Elastic wave resonator, filter, and electronic device

Abstract

The utility model discloses an elastic wave resonator, a filter and electronic equipment, and belongs to the technical field of surface acoustic waves. The elastic wave resonator comprises a supporting layer, a piezoelectric layer and an interdigital transducer which are sequentially stacked, the interdigital transducer comprises a plurality of first electrode fingers, second electrode fingers and bus bars oppositely arranged in the first direction, and the first electrode fingers and the second electrode fingers extend in the first direction and are alternately arranged in the second direction; the intersection part of the first electrode fingers and the second electrode fingers forms an aperture area, and a gap area is formed between the aperture area and the bus bar; the first width of the first part of the first electrode finger in the gap area is larger than the second width of the second part in the aperture area, and the third width of the third part of the second electrode finger in the gap area is larger than the fourth width of the fourth part in the aperture area. The at least one first part and the at least one third part are provided with a load layer at one side close to the piezoelectric layer and / or one side far away from the piezoelectric layer, so that the generation of a transverse mode can be inhibited.

Description

Technical Field

[0001] This application belongs to the technical field of surface acoustic wave, and particularly relates to an elastic wave resonator, a filter and an electronic device. Background Art

[0002] In an elastic wave device excited by an interdigital transducer, the acoustic wave propagating transversely reflects at the boundary of the electrode fingers, which causes a transverse mode in the resonator. The existence of the transverse mode leads to ripples in the piezoelectric filter within the band and near the passband. These ripples increase the device loss and reduce the performance of the resonator and the filter. Summary of the Utility Model

[0003] This application aims to solve at least one of the technical problems existing in the prior art. For this purpose, this application provides an elastic wave resonator, a filter and an electronic device, in which the phase of the acoustic wave reflected at the boundary of the electrode fingers is changed, the conditions for generating the transverse mode are destroyed, thereby suppressing the generation of the transverse mode and improving the performance of the resonator.

[0004] In a first aspect, this application provides an elastic wave resonator, including: a support layer, a piezoelectric layer and an interdigital transducer stacked in sequence. The interdigital transducer includes a plurality of first electrode fingers, a plurality of second electrode fingers, and a first bus bar and a second bus bar arranged oppositely along a first direction. The first electrode fingers are connected to the first bus bar, the second electrode fingers are connected to the second bus bar, the first electrode fingers and the second electrode fingers extend along the first direction and are alternately arranged along a second direction. In the second direction, the cross portion of the first electrode fingers and the second electrode fingers forms a pore region, and a gap region is formed between the pore region and the bus bar. The first direction intersects with the second direction.

[0005] Wherein, a first width of a first portion of the first electrode finger located in the gap region is greater than a second width of a second portion of the first electrode finger located in the pore region, a third width of a third portion of the second electrode finger located in the gap region is greater than a fourth width of a fourth portion of the second electrode finger located in the pore region, and at least one first portion and at least one third portion are provided with a load layer on one side close to the piezoelectric layer and / or on one side far from the piezoelectric layer.

[0006] According to an embodiment of this application, the first width Wgap1 satisfies: W1 < Wgap1 < 3W1, and the third width Wgap2 satisfies: W2 < Wgap2 < 3W2, where W1 is the second width and W2 is the fourth width.

[0007] According to an embodiment of this application, in the second direction, the load layer is provided on the side of the first portion and the third portion far from the piezoelectric layer, and the width of the load layer is less than or equal to the width of the electrode finger laminated therewith.

[0008] According to one embodiment of this application, the first busbar includes a third electrode finger arranged along a second direction, and the second busbar includes a fourth electrode finger arranged along the second direction. The third electrode finger is arranged opposite to the second electrode finger, and the fourth electrode finger is arranged opposite to the first electrode finger. The third electrode finger and the fourth electrode finger form a pseudo-finger region, and the gap region is located between the pseudo-finger region and the aperture region.

[0009] According to one embodiment of this application, the fifth width of the fifth portion of the first electrode finger located in the pseudo-finger region is greater than the second width, the width of the sixth portion of the second electrode finger located in the pseudo-finger region is greater than the fourth width, and at least one fifth portion and at least one sixth portion are provided with a load layer on the side close to the piezoelectric layer and / or on the side far away from the piezoelectric layer.

[0010] According to one embodiment of this application, the length of the gap region along the first direction is 0.1λ to 2.5λ, where λ is the wavelength of the elastic wave.

[0011] According to one embodiment of this application, the load layer includes a metal layer and / or a dielectric layer.

