A lamb wave resonator and a lamb wave filter

Abstract

The application provides a Lamb wave resonator and a Lamb wave filter. The Lamb wave resonator comprises a supporting substrate, an acoustic Bragg reflector, a piezoelectric layer, an interdigital transducer and a dielectric layer. The dielectric layer is arranged on the side of the electrode fingers of the interdigital transducer away from the supporting substrate, and covers the electrode fingers and part of the piezoelectric layer. Between two adjacent electrode fingers, a recessed area is formed between the piezoelectric layer not covered by the dielectric layer and the dielectric layer. The acoustic Bragg reflector comprises a first low acoustic impedance layer and at least one impedance layer group. The impedance layer group comprises at least one high acoustic impedance layer and at least one second low acoustic impedance layer. The thickness of the first low acoustic impedance layer is greater than the thickness of the second low acoustic impedance layer. The spurious wave of the Lamb wave resonator is suppressed, the energy loss of the Lamb wave resonator is reduced, and the quality factor of the Lamb wave resonator is improved.

Description

Technical Field

[0001] This invention relates to the field of radio frequency technology, and in particular to a Lamb wave resonator and a Lamb wave filter. Background Technology

[0002] As 5G communication technology evolves into 6G, the performance requirements for radio frequency (RF) front-end filters are becoming increasingly stringent, especially in achieving low insertion loss, high bandwidth, and high selectivity at high frequencies. Traditional SAW and BAW filters suffer from high high-frequency losses and limited bandwidth, making them unsuitable for millimeter-wave band requirements. Lamb wave resonators, with their high electromechanical coupling coefficient, can be adapted to high-frequency broadband scenarios. However, existing Lamb wave resonators exhibit significant clutter, high energy loss, and a low quality factor. Summary of the Invention

[0003] This invention provides a Lamb wave resonator and a Lamb wave filter to suppress noise in the Lamb wave resonator, reduce energy loss in the Lamb wave resonator, and improve the quality factor of the Lamb wave resonator.

[0004] According to one aspect of the present invention, a Lamb wave resonator is provided, the Lamb wave resonator comprising: Support substrate, acoustic Bragg reflector, piezoelectric layer, interdigital transducer and dielectric layer; The acoustic Bragg reflector is disposed on the first surface of the supporting substrate; The piezoelectric layer is disposed on the side of the acoustic Bragg reflector away from the supporting substrate; The interdigital transducer is disposed on the side of the piezoelectric layer away from the supporting substrate; The interdigital transducer includes multiple electrode fingers; The dielectric layer is disposed on the side of the interdigital transducer away from the supporting substrate, and the dielectric layer covers the electrode finger and a portion of the piezoelectric layer; Between two adjacent electrode fingers, a recessed region is formed between the piezoelectric layer, which is not covered by the dielectric layer, and the dielectric layer; The acoustic Bragg reflector includes a first low acoustic impedance layer and at least one group of impedance layers; The impedance layer group is disposed on the first surface of the support substrate, and the first low acoustic impedance layer is disposed on the side of the impedance layer group away from the support substrate. Each of the impedance layer groups includes a high acoustic impedance layer and a second low acoustic impedance layer that are alternately stacked along the thickness direction of the impedance layer group, wherein the high acoustic impedance layer is disposed on the side of the second low acoustic impedance layer away from the support substrate. The thickness of the first low acoustic impedance layer is greater than the thickness of the second low acoustic impedance layer.

[0005] Optionally, the ratio of the length of the recessed region in the direction of Lamb wave propagation to the wavelength of the Lamb wave is greater than or equal to 0.3.

[0006] Optionally, the thickness range of the dielectric layer may vary depending on the material of the dielectric layer. The dielectric layer is made of one of silicon oxide, silicon nitride, aluminum nitride, and aluminum oxide.

