CN116232268A

CN116232268A - Elastic wave device, filter, and electronic apparatus

Info

Publication number: CN116232268A
Application number: CN202310094514.7A
Authority: CN
Inventors: 杜波; 王华磊; 倪建兴
Original assignee: Ruishi Chuangxin Chongqing Technology Co ltd
Current assignee: Ruishi Chuangxin Chongqing Technology Co ltd
Priority date: 2023-02-07
Filing date: 2023-02-07
Publication date: 2023-06-06

Abstract

The application provides an elastic wave device, which comprises a piezoelectric layer, an interdigital transducer and a reflecting structure. The interdigital transducer comprises two bus bars and a plurality of electrode fingers, one end of each electrode finger is connected with one bus bar, the other end of each electrode finger extends to the other bus bar, and the plurality of electrode fingers connected with the two bus bars are sequentially arranged at intervals in the sound wave propagation direction to form an alternating region. The elastic wave device further comprises a temperature compensation layer and a quality layer, wherein the temperature compensation layer is arranged on one side of the piezoelectric layer, provided with the interdigital transducer, and at least covers an alternating region of the interdigital transducer, the quality layer is arranged on one side of the temperature compensation layer, which is opposite to the interdigital transducer, and is positioned in the alternating region, and the quality layer is used for reducing sound velocity of sound waves corresponding to the alternating region. Under the condition of realizing the same resonant frequency, the elastic wave device can reduce the size of the interdigital transducer, thereby realizing the miniaturization design of the elastic wave device. The application also provides a filter and electronic equipment.

Description

Elastic wave device, filter, and electronic apparatus

Technical Field

The present disclosure relates to the field of radio frequency technologies, and in particular, to an elastic wave device, a filter with the elastic wave device, and an electronic device with the filter.

Background

The elastic wave device processes the sound wave propagated on the surface of the piezoelectric layer by utilizing the characteristics of the acoustic-electric transducer, and has the advantages of low cost, small volume, multiple functions and the like, so that the elastic wave device is widely applied to the fields of radar, communication, navigation, identification and the like.

The elastic wave device comprises an interdigital transducer, the interdigital transducer comprises a bus bar and a plurality of electrode fingers, the electrode fingers are connected with the bus bar in an electric connection mode, and the electrode fingers and the piezoelectric layer are matched to convert an electric signal into an acoustic wave or convert the acoustic wave into the electric signal. With the gradual miniaturization of electronic devices to which the elastic wave device is applied, the size of the existing elastic wave device is not conducive to achieving miniaturization of the electronic devices.

Therefore, miniaturization of the elastic wave device is a problem to be solved.

Disclosure of Invention

In view of the above-described drawbacks of the related art, an object of the present application is to provide an elastic wave device, a filter having the elastic wave device, and an electronic apparatus having the filter, which aim to achieve a miniaturized design of the elastic wave device.

In order to solve the above technical problems, an embodiment of the present application provides an elastic wave device, which includes a piezoelectric layer, an interdigital transducer located on the piezoelectric layer, and reflective structures disposed on two opposite sides of the interdigital transducer. The interdigital transducer comprises two bus bars and a plurality of electrode fingers which are oppositely arranged, one end of each electrode finger is connected with one bus bar, the other end of each electrode finger extends to the other bus bar, and the plurality of electrode fingers connected with the two bus bars are sequentially arranged at intervals in the sound wave propagation direction to form an alternating region. The elastic wave device further comprises a temperature compensation layer and a quality layer, wherein the temperature compensation layer is arranged on one side of the piezoelectric layer, provided with the interdigital transducer, and at least covers the alternating region of the interdigital transducer, and the quality layer is arranged on one side of the temperature compensation layer, which is opposite to the interdigital transducer, and is positioned in the alternating region.

In summary, in the elastic wave device provided in the embodiment of the present application, the mass layer is disposed in the alternating region of the interdigital transducer, so as to reduce the propagation speed of the acoustic wave in the alternating region, so that the required electrode finger period is reduced compared with the existing electrode finger period when the same resonant frequency is achieved, thereby reducing the size of the interdigital transducer in the process, and realizing the miniaturized design of the elastic wave device.

In an exemplary embodiment, the alternating regions include a middle region and edge regions located on both sides of the middle region. The elastic wave device further comprises a mass loading structure, wherein the mass loading structure is positioned at the edge area in a top view direction.

In an exemplary embodiment, the mass loading structure is disposed on a side of the mass layer facing the temperature compensation layer; or, the mass loading structure is arranged on the side of the mass layer opposite to the temperature compensation layer.