[0012] According to one embodiment of this application, a load layer is disposed on the side of the first portion and the third portion away from the piezoelectric layer, and in a first direction, the length of the load layer is greater than or equal to half the length of the gap region.

[0013] According to one embodiment of this application, in a first direction, the length of the load layer is equal to the length of the gap region.

[0014] Secondly, this application provides a filter including at least one of the aforementioned elastic wave resonators.

[0015] Thirdly, this application provides an electronic device including the aforementioned filter.

[0016] According to several embodiments of the elastic wave resonator, filter, and electronic device of this application, the width of the portion of the first electrode finger and the second electrode finger located in the gap region is increased, and a load layer is provided on the portion of the first electrode finger and the second electrode finger located in the gap region. By utilizing the mass load effect, the sound velocity in the gap region is mismatched with the sound velocity in the aperture region, causing the phase of the sound wave reflected at the boundary of the electrode finger to change, thus disrupting the conditions for the generation of transverse modes, thereby suppressing the generation of transverse modes and improving the performance of the resonator.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0019] Figure 1 This is a schematic cross-sectional view of the elastic wave resonator provided in the embodiments of this application;

[0020] Figure 2 This is a schematic diagram of the structure of an elastic wave resonator in related technologies;

[0021] Figure 3 This is one of the structural schematic diagrams of the elastic wave resonator provided in the embodiments of this application;

[0022] Figure 4 yes Figure 3 A schematic diagram of the cross-section of the interdigital transducer of the elastic wave resonator along AA';

[0023] Figure 5 This is a simulation comparison of the admittance curves of elastic wave resonators in embodiments of this application and related technologies as a function of frequency.

[0024] Figure 6 This is a simulation comparison of the real part of the admittance curve of an elastic wave resonator in the embodiments of this application and related technologies as a function of frequency;

[0025] Figure 7 This is a second schematic diagram of the structure of the elastic wave resonator provided in the embodiments of this application;

[0026] Figure 8 yes Figure 7 A schematic diagram of the cross-section of the interdigital transducer of the elastic wave resonator along AA';

[0027] Figure 9 yes Figure 7 A schematic diagram showing the sound velocity distribution in different regions of the elastic wave resonator.

[0028] Figure 10 This is the third schematic diagram of the elastic wave resonator provided in the embodiments of this application;

[0029] Figure 11 yes Figure 10 A schematic diagram of the cross-section of the interdigital transducer of the elastic wave resonator along AA';

[0030] Figure 12 This is a curve showing the admittance as a function of frequency for different gap region lengths in embodiments of this application;

[0031] Figure 13 This is a curve showing the change of the real part of the admittance with frequency under different lengths of the gap region in the embodiments of this application.

[0032] Figure label:

[0033] Support layer 10, piezoelectric layer 20, interdigital transducer 30, first electrode finger 31, first part 311, second part 312, fifth part 313, first busbar 32, second electrode finger 33, third part 331, fourth part 332, sixth part 333, third electrode finger 34, second busbar 35, fourth electrode finger 36, load layer 40, gap region 50, aperture region 60, pseudo-finger region 70. Detailed Implementation

[0034] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0035] In the following description, a "circuit" refers to a conductive loop consisting of at least one element or sub-circuit connected by an electrical or electromagnetic link. When an element or circuit is said to be "coupled to" or "connected to" another element, or when an element / circuit is said to be "coupled at" or "connected at" two nodes, it can be directly coupled to or connected to the other element, or there may be intermediate elements. The connection between elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there are no intermediate elements between them.

[0036] In the description, the terms "first," "second," etc., are used to distinguish similar objects, not to describe a specific order or sequence. It should be understood that such numerical descriptors can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, not limited in number; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0037] Furthermore, the use of terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0038] With the continuous development and application of communication technology, the requirements for radio frequency components are becoming increasingly stringent. As an important component of filters, elastic wave resonators are also facing severe challenges.

[0039] Reference Figure 1 and Figure 2 , Figure 1 A cross-sectional structure of an elastic wave resonator is shown. Figure 2 The structure of an elastic wave resonator in the related art is shown. The elastic wave resonator includes a support layer 10, a piezoelectric layer 20, and an interdigital transducer 30 stacked sequentially. A gap region 50 is formed between the electrode fingers in the interdigital transducer 30 and the busbar opposite them. In an elastic wave device excited by the interdigital transducer 30, the reflection of the transversely propagating sound wave in the gap region 50 causes the resonator to have a transverse mode. The presence of the transverse mode causes ripple in the band and near the passband of the piezoelectric filter. These ripples increase device losses and reduce the performance of the resonator and the filter.