[0007] Optionally, when the dielectric layer is made of silicon oxide, the ratio of the thickness of the dielectric layer to the thickness of the piezoelectric layer is greater than or equal to 0.45 and less than or equal to 0.52. When the dielectric layer is made of silicon nitride, the ratio of the thickness of the dielectric layer to the thickness of the piezoelectric layer is greater than or equal to 0.22 and less than or equal to 0.43. When the dielectric layer is made of aluminum nitride, the ratio of the thickness of the dielectric layer to the thickness of the piezoelectric layer is greater than or equal to 0.35 and less than or equal to 0.43. When the dielectric layer is made of aluminum oxide, the ratio of the thickness of the dielectric layer to the thickness of the piezoelectric layer is greater than or equal to 0.43 and less than or equal to 0.52.

[0008] Optionally, the ratio of the thickness of the first low acoustic impedance layer to the thickness of the second low acoustic impedance layer is greater than or equal to 2.

[0009] Optionally, the Euler angle of the piezoelectric layer is (0°, 0°, 90°), (0°, 38°, 0°), or (0°, 30°, 0°).

[0010] Optionally, the materials of the first low acoustic impedance layer and the second low acoustic impedance layer include silicon oxide; The high acoustic impedance layer includes at least one of tantalum oxide, silicon nitride, aluminum nitride, silicon carbide, molybdenum, tungsten, gold, or platinum.

[0011] Optionally, the Lamb wave includes a third-order antisymmetric Lamb wave mode and / or a second-order symmetric Lamb wave mode.

[0012] Optionally, the Lamb wave resonator also includes: The transmitter electrodes and transmitter busbar are arranged along the electrode finger arrangement direction of the interdigital transducer, and the transmitter electrodes are symmetrically distributed on both sides of the interdigital transducer; Along the extension direction of the electrode fingers of the interdigital transducer, the transmitter busbars are symmetrically distributed on both sides of the transmitter electrodes; The interdigital transducer includes a first electrode finger, a second electrode finger, and an interdigital transducer busbar.

[0013] According to another aspect of the present invention, a Lamb wave filter is provided, the Lamb wave filter comprising a series arm resonator and a parallel arm resonator, wherein at least one of the series arm resonator and the parallel arm resonator is a Lamb wave resonator as described in any of the above embodiments.

[0014] The Lamb wave resonator provided in this embodiment of the invention includes a support substrate, an acoustic Bragg reflector, a piezoelectric layer, an interdigital transducer, and a dielectric layer. The acoustic Bragg reflector is disposed on a first surface of the support substrate; the piezoelectric layer is disposed on the side of the acoustic Bragg reflector away from the support substrate; the interdigital transducer is disposed on the side of the piezoelectric layer away from the support substrate; the dielectric layer is disposed on the side of the interdigital transducer's electrode finger away from the support substrate, and the dielectric layer covers the electrode finger and a portion of the piezoelectric layer; a recessed region is formed between two adjacent electrode fingers, between the piezoelectric layer not covered by the dielectric layer and the dielectric layer; the acoustic Bragg reflector includes a first low acoustic impedance layer and at least one impedance layer group, the impedance layer group including at least one high acoustic impedance layer and at least one second low acoustic impedance layer, the high acoustic impedance layer and the second low acoustic impedance layer are alternately stacked along the thickness direction of the impedance layer group; the thickness of the first low acoustic impedance layer is greater than the thickness of the second low acoustic impedance layer. By covering the electrode fingers with a dielectric layer and partially covering the piezoelectric layer, a recessed region is formed between adjacent electrode fingers where the piezoelectric layer is not covered by the dielectric layer. This creates a discontinuity in the acoustic impedance of the recessed region, thereby disrupting the phase matching condition of stray modes and suppressing stray resonances in the resonator. By setting the thickness of the first low acoustic impedance layer to be greater than that of the second low acoustic impedance layer, the excitation mode can be controlled. Simultaneously, precisely adjusting the thickness of the dielectric layer can alter the stress distribution along the thickness direction of each vibration mode in the resonator, suppressing the conversion of higher-order mode piezoelectric electrical energy to mechanical energy, eliminating stray resonance peaks, reducing the energy loss of the Lamb wave resonator, and improving the quality factor of the Lamb wave resonator.