In an exemplary embodiment, the mass loading structure includes a plurality of mass loading blocks, the plurality of mass loading blocks are sequentially spaced in an arrangement direction of the plurality of electrode fingers, and at least a portion of the electrode fingers overlap at least one mass loading block in a top view direction.

In an exemplary embodiment, the mass-loading structure overlaps with a plurality of the electrode fingers 33 and a gap between adjacent two of the electrode fingers 33.

In an exemplary embodiment, the mass layer has a density greater than 4.5g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the And/or the mass loading structure has a density greater than 4.5g/cm ³ 。

In an exemplary embodiment, the material of the mass layer includes at least one of aluminum, copper, tungsten, molybdenum, gold, silver, platinum, and chromium; and/or the material of the mass-loaded structure comprises at least one of aluminum, copper, tungsten, molybdenum, gold, silver, platinum and chromium.

In an exemplary embodiment, the mass layer includes a metal film or a plurality of metal films stacked in order; and/or the mass loading structure comprises a layer of metal film or a plurality of layers of metal films which are sequentially stacked.

In an exemplary embodiment, the interdigital transducer further comprises a gap region adjacent to a side of the edge region opposite the intermediate region; the elastic wave device further comprises a high sound velocity layer, wherein the high sound velocity layer is at least arranged in the gap area, and the high sound velocity layer is configured to increase sound velocity corresponding to the area where the high sound velocity layer is located.

In an exemplary embodiment, the elastic wave device further includes a side region adjacent to a side of the gap region opposite to the edge region, and at least a portion of the bus bar is located in the side region, wherein a sound velocity corresponding to the side region is greater than a sound velocity corresponding to the middle region.

In an exemplary embodiment, the high acoustic velocity layer is disposed in the gap region and the side region.

In an exemplary embodiment, the material of the high acoustic velocity layer includes any one or more of silicon nitride, aluminum oxide, and silicon carbide.

In an exemplary embodiment, the length of the gap region is less than or equal to λ in the electrode finger extension direction, where λ is the period of the electrode finger.

In an exemplary embodiment, the length of the gap region in the electrode finger extension direction is less than or equal to 0.5λ, where λ is the period of the electrode finger.

In an exemplary embodiment, the length of the gap region in the electrode finger extension direction is less than or equal to 0.25 λ, where λ is the period of the electrode finger.

Based on the same inventive concept, embodiments of the present application also provide an elastic wave device including a piezoelectric layer, an interdigital transducer, and a reflective structure. The interdigital transducer comprises two bus bars and a plurality of electrode fingers which are oppositely arranged, one end of each electrode finger is connected with one bus bar, the other end of each electrode finger extends to the other bus bar, the plurality of electrode fingers connected with the two bus bars are sequentially arranged at intervals in the sound wave propagation direction to form an alternating region, and the alternating region comprises a middle region and edge regions positioned at two sides of the middle region. The elastic wave device further comprises a temperature compensation layer and a mass layer, wherein the temperature compensation layer is arranged on one side of the piezoelectric layer, provided with the interdigital transducer, and at least covers the alternating region of the interdigital transducer, the mass layer is arranged on one side of the temperature compensation layer, which is opposite to the interdigital transducer, and is positioned in the alternating region, and the mass layer is configured to reduce sound velocity corresponding to the alternating region.

Based on the same inventive concept, the embodiments of the present application further provide a filter, where the filter at least includes a plurality of elastic wave devices as described above.

In summary, the filter provided by the implementation of the present application includes a plurality of elastic wave devices, where the elastic wave devices are provided with mass layers in alternating regions of the interdigital transducer to reduce the propagation speed of the acoustic wave in the alternating regions, so that the required electrode finger period is reduced compared with the existing electrode finger period when the same resonant frequency is achieved, thereby reducing the size of the interdigital transducer in terms of technology and realizing the miniaturization design of the elastic wave devices.

Based on the same inventive concept, the embodiment of the application also provides an electronic device, which comprises a substrate and the filter, wherein the filter is mounted on the substrate and is electrically connected with the substrate.