[0040] Reference Figure 3 and Figure 4 , Figure 3 The structure of the elastic wave resonator according to an embodiment of this application is shown. Figure 4 It shows Figure 3 The cross-section of the interdigital transducer 30 of the elastic wave resonator is shown. One embodiment of this application proposes an elastic wave resonator comprising: a support layer 10, a piezoelectric layer 20, and an interdigital transducer 30 stacked sequentially. The interdigital transducer 30 includes a plurality of first electrode fingers 31, a plurality of second electrode fingers 33, and a first busbar 32 and a second busbar 35 arranged opposite each other along a first direction. The first electrode fingers 31 are connected to the first busbar 32, and the second electrode fingers 33 are connected to the second busbar 35. The first electrode fingers 31 and the second electrode fingers 33 extend along the first direction and are alternately arranged along a second direction. In the second direction, the intersection of the first electrode fingers 31 and the second electrode fingers 33 forms an aperture region 60. The aperture region 60 and the busbar... A gap region 50 is formed between the two, and the first direction intersects the second direction; wherein, the first width Wgap1 of the first part 311 of the first electrode finger 31 located in the gap region 50 is greater than the second width W2 of the second part 312 of the first electrode finger 31 located in the aperture region 60, and the third width Wgap3 of the third part 331 of the second electrode finger 33 located in the gap region 50 is greater than the fourth width W4 of the fourth part 332 of the second electrode finger 33 located in the aperture region 60, and at least one first part 311 and at least one third part 331 are provided with a load layer 40 on the side close to the piezoelectric layer 20 and / or on the side away from the piezoelectric layer 20.

[0041] In this application, the first direction refers to the Y direction shown in the figure, and the second direction refers to the X direction shown in the figure.

[0042] The support layer 10 primarily supports the main structure of the entire elastic wave resonator, ensuring that the resonator is not easily damaged by external stress and providing necessary strength and protection. The support layer 10 is typically formed of a material with high hardness. The specific material and thickness of the support layer 10 can be selected based on the actual application scenario and are not limited here. For example, the support layer 10 can be made of silicon, silicon nitride, silicon carbide, aluminum nitride, sapphire, spinel, or quartz. The thickness of the support layer 10 can be 0.01λ to 0.5λ, where λ is the wavelength of the elastic wave.

[0043] The piezoelectric layer 20 is the core component of the resonator, enabling it to function. When the frequency of the applied electrical signal matches the resonator's natural frequency, the material in the piezoelectric layer 20 deforms, generating mechanical vibration. This mechanical vibration further interacts with the electrical signal, achieving resonant amplification of the elastic wave. The material of the piezoelectric layer 20 typically possesses high mechanical strength and stiffness to withstand external forces and maintain structural stability, while also maintaining stable piezoelectric properties within a certain temperature range. The specific material and thickness of the piezoelectric layer 20 can be selected based on the actual application scenario and are not limited here. For example, the piezoelectric layer 20 can be made of silicon dioxide, aluminum nitride, zinc oxide, lead zirconate titanate piezoelectric ceramics, polyvinylidene fluoride, or lithium tantalate, etc. The thickness of the piezoelectric layer 20 can range from 0.01λ to 0.5λ.

[0044] The interdigital transducer 30 can be composed of one or more of titanium, nickel, molybdenum, copper, tungsten, gold, silver, aluminum, and platinum, and is mainly used to realize the mutual conversion between acoustic signals and electrical signals. The thickness of the interdigital transducer 30 can be selected according to the actual application scenario and is not limited here. For example, the thickness of the interdigital transducer 30 can be 0.01λ to 0.15λ.

[0045] The aperture region 60 refers to the area formed by the intersection of the first electrode finger 31 and the second electrode finger 33. The gap region 50 refers to the area between the aperture region 60 and the first busbar 32, and the area between the aperture region 60 and the second busbar 35.

[0046] The width of the portions of the first electrode finger 31 and the second electrode finger 33 located in the gap region 50 is greater than the width of the portions of the first electrode finger 31 and the second electrode finger 33 located in the aperture region 60, which can increase the duty ratio of the metal in the gap region 50, such that the unit mass of the first electrode finger 31 and the second electrode finger 33 in the gap region 50 is greater than the unit mass of the first electrode finger 31 and the second electrode finger 33 in the aperture region 60. In the gap region 50, the load layer 40 is stacked with the first portion 311 and the third portion 33, and can be disposed either above the first portion 311 and the third portion 331 or below the first portion 311 and the third portion 331. Depositing the load layer 40 in the stacking direction of the electrode fingers can also increase the mass of the portions of the first electrode finger 31 and the second electrode finger 33 located in the gap region 50 to a certain extent.