[0015] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a top view schematic diagram of a Lamb wave resonator provided in an embodiment of the present invention; Figure 2This is a cross-sectional view of a Lamb wave resonator along section line AA1 provided in an embodiment of the present invention; Figure 3 This is a comparison diagram of admittance-frequency curves of Lamb wave resonators with different indentation lengths provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of a Lamb wave resonator with a dielectric layer covering the electrode fingers and a piezoelectric layer. Figure 5 This is a schematic diagram of a Lamb wave resonator structure without a dielectric layer on the electrode fingers and piezoelectric layer. Figure 6 This is a comparison diagram of admittance-frequency curves of Lamb wave resonators corresponding to different ratios of dielectric layer thickness to piezoelectric layer thickness provided in an embodiment of the present invention; Figure 7 This is a comparison of admittance-frequency curves of Lamb wave resonators corresponding to different ratios of dielectric layer thickness to piezoelectric layer thickness provided in this embodiment of the invention. Figure 8 This is a comparison diagram of admittance-frequency curves of Lamb wave resonators corresponding to different ratios of dielectric layer thickness to piezoelectric layer thickness provided in this embodiment of the invention; Figure 9 This is a comparison diagram of admittance-frequency curves of Lamb wave resonators corresponding to different ratios of dielectric layer thickness to piezoelectric layer thickness provided in this embodiment of the invention; Figure 10 This is an admittance-frequency curve of a Lamb wave resonator whose thickness ratio of the first low acoustic impedance layer to the second low acoustic impedance layer is greater than or equal to 2, as provided in an embodiment of the present invention. Figure 11 This is a schematic diagram of the Lamb wave resonator in the comparative embodiment; Figure 12 This is the admittance-frequency curve of the Lamb wave resonator in the comparative embodiment; Figure 13 This is a comparison diagram of the admittance-frequency curves of another Lamb wave resonator in the comparative embodiment; Figure 14 This is a schematic diagram of the structure of a Lamb wave filter provided in an embodiment of the present invention. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0019] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0020] This invention provides a Lamb wave resonator. Figure 1 This is a top view schematic diagram of a Lamb wave resonator provided in an embodiment of the present invention. Figure 2 A cross-sectional view of a Lamb wave resonator along section line AA1 provided in an embodiment of the present invention, with reference to... Figure 1 and Figure 2 Lamb wave resonators include: Support substrate 10, acoustic Bragg reflector 20, piezoelectric layer 30, interdigital transducer 40 and dielectric layer 50; Acoustic Bragg reflector 20 is disposed on the first surface of support substrate 10; The piezoelectric layer 30 is disposed on the side of the acoustic Bragg reflector 20 away from the support substrate 10; The interdigital transducer 40 is disposed on the side of the piezoelectric layer 30 away from the support substrate 10; The interdigital transducer 40 includes multiple electrode fingers 41; The dielectric layer 50 is disposed on the side of the interdigital transducer 40 away from the support substrate 10, and the dielectric layer 50 covers the electrode finger 41 and a portion of the piezoelectric layer 30. Between two adjacent electrode fingers 41, a recessed region 60 is formed between the piezoelectric layer 30, which is not covered by the dielectric layer 50, and the dielectric layer 50. The acoustic Bragg reflector 20 includes a first low acoustic impedance layer 21 and at least one impedance layer group 24; Impedance layer group 24 is disposed on the first surface of support substrate 10, and first low acoustic impedance layer 21 is disposed on the side of impedance layer group 24 away from support substrate 10. Each impedance layer group 24 includes a high acoustic impedance layer 22 and a low acoustic impedance layer 23 that are alternately stacked along the thickness direction of the impedance layer group 24, with the high acoustic impedance layer 22 disposed on the side of the second low acoustic impedance layer 23 away from the support substrate 10. The thickness of the first low acoustic impedance layer 21 is greater than the thickness of the second low acoustic impedance layer 23.

