction N3 and the first direction N1 is 30°.

[0082] The piezoelectric layer 20 will generate mechanical stress and undergo corresponding deformation under the action of the electric field applied by the interdigitated electrode layer 30, thereby exciting surface acoustic waves propagating along the device direction N3 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 interdigitated electrodes and the wafer substrate 10 by setting the angle between the device direction N3 and the first direction N1 to be greater than or equal to -30° or less than or equal to 30°, and further utilizes the maximum bulk elastic modulus of the piezoelectric single crystal material to enhance the piezoelectric effect generated by the piezoelectric layer 20 and improve 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.

[0083] Optionally, refer to Figure 2 and Figure 3 The interdigitated electrode layer 30 includes a plurality of first interdigitated electrodes 310 and a plurality of second interdigitated electrodes 320; the plurality of first interdigitated electrodes 310 are all connected to a bus bar 311 located on a first side of the interdigitated electrode layer, and the first interdigitated electrodes 310 are all extended from the first side of the interdigitated electrode layer along a second direction N2 to the second side of the interdigitated electrode layer, and the first side is opposite to the second side; the plurality of second interdigitated electrodes 320 are all connected to a bus bar 321 located on the second side of the interdigitated electrode layer, and the second interdigitated electrodes 320 are all extended from the second side along the second direction N2 to the first side; the vertical projections of the first interdigitated electrodes 310 and the second interdigitated electrodes 320 on the piezoelectric layer 20 are alternating, and the first interdigitated electrodes 310 and the second interdigitated electrodes 320 are insulated from each other.

[0084] 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 100 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 a 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 device direction N3, so that the electric field in the device direction N3 is generated throughout the thickness direction of the piezoelectric layer 20, thereby exciting the surface acoustic wave propagating along the device direction N3, that is, the longitudinally polarized acoustic wave, and converting the surface acoustic wave into a corresponding electrical signal output to achieve filtering.

[0085] 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.

[0086] 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.14Optionally, 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 (that is, the device direction N3) is greater than a width We of the first interdigitated electrode 310 and the second interdigitated electrode 320 in the third direction (that is, the device 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 (i.e., the device direction N3); wherein the third direction (i.e., the device 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.

[0087] 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.

[0088] 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.14The schematic diagram shows the case where the widths of the first interdigitated electrode 310 and the second interdigitated electrode 320 in the third direction (i.e., the device direction N3) are both We. In this embodiment, by setting the width of the metal strip 331 in the third direction (i.e., the device 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 grating, thereby further reducing the surface acoustic waves propagating from the resonant device to the outside of the sound reflection grating 330 on both sides, helping to confine the surface acoustic waves to the inside of the resonant device along the third direction (i.e., the device direction N3), thereby improving the energy conversion efficiency between electrical energy and mechanical energy of the resonant device.

[0089] Combination Fig.13 and Fig.14 On 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 (ie, the device 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.

[0090] 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 (i.e., the device direction N3), thereby improving the energy conversion efficiency between electrical energy and mechanical energy of the resonant device.

[0091] 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.

[0092] 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 (that is, the device direction N3) and the center of the adjacent second interdigital electrode 320 along the third direction (that is, the device 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.

[0093] Combination Fig.13 and Fig.14 Optionally, the thickness of the first interdigitated electrode 310 and the second interdigitated electrode 320 in the direction perpendicular to the wafer substrate 10 is 50nm<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.

[0094] 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.

[0095] 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 .

[0096] 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 the humidity and oxidation in the environment, 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.

[0097] 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 100 further 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.

[0098] 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.

[0099] 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.13 The stress distribution of each film layer of the resonant device is shown. Fig.13 , Fig.14 and Fig.18Under 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. Fig.18 As shown in the figure, the stress at the position corresponding to the first interdigitated electrode 310 and the second interdigitated electrode 320 in the piezoelectric layer 20 reaches a maximum value (close to Max), and the stress at the position corresponding to the first interdigitated electrode 310 and the second interdigitated electrode 320 in the piezoelectric layer 20 reaches a minimum value (close to -Max).

[0100] Fig.19 is a schematic diagram of the vibration displacement distribution of the resonant device provided by an embodiment of the present invention, Fig.19 It schematically shows that under the action of electric field, Fig.13 The vibration displacement distribution of each membrane layer of the resonant device is shown. Fig.13 , Fig.14 and Fig.19 The vibration 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 . Fig.19 As shown in the figure, the vibration displacement at the position corresponding to the first interdigitated electrode 310 and the second interdigitated electrode 320 in the piezoelectric layer 20 reaches a minimum value (close to Min), and the vibration displacement at the position corresponding to the first interdigitated electrode 310 and the second interdigitated electrode 320 in the piezoelectric layer 20 reaches a maximum value (close to Max).