In summary, the electronic device provided in the embodiment of the present application includes a substrate and a filter, where the filter includes a plurality of elastic wave devices, and the elastic wave devices are configured with a mass layer in an alternating region of the interdigital transducer, so as to reduce a speed of propagation of an acoustic wave in the alternating region, so that a required electrode finger period is reduced compared with an existing electrode finger period when implementing the same resonant frequency, thereby reducing a size of the interdigital transducer in a process, and implementing a miniaturized design of the elastic wave device.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic top view of an elastic wave device according to an embodiment of the present disclosure;

FIG. 2 is a schematic cross-sectional view of the elastic wave device shown in FIG. 1 along the direction II-II;

FIG. 3 is a schematic view of the interdigital transducer of the elastic wave device depicted in FIG. 1;

FIG. 4 is a layer structure corresponding to the middle region of the elastic wave device shown in FIG. 1;

FIG. 5 is a layer structure corresponding to an edge region of the elastic wave device shown in FIG. 1;

FIG. 6 is a layer structure corresponding to the gap region of the elastic wave device shown in FIG. 1;

FIG. 7 is a layer structure corresponding to a side region of the elastic wave device shown in FIG. 1;

FIG. 8 is a schematic diagram showing the admittance curves of an elastic wave device according to the present disclosure in comparison with the admittance curves of an elastic wave device according to the prior art;

FIG. 9 is a diagram showing the quality factor of an elastic wave device according to an embodiment of the present disclosure in comparison with the quality factor of an elastic wave device according to the prior art;

FIG. 10 is a schematic diagram of the energy distribution of a prior art elastic wave device;

FIG. 11 is a schematic view of the energy distribution of the elastic wave device disclosed in the present application;

fig. 12 is a schematic structural diagram of a filter according to an embodiment of the present application.

Reference numerals illustrate:

10-a piezoelectric layer; a 30-interdigital transducer; 31-bus bars; 33-electrode fingers; 50-a temperature compensation layer; 60-mass layer;

70-mass loading structure; 80-a high acoustic velocity layer; 100-elastic wave device; a-alternating regions; a C-middle region; q-edge region; a K-gap region; an N-side region; 200-a filter; an IN input; an OUT-output terminal; bl-series branch; b2-parallel branch; GND-ground.

Detailed Description

In order to facilitate an understanding of the present application, a more complete description of the present application will now be provided with reference to the relevant figures. Preferred embodiments of the present application are shown in the accompanying drawings. This application may, however, be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

The following description of the embodiments refers to the accompanying drawings, which illustrate specific embodiments that can be used to practice the present application. The numbering of the components itself, e.g. "first", "second", etc., is used herein merely to distinguish between the described objects and does not have any sequential or technical meaning. The terms "coupled" and "connected," as used herein, are intended to encompass both direct and indirect coupling (coupling), unless otherwise indicated. Directional terms referred to in this application, such as "upper", "lower", "front", "rear", "left", "right", "inner", "outer", "side", etc., are merely directions referring to the attached drawings, and thus, directional terms are used for better, more clear description and understanding of the present application, rather than indicating or implying that the apparatus or element being referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present application.

In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; may be a mechanical connection; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art in a specific context. It should be noted that the terms "first," "second," and the like in the description and claims of the present application and in the drawings are used for distinguishing between different objects and not for describing a particular sequential order. Furthermore, the terms "comprises," "comprising," "includes," "including," "may be" or "including" as used in this application mean the presence of the corresponding function, operation, element, etc. disclosed, but not limited to other one or more additional functions, operations, elements, etc. Furthermore, the terms "comprises" or "comprising" mean that there is a corresponding feature, number, step, operation, element, component, or combination thereof disclosed in the specification, and that there is no intention to exclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations thereof. It will also be understood that the meaning of "at least one" as described herein is one and more, such as one, two or three, etc., and the meaning of "a plurality" is at least two, such as two or three, etc., unless specifically defined otherwise.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

Referring to fig. 1 and 2, fig. 1 is a schematic top view of an elastic wave device according to an embodiment of the present application, and fig. 2 is a schematic cross-sectional view of the elastic wave device shown in fig. 1 along a direction II-II, where the elastic wave device 100 provided in the embodiment of the present application includes a piezoelectric layer 10, an interdigital transducer 30 located on the piezoelectric layer 10, and reflective structures disposed on opposite sides of the interdigital transducer 30. The interdigital transducer 30, in cooperation with the piezoelectric layer 10, can convert an electrical signal into an acoustic wave or an acoustic wave into an electrical signal, and the reflective structure is used to prevent leakage of the acoustic wave.

In the embodiment of the present application, the elastic wave device may be a temperature compensated surface acoustic wave resonator (TC-SAW), a surface acoustic wave resonator having a POI substrate structure, or an elastic wave device having an interdigital transducer such as a transverse excitation thin film bulk acoustic wave resonator, which is not limited herein.