[0021] Specifically, the support substrate 10 is made of a material with high sound velocity, and the support substrate 10 is a high sound velocity component. The piezoelectric layer 30 is a thin single-crystal layer made of piezoelectric material. The piezoelectric material may include lithium niobate, lithium tantalate, gallium nitride, aluminum nitride, or zinc oxide, etc. For example, the material of the piezoelectric layer 30 may be lithium niobate. The acoustic Bragg reflector 20 is used to reflect the sound wave energy back to the piezoelectric layer 30, preventing the sound wave from leaking towards the support substrate 10, thereby achieving effective confinement of the sound wave without the need for back cavity etching. The interdigital transducer 40 is used to convert the electrical signal into a Lamb wave in the piezoelectric layer 30. Here, the X-axis direction is the arrangement direction of the electrode fingers 41, which is also the direction of elastic wave propagation; the Y-axis direction is the extension direction of the electrode fingers 41; and the Z-axis direction is the height direction of the Lamb wave resonator, that is, the thickness direction of the acoustic Bragg reflector 20.

[0022] By setting a dielectric layer 50 to cover the electrode fingers 41 and partially cover the piezoelectric layer 30, a recessed region 60 is formed between two adjacent electrode fingers 41, between the piezoelectric layer 30 not covered by the dielectric layer 50 and the dielectric layer 50. This causes the acoustic impedance of the recessed region 60 to be discontinuous, thereby disrupting the phase matching condition of the stray mode and suppressing stray resonance in the Lamb wave resonator.

[0023] By setting the thickness of the first low acoustic impedance layer 21 to be greater than the thickness of the second low acoustic impedance layer 23, the excitation mode can be controlled. By precisely adjusting the thickness of the dielectric layer 50, the stress distribution of each vibration mode in the resonator along the thickness direction can be changed, the conversion capability of higher-order mode piezoelectric energy and mechanical energy can be suppressed, clutter resonance peaks can be eliminated, the energy loss of the Lamb resonator can be reduced, and the quality factor (Q value) of the Lamb resonator can be improved.

[0024] The Lamb wave resonator provided in this embodiment of the invention includes a support substrate 10, an acoustic Bragg reflector 20, a piezoelectric layer 30, an interdigital transducer 40, and a dielectric layer 50. The acoustic Bragg reflector 20 is disposed on a first surface of the support substrate 10; the piezoelectric layer 30 is disposed on the side of the acoustic Bragg reflector 20 away from the support substrate 10; the interdigital transducer 40 is disposed on the side of the piezoelectric layer 30 away from the support substrate 10; and the dielectric layer 50 is disposed on the side of the interdigital transducer 40 whose electrode fingers 41 are away from the support substrate 10, covering the electrode fingers 41. A piezoelectric layer 30 is partially covered by a dielectric layer 50. Between two adjacent electrode fingers 41, a recessed region 60 is formed between the piezoelectric layer 30 not covered by the dielectric layer 50 and the dielectric layer 50. The acoustic Bragg reflector 20 includes a first low acoustic impedance layer 21 and at least one impedance layer group 24. The impedance layer group 24 includes at least one high acoustic impedance layer 22 and at least one second low acoustic impedance layer 23. The high acoustic impedance layer 22 and the second low acoustic impedance layer 23 are alternately stacked along the thickness direction of the impedance layer group 24. The thickness of the first low acoustic impedance layer 21 is greater than the thickness of the second low acoustic impedance layer 23. By setting the dielectric layer 50 to cover the electrode fingers 41 and partially cover the piezoelectric layer 30, a recessed region 60 is formed between two adjacent electrode fingers 41, between the piezoelectric layer 30 not covered by the dielectric layer 50 and the dielectric layer 50. This causes the acoustic impedance of the recessed region 60 to be discontinuous, thereby disrupting the phase matching condition of the stray mode and suppressing stray resonance in the resonator. By setting the thickness of the first low acoustic impedance layer 21 to be greater than the thickness of the second low acoustic impedance layer 23, the excitation mode can be controlled. By precisely adjusting the thickness of the dielectric layer 50, the stress distribution of each vibration mode in the resonator along the thickness direction can be changed, the conversion capability of higher-order mode piezoelectric energy and mechanical energy can be suppressed, clutter resonance peaks can be eliminated, the energy loss of the Lamb resonator can be reduced, and the quality factor of the Lamb resonator can be improved.