[0101] 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.14 The admittance characteristic curve obtained by simulation experiment of the resonant device shown in the figure. Fig. 20 As shown in (a), the resonance frequency of the resonant device provided by the embodiment of the present invention is 1.75 GHz, that is, the operating frequency, and the corresponding electromechanical coupling coefficient Kt 2 Can reach 32.7%, such as Fig. 20 As shown in (b), Fig. 20 (b) is Fig. 20The wide frequency response of (a) is 0.1 GHz to 4 GHz under the same parameters. It can be seen that the scheme of this embodiment helps to improve the electromechanical coupling coefficient and the operating frequency of the resonant device, and helps 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 interdigital electrodes, and the size and position of the acoustic reflection grid relative to the interdigital electrodes.

[0102] The embodiment of the present invention further provides an acoustic filter, which includes a resonant device as described in any of the above technical solutions. The acoustic filter provided by the embodiment of the present invention and the resonant device provided in any of the above technical solutions belong to the same inventive concept, and both can achieve the same technical effect, and the repeated contents will not be repeated.

[0103] 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: It includes a wafer substrate, a piezoelectric layer and an interdigital electrode layer; The piezoelectric layer is located on one side of the wafer substrate, the piezoelectric layer includes a piezoelectric single crystal material, 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 interdigitated electrode layer is located on a side of the piezoelectric layer away from the substrate, and the direction of the electric field generated by the interdigitated electrode layer in the piezoelectric layer is the device direction; Wherein, the first crystal axis is perpendicular to the wafer substrate, and the angle between the device direction and the second crystal axis is angle A1, -30°≤A1≤10°; or, The first crystal axis is perpendicular to the wafer substrate, and the angle between the device direction and the second crystal axis is angle A2, 170°≤A2≤210°; or, The angle between the second crystal axis and the direction perpendicular to the wafer substrate is an angle B1, -20°≤B1≤40°, and the angle between the device direction and the first crystal axis is an angle B2, -20°≤B2≤20°; The first crystal axis points from the wafer substrate to the piezoelectric layer, and the device direction rotates counterclockwise to an angle A1 with the second crystal axis; The first crystal axis points from the wafer substrate to the piezoelectric layer, and the device direction rotates in a clockwise direction until the angle with the second crystal axis is the angle A2.

2. The resonant device according to claim 1, characterized in that: The first crystal axis points from the piezoelectric layer to the wafer substrate, and the device direction rotates in a clockwise direction until the angle A1 formed with the second crystal axis.

3. The resonant device according to claim 1, characterized in that: The first crystal axis points from the piezoelectric layer to the wafer substrate, and the device direction rotates counterclockwise to an angle A2 with the second crystal axis.

4. The resonant device according to claim 1, characterized in that: The second crystal axis includes a positive direction and a reverse direction extending in opposite directions; When the angle B1 is equal to 0°, the positive direction of the second crystal axis is from the wafer substrate to the piezoelectric layer or from the piezoelectric layer to the wafer substrate, and the device direction rotates in the clockwise direction until the angle with the first crystal axis is the angle B2; or, When the angle B1 is equal to 0°, the positive direction of the second crystal axis is from the wafer substrate to the piezoelectric layer or from the piezoelectric layer to the wafer substrate, and the device direction rotates counterclockwise to an angle B2 with the first crystal axis.

5. The resonant device according to claim 1, characterized in that: The main positioning edge of the wafer substrate is located in a first direction; The propagation direction of the acoustic wave excited in the piezoelectric layer by the electric field generated in the piezoelectric layer by the interdigitated electrode layer forms an angle C1 with the first direction, wherein -30°≤C1≤30°.

6. The resonant device according to claim 1, characterized in that: 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 at 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 to the second side of the interdigital electrode layer along a second direction, and the first side is opposite to the second side; The plurality of second interdigital electrodes are all connected to a bus bar located on 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.

7. The resonant device according to claim 6, characterized in that: Also includes a metal layer and a sound reflection grid; The metal layer is located on a side of the interdigital electrode layer away from the wafer substrate, and the metal layer covers at least a portion of the bus bar on the first side of the interdigital electrode layer and covers at least a portion of the bus bar on the second side of the interdigital electrode layer; The acoustic reflection grating is located on a side of the piezoelectric layer away from the wafer substrate, and 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; The acoustic reflection grid on each side includes a plurality of metal strips extending along the second direction; 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; The spacing between the interdigitated electrode layer and the adjacent metal strip is greater than 0.2 times the width of the first interdigitated electrode and the second interdigitated electrode in the third direction, and less than 10 times the width of the first interdigitated electrode and the second interdigitated electrode in the third direction; wherein the third direction is parallel to the wafer substrate and perpendicular to the second direction.

8. An acoustic filter, characterized in that: Comprising the resonant device according to any one of claims 1 to 7.

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