[0047] The portions of the first electrode finger 31 and the second electrode finger 33 located in the gap region 50 are widened, and a load layer is provided on the widened electrode fingers, which can enable more load layers to be deposited on the electrode fingers located in the gap region 50, thereby further increasing the mass of the electrode fingers in the gap region 50.

[0048] It should be noted that the width of the load layer can be set according to the actual application scenario and is not limited herein. The width of the load layer can be greater than the width of the electrode fingers in the gap region 50, or can be less than or equal to the width of the electrode fingers in the gap region 50.

[0049] The number of electrode fingers in the gap region 50 is half of the number of electrode fingers in the aperture region 60. Therefore, the sound wave propagation speed in the gap region 50 is generally much greater than that in the aperture region 60. By increasing the width of the portions of the first electrode finger 31 and the second electrode finger 33 located in the gap region 50 and providing the load layer 40 on at least one of the first electrode finger 31 and at least one of the second electrode finger 33 located in the gap region 50 in the embodiments of the present application, the sound wave propagation speed in the gap region 50 can be reduced, the sound wave phase of the laterally propagating sound wave in the gap region 50 can be changed, and the sound wave phase can satisfy the waveguide condition to suppress the generation of the lateral mode.

[0050] It should be noted that the embodiments of the present application can reduce the sound wave propagation speed Vgap in the gap region 50 to satisfy: 0.9V0 < Vgap < V0, V0 < Vgap < 1.1V0, where V0 is the sound wave propagation speed in the aperture region 60, so as to achieve a better effect of suppressing the transverse wave.

[0051] The load layer 40 is mainly used to increase the mass of the first electrode finger 31 and the second electrode finger 33 in the gap region 50. The specific material of the load layer 40 can be selected according to the actual application scenario and is not limited herein. For example, the load layer 40 can be alumina or platinum, etc.

[0052] It should be noted that the first electrode fingers 31 and the second electrode fingers 33 corresponding to the gap region 50 in the load layer 40 are arranged in a stacked manner. The load layer 40 may cover all the portions of the first electrode fingers 31 and the second electrode fingers 33 located within the gap region 50, or may cover any number of the portions of the first electrode fingers 31 and the second electrode fingers 33 located within the gap region 50. For example, the interdigital transducer 30 includes 10 first electrode fingers 31 and 10 second electrode fingers 33, and the load layer 40 may cover the portions of 5 first electrode fingers 31 and 5 second electrode fingers 33 located in the gap region 50.

[0053] For one electrode finger, the load layer 40 may cover all the portions of the electrode finger corresponding to the gap region 50, or may cover a partial region of the electrode finger located within the gap region 50. For example, the partial length of one electrode finger located in the gap region 50 is 2λ, and the width of the electrode finger is also 2λ. The load layer 40 is disposed on the side of the electrode finger away from the piezoelectric layer 20. The length of the load layer 40 may be 2λ, and the width may also be 2λ; or the length of the load layer 40 may be λ, and the width may also be λ.

[0054] The load layer 40 may be disposed on the side of the first portion 311 and the third portion 331 close to the piezoelectric layer 20, or may be disposed on the side of the first portion 311 and the third portion 331 away from the piezoelectric layer 20, or may be disposed on both the side of the first portion 311 and the third portion 331 close to the piezoelectric layer 20 and the side away from the piezoelectric layer 20. The specific range covered by the load layer 40 may be selected according to the actual application scenario, and is not limited herein.

[0055] According to the elastic wave resonator of the present application, the widths of the portions of the first electrode fingers 31 and the second electrode fingers 33 located in the gap region 50 are increased, and a load layer 40 is disposed on the portions of the first electrode fingers 31 and the second electrode fingers 33 located in the gap region 50. By using the mass loading effect, the sound velocity in the gap region 50 is made not to match the sound velocity in the aperture region 60, so that the phase of the sound wave reflected at the boundary of the electrode fingers is changed, the conditions for generating the transverse mode are destroyed, and thus the generation of the transverse mode is suppressed, improving the performance of the resonator.

[0056] In some embodiments, the first width Wgap1 satisfies: W1 < Wgap1 < 3W1, and the third width Wgap2 satisfies: W2 < Wgap2 < 3W2, where W1 is the second width and W2 is the fourth width.