[0025] Optionally, the ratio of the length of the recessed region 60 in the direction of Lamb wave propagation to the wavelength of the Lamb wave is greater than or equal to 0.3.

[0026] Specifically, Figure 3 This is a comparison diagram of admittance-frequency curves for Lamb wave resonators with different indentation lengths provided in an embodiment of the present invention. Figure 4 A schematic diagram of a Lamb wave resonator with a dielectric layer covering electrode fingers and a piezoelectric layer. Figure 5 This is a schematic diagram of a Lamb wave resonator structure without a dielectric layer on the electrode fingers and piezoelectric layer, for reference. Figures 2-5 Let the wavelength of the Lamb wave be λ. Figure 3The blue curve represents the admittance-frequency curve for a length of 0.3λ in the Lamb wave propagation direction of the recessed region 60; the red curve represents the admittance-frequency curve for a length of 0 in the Lamb wave propagation direction of the recessed region 60, i.e., when the dielectric layer 50 covers the electrode finger 41 and the piezoelectric layer 30 in the resonator; and the black curve represents the admittance-frequency curve for the electrode finger 41 and the piezoelectric layer 30 in the resonator without the dielectric layer 50. Figure 3 It can be concluded that when the length of the concave region 60 in the Lamb wave propagation direction is greater than or equal to 0.3λ, the admittance clutter of the Lamb wave resonator is significantly reduced, and most clutter is suppressed. When the ratio of the length of the concave region 60 in the Lamb wave propagation direction to the wavelength of the Lamb wave is less than 0.3, the admittance clutter of the Lamb wave resonator is increased, thus affecting the energy loss and quality factor of the resonator. By setting the ratio of the length of the concave region 60 in the Lamb wave propagation direction to the wavelength of the Lamb wave to be greater than or equal to 0.3, the energy loss of the Lamb wave resonator can be reduced and the quality factor of the Lamb wave resonator can be improved.

[0027] Optionally, the thickness range of the dielectric layer 50 may vary depending on the material of the dielectric layer 50. The dielectric layer 50 is made of one of silicon oxide, silicon nitride, aluminum nitride, and aluminum oxide.

[0028] Specifically, the dielectric layer 50 is made of one of silicon oxide, silicon nitride, aluminum nitride, and aluminum oxide, which can achieve stray suppression and improve the quality factor of the Lamb wave resonator.

[0029] Optionally, when the material of the dielectric layer 50 is silicon oxide, the ratio of the thickness of the dielectric layer 50 to the thickness of the piezoelectric layer 30 is greater than or equal to 0.45 and less than or equal to 0.52. When the material of the dielectric layer 50 is silicon nitride, the ratio of the thickness of the dielectric layer 50 to the thickness of the piezoelectric layer 30 is greater than or equal to 0.22 and less than or equal to 0.43. When the material of the dielectric layer 50 is aluminum nitride, the ratio of the thickness of the dielectric layer 50 to the thickness of the piezoelectric layer 30 is greater than or equal to 0.35 and less than or equal to 0.43. When the material of the dielectric layer 50 is aluminum oxide, the ratio of the thickness of the dielectric layer 50 to the thickness of the piezoelectric layer 30 is greater than or equal to 0.43 and less than or equal to 0.52.