In this embodiment, please refer to fig. 2 and 3 together, fig. 3 is a schematic structural diagram of an interdigital transducer of the elastic wave device shown in fig. 1, the interdigital transducer 30 includes two bus bars 31 and a plurality of electrode fingers 33, the two bus bars 31 are oppositely disposed, one end of each electrode finger 33 is connected to one bus bar 31, the other end of each electrode finger 33 extends to the other bus bar 31, and a plurality of electrode fingers 33 connected to the two bus bars 31 are sequentially disposed at intervals in the acoustic wave propagation direction to form an alternating region a. Wherein the propagation direction of the sound wave is perpendicular to the arrangement direction of the two bus bars 31.

In this embodiment, referring to fig. 1 and 2, the elastic wave device 100 further includes a temperature compensation layer 50 and a mass layer 60, where the temperature compensation layer 50 is disposed on a side of the piezoelectric layer 10 where the interdigital transducer 30 is disposed, and covers at least the alternating region a of the interdigital transducer 30. The mass layer 60 is disposed on a side of the temperature compensation layer 50 facing away from the interdigital transducer 30 and is located in the alternating region a.

It will be appreciated that the mass layer 60 acts to reduce the speed of sound wave propagation in the alternating region a such that sound waves have a lower speed of sound in that region than when the mass layer 60 is uncovered. As can be seen from the sound velocity (V) =wavelength (λ) ×frequency (f), decreasing the sound velocity V can decrease the wavelength λ, where the wavelength λ may also refer to the period of the electrode finger, specifically: on the same bus bar, the distance between the center lines of two adjacent electrode fingers.

Typically, the resonant frequency of the elastic wave device is structurally related to the period of the electrode fingers. Therefore, when the elastic wave device realizes the same resonance frequency f, the propagation speed of the acoustic wave can be reduced by the design, and the interdigital transducer can be made small in size during the design, thereby realizing the miniaturization design of the elastic wave device.

In the exemplary embodiment, two of the bus bars 31 are disposed opposite and in parallel, and the extending direction of the electrode fingers 33 is perpendicular to the propagation direction of the acoustic wave.

In an exemplary embodiment, the piezoelectric layer 10 may be any cut type of lithium tantalate (LiTaO) ₃ ) Lithium niobate (LiNbO) ₃ ) Single crystal material or other piezoelectric material.

In an exemplary embodiment, the material of the interdigital transducer 30 includes any one or more of aluminum (Al), copper (Cu), silver (Ag), platinum (Pt), chromium (Cr), and the like. The interdigital transducer 30 includes a one-layer film structure or a multi-layer film structure which are sequentially laminated.

In an exemplary embodiment, the temperature compensation layer 50 may have a positive temperature coefficient to compensate for the negative temperature coefficient of the piezoelectric layer 10. The material of the temperature compensation layer 50 includes, but is not limited to, silicon dioxide, fluorine-containing silicon dioxide, silicon nitride-based silicon-containing dielectric films, and the like.

In an exemplary embodiment, the temperature compensation layer 50 covers the interdigital transducer 30 and covers the side of the piezoelectric layer 10 on which the interdigital transducer 30 is disposed.

In an exemplary embodiment, other functional layers may be further disposed on a side of the mass Layer 60 facing or facing away from the temperature compensation Layer 50, for example, a passivation Layer may be disposed on a side of the mass Layer 60 facing away from the temperature compensation Layer 50, and the passivation Layer may also play a role in frequency modulation, and a seed Layer and a Buffer Layer may be disposed on a side of the mass Layer 60 facing toward the temperature compensation Layer 50.

In summary, in the elastic wave device 100 provided in the embodiment of the present application, the mass layer 60 is disposed in the alternating area a of the interdigital transducer 30 to reduce the propagation speed of the sound wave in the alternating area a, so that the period of the electrode finger 33 required for realizing the same resonant frequency is reduced compared with the conventional one, thereby reducing the size of the interdigital transducer 30 in terms of process and realizing the miniaturization design of the elastic wave device 100.

In the embodiment of the present application, please refer to fig. 1, fig. 4 and fig. 5 together, fig. 4 is a layer structure corresponding to a middle region of the elastic wave device shown in fig. 1, and fig. 5 is a layer structure corresponding to an edge region of the elastic wave device shown in fig. 1. The alternating region a includes a middle region C and edge regions Q located at two sides of the middle region C, the elastic wave device 100 further includes a mass load structure 70, in a top view, the mass load structure 70 is located at the edge region Q, the mass load structure 70 is configured to reduce a sound velocity corresponding to the edge region Q, and the sound velocity corresponding to the middle region C is greater than the sound velocity corresponding to the edge region Q. The direction from the mass layer 60 to the piezoelectric layer 10 is a top view.