[0057] The first width Wgap1 of the first part 311 is greater than the second width W1 of the second part 312, and the third width Wgap2 of the third part 331 is greater than the fourth width W2 of the fourth part 332. This can increase the duty cycle of the metal in the gap region 50, that is, increase the mass of the portions of the first electrode fingers 31 and the second electrode fingers 33 located in the gap region 50, reduce the sound wave propagation speed in the gap region 50, change the sound wave phase of the laterally propagating sound wave in the gap region 50, and make the sound wave phase satisfy the waveguide condition to suppress the generation of the transverse mode. When Wgap1 < 3W1 and Wgap2 < 3W2 in the gap region 50, it can avoid the decrease of the resonance frequency caused by the over-wide electrode fingers and reduce the transducer efficiency.

[0058] In summary, the first width Wgap1 satisfies: W1 < Wgap1 < 3W1, and the third width Wgap2 satisfies: W2 < Wgap2 < 3W2. This can not only suppress the generation of the transverse mode but also ensure the best energy conversion efficiency between the electric field and the sound wave.

[0059] In some embodiments, the interdigital transducer 30 is made of aluminum, the thickness of the interdigital transducer 30 is 160 nm, the piezoelectric layer 20 is made of lithium tantalate, the thickness of the piezoelectric layer 20 is 530 nm, the support layer 10 is made of silicon and silicon dioxide, the length of the aperture region 60 is 20λ, and a load layer 40 is provided on the electrode fingers of the interdigital transducer 30 corresponding to the gap region 50, and the thickness of the load layer 40 is 100 nm.

[0060] Referring to Figure 5 and Figure 6 , Figure 5 shows a simulation comparison diagram of the admittance of the elastic wave resonator in the above embodiment when Wgap = 2W0 and that of the related art varying with frequency. Figure 6 shows a simulation comparison diagram of the real part of the admittance of the elastic wave resonator in the above embodiment when Wgap = 2W0 and that of the related art varying with frequency, and the real part of the admittance. Here, Wgap is the width of the electrode fingers in the gap region 50, and W0 is the width of the electrode fingers in the aperture region 60. Figure 5 In Figure 6 , curve (1) represents the curve of the admittance of the elastic wave resonator in the related art varying with frequency, and curve (2) represents the curve of the admittance of the elastic wave resonator in the embodiment of the present application varying with frequency. Figure 5 In Figure 6It is understood that the right side of the resonance peak of the real part of the admittance curve of the elastic wave resonator in the embodiment of this application is smoother than the right side of the resonance peak of the real part of the admittance curve of the elastic wave resonator in the related art. That is, the embodiment of this application can effectively reduce the intensity of the transverse mode of the elastic wave resonator.

[0061] In some embodiments, the load layer 40 is disposed on the side of the first portion 311 and the third portion 331 away from the piezoelectric layer 20, and the width of the load layer 40 is less than or equal to the width of the electrode finger stacked therewith.

[0062] The load layer 40 can be deposited on the side of the first part 311 and the third part 331 away from the piezoelectric layer 20, which facilitates the fabrication process. The width of the load layer 40 is less than or equal to the width of the electrode finger stacked with it, which can avoid the load layer 40 being deposited on the piezoelectric layer 20 and affecting the energy conversion efficiency of the elastic wave resonator.

[0063] Reference Figure 7 and Figure 8 , Figure 7 The structure of the elastic wave resonator according to an embodiment of this application is shown. Figure 8 It shows Figure 7 The cross-section of the interdigital transducer 30 of the elastic wave resonator is shown. In some embodiments, the first busbar 32 includes a third electrode finger 34 arranged along a second direction, and the second busbar 35 includes a fourth electrode finger 36 arranged along the second direction. The third electrode finger 34 is arranged opposite to the second electrode finger 33, and the fourth electrode finger 36 is arranged opposite to the first electrode finger 31. The third electrode finger 34 and the fourth electrode finger 36 form a pseudo-finger region 70, and the gap region 50 is located between the pseudo-finger region 70 and the aperture region 60.

[0064] The third electrode finger 34 and the fourth electrode finger 36 are dummy fingers. The busbar is designed to include the dummy fingers, which can reduce the propagation speed of sound waves in the gap region 50 to a certain extent.

[0065] For an elastic wave resonator with a pseudofinger, a load layer 40 is provided on the first electrode finger 31 and the second electrode finger 33 corresponding to the gap region 50 between the pseudofinger region 70 and the aperture region 60. This can further reduce the propagation speed of the sound wave in the gap region 50 and better suppress the generation of transverse modes.