[0030] Specifically, Figure 6 This is a comparison chart of admittance-frequency curves for Lamb wave resonators with different ratios of dielectric layer thickness to piezoelectric layer thickness, provided as an embodiment of the present invention. Figure 7 A comparison of admittance-frequency curves for Lamb wave resonators with different ratios of dielectric layer thickness to piezoelectric layer thickness provided in this embodiment of the invention. Figure 8 A comparison of admittance-frequency curves for Lamb wave resonators with different ratios of dielectric layer thickness to piezoelectric layer thickness, provided in this embodiment of the invention. Figure 9 A comparison of admittance-frequency curves for Lamb wave resonators with different ratios of dielectric layer thickness to piezoelectric layer thickness, as provided in this embodiment of the invention, is shown in the reference diagram. Figure 2 , Figures 6-9 , Figure 6 The dielectric layer 50 of the middle Lamb wave resonator is made of silicon oxide, such as SiO2. Figure 6 As can be seen from the curve, when the ratio of the thickness of the dielectric layer 50 to the thickness of the piezoelectric layer 30 is greater than or equal to 0.45 and less than or equal to 0.52, the noise of the Lamb wave resonator is basically eliminated. Figure 7 The dielectric layer 50 of the Lamb wave resonator is made of silicon nitride, such as Si3N4. Figure 7 As can be seen from the curve, when the ratio of the thickness of the dielectric layer 50 to the thickness of the piezoelectric layer 30 is greater than or equal to 0.22 and less than or equal to 0.43, the noise of the Lamb wave resonator is basically eliminated. Figure 8 The dielectric layer 50 of the Lamb wave resonator is made of aluminum nitride, such as AlN. Figure 8 As can be seen from the curve, when the ratio of the thickness of the dielectric layer 50 to the thickness of the piezoelectric layer 30 is greater than or equal to 0.35 and less than or equal to 0.43, the noise of the Lamb wave resonator is basically eliminated. Figure 9 The dielectric layer 50 of the middle Lamb wave resonator is made of aluminum oxide, such as Al2O3. Figure 9 As can be seen from the curve, when the ratio of the thickness of the dielectric layer 50 to the thickness of the piezoelectric layer 30 is greater than or equal to 0.43 and less than or equal to 0.52, the noise of the Lamb wave resonator is basically eliminated.

[0031] Optionally, the ratio of the thickness of the first low acoustic impedance layer 21 to the thickness of the second low acoustic impedance layer 23 is greater than or equal to 2.

[0032] Specifically, Figure 10 The admittance-frequency curve of a Lamb wave resonator with a thickness ratio of the first low acoustic impedance layer to the second low acoustic impedance layer greater than or equal to 2, provided in an embodiment of the present invention. Figure 11 This is a schematic diagram of the Lamb wave resonator in the comparative embodiment. Figure 12 The admittance-frequency curve of the Lamb wave resonator in the comparative embodiment is shown. Figure 13 For comparison, here is an admittance-frequency curve comparison diagram of another Lamb wave resonator in the comparative embodiment, refer to... Figure 2 , Figures 10-13 , Figure 10The A3 mode represents the third antisymmetric Lamb wave mode, and the S2 mode represents the second symmetric Lamb wave mode. When the ratio of the thickness of the first low acoustic impedance layer 21 to the thickness of the second low acoustic impedance layer 23 is greater than or equal to 2, the noise of the Lamb wave resonator can be suppressed.

[0033] refer to Figure 11 In the comparative embodiment, the ratio of the thickness of the first low acoustic impedance layer 21 to the thickness of the second low acoustic impedance layer 23 is less than 2. When the material of the dielectric layer 50 is silicon oxide, the ratio of the thickness of the dielectric layer 50 to the thickness of the piezoelectric layer 30 is greater than or equal to 0 and less than or equal to 0.43. The remaining settings are the same as those of the Lamb wave resonator in the embodiment of the present invention. Figure 12 The A1 mode Lamb wave in the comparative embodiment is a first-order antisymmetric Lamb wave mode, which does not include the third-order antisymmetric Lamb wave mode and the second-order symmetric Lamb wave mode, and cannot suppress the clutter of the Lamb wave resonator. Figure 13 In this process, the dielectric layer 50 is made of silicon oxide, and the ratio of the thickness of the dielectric layer 50 to the thickness of the piezoelectric layer 30 is greater than or equal to 0. Figure 13 As can be seen from the comparative embodiment, the clutter of the Lamb resonator was not eliminated, which affected the energy loss and quality factor of the Lamb resonator.

[0034] Optionally, the Euler angle of the piezoelectric layer 30 is (0°, 0°, 90°), (0°, 38°, 0°), or (0°, 30°, 0°).