In this embodiment, the mass loading structure 70 includes a plurality of mass loading blocks, in the arrangement direction of the plurality of electrode fingers 33, the plurality of mass loading blocks are sequentially spaced, and in the top view direction, at least part of the electrode fingers 33 overlap at least one mass loading block. In an exemplary embodiment, at least a portion of the electrode fingers 33 overlap at least one of the mass loading blocks. Specifically, each of the electrode fingers 33 may overlap one mass load block or a plurality of the mass load blocks, or a part of the electrode fingers 33 may overlap one mass load block or a plurality of the mass load blocks, which is not particularly limited in this application.

In an exemplary embodiment, overlapping refers to: the front projection of the mass-carrying mass onto the piezoelectric layer 10 coincides or partially coincides with the front projection of the electrode finger 33 located in the edge region Q onto the piezoelectric layer 10.

In an exemplary embodiment, the size of the orthographic projection of the mass-carrying mass on the piezoelectric layer 10 may be greater than, less than or equal to the size of the orthographic projection of the electrode finger 33 located in the edge region Q on the piezoelectric layer 10.

In an exemplary embodiment, the mass-loading structure 70 overlaps with the plurality of electrode fingers 33 and the gaps between the adjacent two electrode fingers 33 in the top view.

In an exemplary embodiment, the mass-loaded structure 70 may be one piece. The mass loading structure 70 may be one or two. Accordingly, one of the mass-loading structures 70 may be located at the one of the edge regions Q, and two of the mass-loading structures 70 may be located at the two of the edge regions Q, respectively.

In an embodiment of the present application, the mass loading structure 70 may be one mass loading bar, which covers the entire edge region Q, i.e. the mass loading bar covers the electrode fingers 33 of the edge region Q and the gap between two adjacent electrode fingers 33.

In another embodiment of the present application, the mass-loading structure 70 may be a plurality of mass-loading bars that intermittently cover portions of the electrode fingers 33 and/or gaps between adjacent electrode fingers 33.

In other embodiments of the present application, the mass loading structure may be a plurality of mass loading blocks, and the plurality of mass loading blocks are disposed at intervals in the edge region Q so as to cover a portion of the electrode fingers 33 located in the edge region Q, a portion of gaps between the electrode fingers 33 located in the edge region Q, or gaps between the electrode fingers 33, which are not particularly limited in this application. It will be appreciated that the mass-loading structure 70 may be piston, hammer or another form of structure, with the mass-loading structure 70 being disposed at the edge region Q to reduce the speed of sound corresponding to the edge region Q. The mass loading structure 70 is configured such that the sound velocity of the sound wave propagating in the edge region Q is smaller than that of the sound wave propagating in the middle region C, so as to form a sound velocity difference, avoid the sound wave leakage in the middle region C, and further inhibit the transverse mode of the elastic wave device 100.

In an exemplary embodiment, two of the mass-loading structures 70 are located in two of the edge regions Q, respectively, and the positions of the mass-loading structures 70 correspond to the positions of the plurality of the electrode fingers 33; alternatively, the mass-loading structures 70 are respectively located in the two edge regions Q, and the positions of the mass-loading structures 70 in one edge region Q are respectively in one-to-one correspondence with the positions of the electrode fingers 33. It will be appreciated that the process of forming two of the mass-loaded structures 70 is simpler, with two of the mass-loaded structures 70 covering two of the edge regions Q.

In an exemplary embodiment, the mass loading structures 70 of two of the edge regions Q may be the same or different. Specifically, the mass loading structures 70 of the two edge regions Q may be one mass loading bar, a plurality of mass loading bars, or a plurality of mass loading blocks; the mass loading structure 70 of one of the edge regions Q may be one of the mass loading bars, and the mass loading structure 70 of the other of the edge regions Q may be a plurality of the mass loading bars or a plurality of mass loading blocks; the mass loading structure 70 of one of the edge regions Q may be a plurality of the mass loading bars, and the mass loading structure 70 of the other of the edge regions Q may be one of the mass loading bars or a plurality of mass loading blocks; the mass loading structure 70 of one of the edge regions Q may be a plurality of mass loading blocks, and the mass loading structure 70 of the other of the edge regions Q may be a plurality of mass loading bars or one of the mass loading bars.

In an exemplary embodiment, the alternating region a includes two edge regions Q, and the two edge regions Q are disposed at opposite sides of the middle region C, respectively. The arrangement direction of the middle area C and the edge area Q is perpendicular to the propagation direction of the sound wave.