[0066] Reference Figure 9 , Figure 9 A schematic diagram of the sound velocity distribution in each region of this embodiment is shown. Figure 9 It can be seen that the sound velocity in the gap region 50 is Vgap≈1.05V0, which satisfies V0<Vgap<1.1V0. This can change the phase of the reflection of the transverse sound wave propagating from the aperture region 60 to the gap region at the boundary between the aperture and the gap region, thus disrupting the conditions for the generation of the transverse mode.

[0067] Reference Figure 10 and Figure 11 , Figure 10 The structure of the elastic wave resonator according to an embodiment of this application is shown. Figure 11 It shows Figure 10 The cross-section of the interdigital transducer 30 of the elastic wave resonator is shown. In some embodiments, the fifth width of the fifth portion 313 of the first electrode finger 31 located in the pseudo-finger region 70 is greater than the second width, the width of the sixth portion 333 of the second electrode finger 33 located in the pseudo-finger region 70 is greater than the fourth width, and at least one fifth portion 313 and at least one sixth portion 333 are provided with a load layer 40 on the side closer to the piezoelectric layer and / or on the side farther away from the piezoelectric layer.

[0068] The load layer 40 is disposed on the portion of the first electrode finger 31 and the second electrode finger 33 located in the pseudo-finger region 70. It can also alter the propagation speed of sound waves within the gap region 50 and the pseudo-finger region 70, causing a mismatch between the sound velocity in the gap region 50 and the pseudo-finger region 70 and the sound velocity in the aperture region 60. This alters the phase of the sound wave reflection at the boundary of the electrode finger, disrupting the conditions for transverse mode generation and thus suppressing the generation of transverse modes. The arrangement of the load layer 40 on the first portion 311, the third portion 331, the fifth portion 313, and the sixth portion 333 can be selected according to the actual application scenario and is not limited here.

[0069] As an example, a load layer 40 is provided on the side of the first part 311, the third part 331, the fifth part 313 and the sixth part 333 away from the piezoelectric layer 20.

[0070] As another example, the first part 311 and the third part 331 are provided with a load layer 40 on the side away from the piezoelectric layer 20, and the fifth part 313 and the sixth part 333 are provided with load layers 40 at intervals along the second direction on the side away from the piezoelectric layer 20.

[0071] Reference Figure 12 and Figure 13 , Figure 12 The following diagram shows the admittance versus frequency curves for different lengths of the gap region 50 of the elastic wave resonator according to embodiments of this application. Figure 13 The diagram illustrates the real part of the admittance as a function of frequency for an elastic wave resonator according to an embodiment of this application, with varying lengths of the gap region 50. In some embodiments, the length of the gap region 50 along the first direction is 0.1λ to 2.5λ, where λ is the wavelength of the elastic wave.

[0072] The length of the gap region 50 determines the propagation path and time of the sound wave within it. A longer gap increases the phase delay of the sound wave, which may cause the phase difference between the reflected wave and the aperture region 60 to reach a certain condition, thus leading to the generation of transverse modes. Therefore, adjusting the length of the gap region 50 can effectively control the reflected phase difference and reduce the interference of transverse modes.

[0073] Figure 12 Curve (5) shows the admittance versus frequency when the length of the gap region of the elastic wave resonator is λ in the relevant technology. Figure 12 It can be seen that when the length of the gap region 50 is in the range of 0.1λ to 2.5λ, the right side of the resonance peak of the admittance curve of the elastic wave resonator of this application is smoother than the right side of the resonance peak of the admittance curve of the elastic wave resonator in the related art. Figure 13 Curve (6) is a curve showing the real part of the admittance as a function of frequency when the length of the gap region of the elastic wave resonator is λ in the relevant technology. Figure 13 It can be seen that when the length of the gap region 50 is in the range of 0.1λ to 2.5λ, the right side of the resonance peak of the real part of the admittance curve of the elastic wave resonator of this application is smoother than the right side of the resonance peak of the real part of the admittance curve of the elastic wave resonator in the related art. In summary, the length of the gap region 50 along the first direction of 0.1λ to 2.5λ can effectively reduce the intensity of the transverse mode of the elastic wave resonator.

[0074] In some embodiments, the load layer 40 includes a metal layer and / or a dielectric layer.