[0035] Specifically, the piezoelectric layer 30 is cut with a rotating ZY plane, so that the Euler angle of the piezoelectric layer 30 is (0°, 0°, 90°); the piezoelectric layer 30 is cut with a 120° Y plane, so that the Euler angle of the piezoelectric layer 30 is (0°, 38°, 0°); the piezoelectric layer 30 is cut with a 128° Y plane, so that the Euler angle of the piezoelectric layer 30 is (0°, 30°, 0°).

[0036] Optionally, the materials of the first low acoustic impedance layer 21 and the second low acoustic impedance layer 23 include silicon oxide; The high acoustic impedance layer 22 includes at least one of tantalum oxide, silicon nitride, aluminum nitride, silicon carbide, molybdenum, tungsten, gold, or platinum.

[0037] This configuration allows for a significant difference in acoustic impedance between the low acoustic impedance layer and the high acoustic impedance layer 22 in the acoustic Bragg reflector 20, resulting in stronger Bragg reflection and a wider sound-blocking band. This enhances the mechanical stability of the acoustic Bragg reflector 20, simplifies the wafer-level packaging process, and improves the manufacturing yield of the acoustic Bragg reflector 20.

[0038] Optionally, the Lamb wave includes a third-order antisymmetric Lamb wave mode and / or a second-order symmetric Lamb wave mode.

[0039] Specifically, the Lamb resonator in this embodiment of the invention can suppress clutter of the third-order antisymmetric Lamb mode and / or the second-order symmetric Lamb mode, reduce the energy loss of the Lamb resonator, and improve the quality factor of the Lamb resonator.

[0040] Continue to refer to Figure 1 Optionally, the Lamb wave resonator also includes a transmitter electrode 43 and a transmitter busbar 44. Along the electrode finger 41 arrangement direction of the interdigital transducer 40, the transmitter electrode 43 is symmetrically distributed on both sides of the interdigital transducer 40. Along the extension direction of the electrode fingers 41 of the interdigital transducer 40, the transmitter busbars 44 are symmetrically distributed on both sides of the transmitter electrode 43. The interdigital transducer 40 includes a first electrode finger 411, a second electrode finger 412, and an interdigital transducer busbar 42.

[0041] Specifically, the electrode fingers 41 of the interdigital transducer 40 are arranged in the X direction, and their extension direction is the Y direction. The first electrode fingers 411 and the second electrode fingers 412 are arranged alternately along the X direction. The interdigital transducer busbar 42 includes a first interdigital busbar and a second interdigital busbar, which are distributed along the Y direction on both sides of the first electrode fingers 411 and the second electrode fingers 412. The first interdigital busbar connects to the first electrode fingers 411, and the second interdigital busbar connects to the second electrode fingers 412. The transmitter busbar 44 connects to the transmitter electrode 43.

[0042] This invention provides a Lamb wave filter. Figure 14 This is a schematic diagram of a Lamb wave filter provided in an embodiment of the present invention, with reference to... Figure 14 The Lamb wave filter includes a series arm resonator 100 and a parallel arm resonator 200, at least one of the series arm resonator 100 and the parallel arm resonator 200 being any Lamb wave resonator 300 in the above embodiments.

[0043] Specifically, the Lamb wave filter includes a series arm resonator 100 and a parallel arm resonator 200. At least one of the series arm resonator 100 and the parallel arm resonator 200 is any Lamb wave resonator 300 in the above embodiments. The series arm resonator 100 and the parallel arm resonator 200 interact to suppress clutter in the Lamb wave filter, reduce the energy loss of the Lamb wave filter, and improve the quality factor of the Lamb wave filter.

[0044] The Lamb wave filter in this embodiment belongs to the same inventive concept as the Lamb wave resonator provided in any embodiment of the present invention, and has corresponding beneficial effects. For technical details not covered in this embodiment, please refer to the Lamb wave resonator described in any embodiment of the present invention.