In an exemplary embodiment, the free ends of the partial electrode fingers 33 (the ends of the electrode fingers 33 facing away from the connected bus bars 31) may be located at or beyond the edge region Q. Wherein, the location of the edge region Q can be understood as: the length of the electrode finger 33 in the edge region Q may be equal to or less than the width of the edge region Q. The width of the edge area Q refers to: the edge region Q is a distance from one side to the opposite side in the extending direction of the electrode finger 33.

In the present embodiment, the mass loading structure 70 is disposed on a side of the mass layer 60 facing the temperature compensation layer 50; alternatively, the mass loading structure 70 is disposed on a side of the mass layer 60 opposite to the temperature compensation layer 50, which is not particularly limited in this application.

In an exemplary embodiment, the mass-loading structure 70 may or may not be in contact with the electrode fingers 33, which is not particularly limited in this application. The mass loading structure 70 may be located on a side of the electrode finger 33 facing the piezoelectric layer 10 or a side facing away from the piezoelectric layer 10, which is not particularly limited in this application.

In an exemplary embodiment, the material of the mass layer 60 includes a metal, an alloy, or a dielectric material, and the material of the mass loading structure 70 includes a metal, an alloy, or a dielectric material, which is not particularly limited in this application. The material of the mass loading structure 70 may be any one of aluminum (Al), copper (Cu), tungsten (W), molybdenum (Mo), gold (Au), silver (Ag), platinum (Pt) and chromium (Cr), or may be an alloy containing metals such as aluminum, copper, tungsten, molybdenum, gold, silver, platinum and chromium as main components. The dielectric material may be a low sound speed material such as tantalum pentoxide.

In an exemplary embodiment, the mass layer 60 has a density greater than or equal to a metal of Al and alloys thereof, or the mass layer 60 has a density greater than 4.5g/cm ³ Metal or density greater than 4.5g/cm ³ Is a dielectric material of (a). A metal having a density of the mass-loaded structure 70 greater than or equal to Al, or an alloy thereof, or a density of the mass-loaded structure 70 greater than 4.5g/cm ³ Metal or density greater than 4.5g/cm ³ Is a dielectric material of (a).

Preferably, the mass layer 60 has a density of greater than 4.5g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the And/or the mass loading structure 70 has a density greater than 4.5g/cm ³ The mass layer 60 and the mass The material of the mass-loading structure 70 may be a metal, an alloy or a dielectric material, and the mass layer 60 and the mass-loading structure 70 may be the same or different.

Preferably, the mass layer 60 and the mass loading structure 70 are both made of heavy metal. In an exemplary embodiment, the material of the mass layer 60 and the material of the mass loading structure 70 may be the same or different, which is not particularly limited in this application.

In the present embodiment, the mass layer 60 includes a metal film or a plurality of metal films stacked in order; and/or the mass-loaded structure 70 comprises a layer of metal film or a plurality of layers of metal films which are sequentially stacked.

In this embodiment, referring to fig. 1 and fig. 6 together, fig. 6 is a layer structure corresponding to a gap region of the elastic wave device shown in fig. 1, and the interdigital transducer 30 further includes a gap region K, where the gap region K is adjacent to a side of the edge region Q opposite to the middle region C. The elastic wave device 100 further includes a high sound velocity layer 80, where the high sound velocity layer 80 is at least disposed in the gap region K, and the high sound velocity layer 80 is configured to increase the sound velocity of the sound wave corresponding to the region where the high sound velocity layer 80 is located.

It will be appreciated that the speed at which sound waves propagate in the gap region K is greater than the speed at which sound waves propagate in the edge region Q, such that a difference in sound speed is formed between the gap region K and the edge region Q to confine the sound waves to the intermediate region C, preventing leakage of sound wave energy.

In an embodiment of the present application, the high acoustic velocity layer 80 may be in the same plane as the mass layer 60. The high acoustic velocity layer 80 is located on the side of the temperature compensation layer 50 facing away from the interdigital transducer 30 and is disposed adjacent to the mass layer 60.

In another embodiment of the present application, the high acoustic velocity layer 80 may be coplanar with the temperature compensation layer 50. The high acoustic velocity layer 80 is located on the side of the interdigital transducer 30 facing away from the piezoelectric layer 10 and is disposed adjacent to the temperature compensation layer 50.

In an exemplary embodiment, the interdigital transducer 30 further comprises two gap regions K, which are respectively located on the sides of the two edge regions Q facing away from the middle region C.