[0075] The metal layer can be disposed on the side of the first portion 311 and the third portion 331 closest to the piezoelectric layer 20, or on the side of the first portion 311 and the third portion 331 furthest from the piezoelectric layer 20. Similarly, the dielectric layer can be disposed on the side of the first portion 311 and the third portion 331 closest to the piezoelectric layer 20, or on the side of the first portion 311 and the third portion 331 furthest from the piezoelectric layer 20. The specific arrangement of the metal layer and the dielectric layer can be selected according to the actual application scenario, and is not limited here.

[0076] As an example, a dielectric layer is provided on the side of the first portion 311 and the third portion 331 near the piezoelectric layer 20, and a metal layer is provided on the side of the first portion 311 and the third portion 331 away from the piezoelectric layer 20.

[0077] As another example, a metal layer and a dielectric layer are stacked sequentially on the side of the first part 311 and the third part 331 away from the piezoelectric layer 20.

[0078] The dielectric and metal layers are primarily used to increase the mass of the first electrode finger 31 and the second electrode finger 33 within the gap region 50. The specific materials of the dielectric and metal layers can be selected based on the actual application scenario and are not limited here. For example, the dielectric layer can be alumina, silicon dioxide, or silicon nitride, etc. The metal layer can be gold, silver, aluminum, or platinum, etc.

[0079] In some embodiments, the load layer 40 is disposed on the side of the first portion 311 and the third portion 331 away from the piezoelectric layer 20, and in the first direction, the length of the load layer 40 is greater than or equal to half the length of the gap region 50.

[0080] When the length of the load layer 40 is less than the length of the gap region 50, the load layer 40 can be set close to the root of the first electrode finger 31 and the second electrode finger 33 corresponding to the gap region 50, or it can be set away from the root of the first electrode finger 31 and the second electrode finger 33 corresponding to the gap region 50, or it can be set in the middle range of the first electrode finger 31 and the second electrode finger 33 corresponding to the gap region 50.

[0081] As an example, the gap region 50 has a length of 2λ, and the load layer 40 can be set within the λ length range of the first electrode finger 31 near the first busbar 32, or it can be set within the λ length range of the first electrode finger 31 near the second busbar 35.

[0082] Given a fixed material and width for the load layer 40, the greater the length of the load layer 40, the greater its mass. A load layer 40 that is greater than or equal to half the length of the gap region 50 can significantly improve the mass of the first electrode finger 31 and the second electrode finger 33, thereby effectively disrupting the conditions for the generation of transverse modes, suppressing the generation of transverse modes, and improving the performance of the resonator.

[0083] In some embodiments, the length of the load layer 40 is less than the length of the gap region 50, the load layer 40 is disposed on the side of the gap region 50 away from the busbar, and a preset distance is provided between the end of the load layer 40 near the busbar and the busbar.

[0084] When the length of the load layer 40 is less than the length of the gap region 50, the load layer 40 may or may not contact the busbar. The specific length of the preset distance between the load layer 40 and the busbar can be selected according to the actual application scenario, and is not limited here.

[0085] As an example, the preset distance is half of the gap region 50, that is, the length of the gap region 50 is 2λ, and the load layer 40 is set within the gap region at a length of λ away from the busbar, and the load layer 40 does not contact the busbar.

[0086] In other embodiments, the length of the load layer 40 is less than the length of the gap region 50, and the load layer 40 is disposed on the side of the gap region 50 near the busbar.

[0087] As another example, the gap region 50 has a length of 2λ, and the load layer 40 is disposed within the gap region near the busbar within a length of λ, with the load layer 40 in contact with the busbar.

[0088] In some embodiments, in the first direction, the length of the load layer 40 is equal to the length of the gap region 50.

[0089] The load layer 40 covers the entire gap region 50 in the first direction, which can increase the mass of the first electrode finger 31 and the second electrode finger 33 in the gap region 50 to a greater extent, thereby reducing the speed of sound wave propagation in the gap region 50 and suppressing the generation of transverse modes, and also facilitates the manufacturing process.

[0090] One embodiment of this application provides a filter including at least one of the aforementioned elastic wave resonators.

[0091] The specific structure and function of the elastic wave resonator can be referred to the aforementioned embodiments, and will not be repeated here.

[0092] According to the filter of this application, the width of the portion of the first electrode finger 31 and the second electrode finger 33 located in the gap region 50 is increased in the elastic wave resonator, and a load layer 40 is provided on the portion of the first electrode finger 31 and the second electrode finger 33 located in the gap region 50. By utilizing the mass loading effect, the sound velocity in the gap region 50 is mismatched with the sound velocity in the aperture region 60, which causes the phase of the sound wave reflected at the boundary of the electrode finger to change, thereby disrupting the conditions for the generation of transverse modes, suppressing the generation of transverse modes, and improving the performance of the resonator.