[0045] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0046] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A Lamb wave resonator, characterized in that, include: Support substrate, acoustic Bragg reflector, piezoelectric layer, interdigital transducer and dielectric layer; The acoustic Bragg reflector is disposed on the first surface of the supporting substrate; The piezoelectric layer is disposed on the side of the acoustic Bragg reflector away from the supporting substrate; The interdigital transducer is disposed on the side of the piezoelectric layer away from the supporting substrate; The interdigital transducer includes multiple electrode fingers; The dielectric layer is disposed on the side of the interdigital transducer away from the supporting substrate, and the dielectric layer covers the electrode finger and a portion of the piezoelectric layer; Between two adjacent electrode fingers, a recessed region is formed between the piezoelectric layer, which is not covered by the dielectric layer, and the dielectric layer; The acoustic Bragg reflector includes a first low acoustic impedance layer and at least one group of impedance layers; The impedance layer group is disposed on the first surface of the support substrate, and the first low acoustic impedance layer is disposed on the side of the impedance layer group away from the support substrate. Each of the impedance layer groups includes a high acoustic impedance layer and a second low acoustic impedance layer that are alternately stacked along the thickness direction of the impedance layer group, wherein the high acoustic impedance layer is disposed on the side of the second low acoustic impedance layer away from the support substrate. The thickness of the first low acoustic impedance layer is greater than the thickness of the second low acoustic impedance layer.

2. The Lamb wave resonator according to claim 1, characterized in that: The ratio of the length of the recessed region in the direction of Lamb wave propagation to the wavelength of the Lamb wave is greater than or equal to 0.

3.

3. The Lamb wave resonator according to claim 1, characterized in that: The thickness range of the dielectric layer varies depending on the material. The dielectric layer is made of one of silicon oxide, silicon nitride, aluminum nitride, and aluminum oxide.

4. The Lamb wave resonator according to claim 3, characterized in that: When the dielectric layer is made of silicon oxide, the ratio of the thickness of the dielectric layer to the thickness of the piezoelectric layer is greater than or equal to 0.45 and less than or equal to 0.

52. When the dielectric layer is made of silicon nitride, the ratio of the thickness of the dielectric layer to the thickness of the piezoelectric layer is greater than or equal to 0.22 and less than or equal to 0.

43. When the dielectric layer is made of aluminum nitride, the ratio of the thickness of the dielectric layer to the thickness of the piezoelectric layer is greater than or equal to 0.35 and less than or equal to 0.

43. When the dielectric layer is made of aluminum oxide, the ratio of the thickness of the dielectric layer to the thickness of the piezoelectric layer is greater than or equal to 0.43 and less than or equal to 0.

52.

5. The Lamb wave resonator according to claim 1, characterized in that: The ratio of the thickness of the first low acoustic impedance layer to the thickness of the second low acoustic impedance layer is greater than or equal to 2.

6. The Lamb wave resonator according to claim 1, characterized in that: The Euler angle of the piezoelectric layer is (0°, 0°, 90°), (0°, 38°, 0°), or (0°, 30°, 0°).

7. The Lamb wave resonator according to claim 1, characterized in that: The materials of the first low acoustic impedance layer and the second low acoustic impedance layer include silicon oxide; The high acoustic impedance layer includes at least one of tantalum oxide, silicon nitride, aluminum nitride, silicon carbide, molybdenum, tungsten, gold, or platinum.

8. The Lamb wave resonator according to claim 1, characterized in that: Lamb waves include third-order antisymmetric Lamb wave modes and / or second-order symmetric Lamb wave modes.

9. The Lamb wave resonator according to claim 1, characterized in that, Also includes: The transmitter electrodes and transmitter busbar are arranged along the electrode finger arrangement direction of the interdigital transducer, and the transmitter electrodes are symmetrically distributed on both sides of the interdigital transducer; Along the extension direction of the electrode fingers of the interdigital transducer, the transmitter busbars are symmetrically distributed on both sides of the transmitter electrodes; The interdigital transducer includes a first electrode finger, a second electrode finger, and an interdigital transducer busbar.

10. A Lamb wave filter, characterized in that, It includes a series arm resonator and a parallel arm resonator, at least one of the series arm resonator and the parallel arm resonator being a Lamb wave resonator as described in any one of claims 1-9.

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