In this embodiment, referring to fig. 1 and fig. 7 together, fig. 7 is a layer structure corresponding to a side region of the elastic wave device shown in fig. 1, the elastic wave device 100 further includes a side region N, the side region N is adjacent to a side of the gap region K opposite to the edge region Q, and at least a portion of the bus bar 31 is located in the side region N, where a speed of sound wave propagating in the side region N is greater than a speed of sound wave propagating in the middle region C.

It is understood that the side area N includes at least two portions of the bus bars 31 facing each other (the inner area of the bus bars near the electrode fingers), and may include the entire bus bars 31, which is not particularly limited in this application.

It will be appreciated that the acoustic Wave generated in the alternating region a enters the gap region K in the form of an Evanescent Wave, the energy intensity of which decays exponentially with the depth of the acoustic Wave into the gap region K. When the distance between the side of the gap region K facing the alternating region a and the side facing away from the alternating region a is sufficiently wide, the sound wave can be emitted completely, so that the sound wave is confined in the alternating region a, and the energy leakage of the sound wave is avoided, thereby affecting the performance of the elastic wave device 100. When the width of the gap region K is small, the sound wave entering the gap region K passes through the gap region K and enters the side region N, the sound wave passing through the gap region K enters the side region N in the form of evanescent wave, the energy of the sound wave also rapidly decays to zero, the width of the gap region K is reduced, a certain width of the side region N is ensured, and the energy leakage of the sound wave of the alternating region a can be prevented. Therefore, in compressing the width of the gap region K to a process limit and ensuring that the free ends of the electrode fingers 33 are not in contact with the bus bar 31, the gap region K is greatly weakened or even negligible due to the existence of the acoustic tunneling effect, and the function of the gap region K is only to achieve insulation of the free ends of the electrode fingers 33 from the bus bar 31, which is advantageous for achieving miniaturization of the elastic wave device 100 due to the great compression of the width of the gap region K.

In the embodiment of the present application, the length of the gap region K in the extending direction of the electrode finger 33 is less than or equal to 0.5λ, for example, 0.5λ, 0.4λ, 0.3λ, 0.35λ,0.25λ,0.2λ, 0.1λ, which is not particularly limited in the present application. Where λ is the period of the electrode finger 33. At least one of the gap regions K is not particularly limited in this application, and the length of the gap region K is 0.5λ or less.

In the embodiment of the present application, the length of the gap region K in the extending direction of the electrode finger 33 is less than or equal to 0.25λ, for example, 0.25λ, 0.23λ,0.2λ, 0.18λ, 0.15λ, 0.1λ, 0.08λ, 0.07 λ, 0.02λ, which is not particularly limited in the present application. Where λ is the period of the electrode finger 33. At least one of the gap regions K is not particularly limited in this application, and the length of the gap region K is 0.25λ or less.

It will be appreciated that the speed of sound wave propagation in the side region N is greater than the speed of sound wave propagation in the middle region C, so that the region of greater sound velocity of sound wave has a sufficient width, and further the length of the gap region K may be made smaller than or equal to 0.5 λ and the length of the gap region K is smaller than or equal to 0.25 λ.

In the embodiment of the present application, the high sound velocity layer 80 is disposed in the gap region K and the side region N, so as to further increase the sound velocity corresponding to the gap region K and the side region N.

In the present embodiment, the material of the high acoustic velocity layer 80 includes any one or more of silicon nitride, aluminum oxide, and silicon carbide.

In this embodiment, in the extending direction of the electrode finger 33, the length of the gap region K is less than or equal to λ, where λ is the period of the electrode finger 33.

In an exemplary embodiment, referring to fig. 8, fig. 8 is a schematic diagram illustrating the comparison of an admittance curve of an elastic wave device disclosed in the present application with an admittance curve of an elastic wave device of the prior art, where the abscissa of fig. 8 is frequency, in Hz, and the ordinate is admittance curve, in dB. As can be seen from fig. 8, changing the width of the gap region K of the elastic wave device 100 according to the prior art does not affect the suppression of the transverse mode, while the width of the gap region K of the elastic wave device 100 according to the present disclosure is 0.25λ.

In an exemplary embodiment, referring to fig. 9, fig. 9 is a schematic diagram comparing the quality factor of the elastic wave device disclosed in the embodiment of the present application with the quality factor of the elastic wave device of the prior art, and the abscissa of fig. 9 is frequency, hz, and the ordinate is quality factor. As can be seen from fig. 9, in the vicinity of the resonance point, the quality factor of the elastic wave device 100 of the present application is significantly higher than that of the elastic wave device of the prior art, and in other frequency ranges, the quality factor of the elastic wave device 100 of the present application is not significantly different from that of the elastic wave device of the prior art.