[0093] One embodiment of this application provides an electronic device including the aforementioned filter.

[0094] The filter includes at least one elastic wave resonator, which precisely selects a specific frequency band of the signal by choosing the resonant frequency, filters out unnecessary frequencies, and ensures that only signals of specific frequencies can pass through, thereby improving the signal quality of the communication system.

[0095] The specific structure and function of the elastic wave resonator can be referred to the aforementioned embodiments, and will not be repeated here.

[0096] According to the electronic device of this application, the width of the portion of the first electrode finger 31 and the second electrode finger 33 located in the gap region 50 is increased in the elastic wave resonator, and a load layer 40 is provided on the portion of the first electrode finger 31 and the second electrode finger 33 located in the gap region 50. By utilizing the mass load effect, the sound velocity in the gap region 50 is mismatched with the sound velocity in the aperture region 60, which causes the phase of the sound wave reflected at the boundary of the electrode finger to change, thereby disrupting the conditions for the generation of transverse modes, suppressing the generation of transverse modes, and improving the performance of the resonator.

[0097] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. An elastic wave resonator, characterized by, The piezoelectric layer and the interdigital transducer are sequentially stacked on the support layer, the interdigital transducer comprises a plurality of first electrode fingers, a plurality of second electrode fingers, and a first bus bar and a second bus bar oppositely arranged along a first direction, the first electrode fingers are connected with the first bus bar, the second electrode fingers are connected with the second bus bar, the first electrode fingers and the second electrode fingers extend along the first direction and are alternately arranged along a second direction, in the second direction, the first electrode fingers and the second electrode fingers form an aperture region at the intersection, and a gap region is formed between the aperture region and the bus bar, and the first direction intersects the second direction. The first width of a first part of the first electrode fingers in the gap region is greater than the second width of a second part of the first electrode fingers in the aperture region, the third width of a third part of the second electrode fingers in the gap region is greater than the fourth width of a fourth part of the second electrode fingers in the aperture region, and at least one of the first part and the third part is provided with a load layer on a side close to the piezoelectric layer and / or a side away from the piezoelectric layer.

2. The elastic wave resonator according to claim 1, characterized by, The first width Wgap1 satisfies W1 < Wgap1 < 3W1, and the third width Wgap2 satisfies W2 < Wgap2 < 3W2, wherein W1 is the second width, and W2 is the fourth width.

3. The elastic wave resonator according to claim 2, characterized by, In the second direction, the load layer is arranged on the side away from the piezoelectric layer of the first part and the third part, and the width of the load layer is less than or equal to the width of the electrode fingers stacked thereon.

4. The elastic wave resonator according to any one of Claims 1-3, wherein, The first bus bar comprises third electrode fingers arranged along the second direction, the second bus bar comprises fourth electrode fingers arranged along the second direction, the third electrode fingers are oppositely arranged with the second electrode fingers, the fourth electrode fingers are oppositely arranged with the first electrode fingers, the third electrode fingers and the fourth electrode fingers form a dummy finger region, and the gap region is located between the dummy finger region and the aperture region.

5. The elastic wave resonator according to claim 4, characterized in that, The fifth width of a fifth part of the first electrode fingers in the dummy finger region is greater than the second width, the width of a sixth part of the second electrode fingers in the dummy finger region is greater than the fourth width, and at least one of the fifth part and the sixth part is provided with the load layer on a side close to the piezoelectric layer and / or a side away from the piezoelectric layer.

6. The elastic wave resonator according to any one of Claims 1-3, wherein The length of the gap region along the first direction is 0.1λ-2.5λ, and λ is the wavelength of the elastic wave.

7. The elastic wave resonator according to any one of Claims 1-3, wherein The load layer comprises a metal layer and / or a dielectric layer.

8. The elastic wave resonator according to any one of Claims 1-3, wherein, The load layer is arranged on the side away from the piezoelectric layer of the first part and the third part, and in the first direction, the length of the load layer is less than or equal to the length of the gap region.

9. The elastic wave resonator of claim 8, wherein, In the first direction, the length of the load layer is less than the length of the gap region, the load layer is arranged on the side away from the bus bar of the gap region, and a preset distance is arranged between an end of the load layer close to the bus bar and the bus bar.

10. A filter, characterized by, An elastic wave resonator comprising at least one elastic wave resonator according to any one of claims 1-9.

11. An electronic device, comprising: A filter comprising the elastic wave resonator according to claim 10.

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