In an exemplary embodiment, please refer to fig. 10 and 11 together, fig. 10 is a schematic energy distribution diagram of an elastic wave device in the prior art, and fig. 11 is a schematic energy distribution diagram of an elastic wave device disclosed in the present application, wherein an inner portion of a white circle in fig. 10 and 11 is an area where energy is located. It can be seen from fig. 11 that after the sound wave enters the gap region K, the energy is rapidly attenuated to zero, and from fig. 10, after the sound wave passes through the gap region K and enters the side region N, the energy is rapidly attenuated to zero, and the energy can pass through the gap region K due to the acoustic tunneling effect. Therefore, after the gap region K is very narrow (after the size of the elastic wave device 100 is reduced), the elastic wave device 100 provided in the present application can also quickly attenuate the energy of the sound wave through the side region N, so as to further realize the full emission of the sound wave. Increasing the sound velocity corresponding to at least a portion of the bus bar 31 may reduce the length of the gap region K.

Based on the same inventive concept, the embodiment of the present application further provides an elastic wave device 100, where the elastic wave device includes a piezoelectric layer 10, an interdigital transducer 30 located on the piezoelectric layer 10, and reflective structures disposed on opposite sides of the interdigital transducer 30, the interdigital transducer 30 includes two bus bars 31 and a plurality of electrode fingers 33 disposed opposite to each other, one end of each electrode finger 33 is connected to one bus bar 31, the other end of each electrode finger 33 extends toward the other bus bar 31, and the plurality of electrode fingers 33 on the two bus bars 31 are sequentially disposed at intervals in the acoustic wave propagation direction to form an alternating region a, where the alternating region a includes a middle region C and edge regions Q located on both sides of the middle region C. The elastic wave device 100 further includes a temperature compensation layer 50 and a mass layer 60, the temperature compensation layer 50 is disposed on a side of the piezoelectric layer 10 where the interdigital transducer is disposed and covers at least the alternating region a of the interdigital transducer, the mass layer 60 is disposed on a side of the temperature compensation layer 50 opposite to the interdigital transducer 30 and is located in the alternating region a, and the mass layer 60 is configured to reduce the sound velocity corresponding to the alternating region a. The other structures of the elastic wave device are the same as those of the elastic wave device of the previous embodiment, and will not be described here again.

Based on the same inventive concept, please refer to fig. 12, fig. 12 is a schematic structural diagram of a filter disclosed in an embodiment of the present application. The embodiment of the present application further provides a filter, where the filter 200 includes at least a plurality of the elastic wave devices 100 described above.

IN the embodiment of the present application, the filter may further include at least an input terminal IN, an output terminal OUT, a series branch Bl, and at least one parallel branch B2. Wherein the serial branch Bl is connected between the input end IN and the output end OUT, one end of the parallel branch B2 is connected with the serial branch Bl, and the other end is connected with the grounding end GND; at least two elastic wave devices 100 connected in series are arranged in the series branch line Bl, and the elastic wave devices 100 connected in parallel are arranged in each parallel branch line B2. Since the embodiment shown in fig. 1 to 11 has been described in detail, the description of the elastic wave device 100 is omitted here.

In summary, the filter 200 provided in the embodiment of the present application includes a plurality of elastic wave devices 100, and the mass layer 60 is disposed in the alternating area a of the interdigital transducer 30 to reduce the propagation speed of the sound wave in the alternating area a, so that the period of the electrode finger 33 required for realizing the same resonant frequency is reduced compared with the conventional one, thereby reducing the size of the interdigital transducer 30 in terms of process and realizing the miniaturization design of the elastic wave device 100.

Based on the same inventive concept, the embodiment of the present application further provides an electronic device, which includes a substrate and the above-mentioned filter 200, where the filter 200 is flip-chip mounted on the substrate and is electrically connected to the substrate.

In an exemplary embodiment, the substrate may be a printed circuit board (Printed Circuit Board, PCB).

In an exemplary embodiment, the electronic device includes, but is not limited to: any electronic device or component with a filter, such as an LED panel, a tablet, a notebook, a navigator, a mobile phone, and an electronic watch, is not particularly limited in this application.

It will be appreciated that the electronic device may also include electronic devices such as personal digital assistants (Personal Digital Assistant, PDAs) and/or music player functions, such as cell phones, tablet computers, wearable electronic devices with wireless communication functions (e.g., smart watches), etc. The electronic device may also be other electronic means, such as a Laptop computer (Laptop) or the like having a touch sensitive surface, e.g. a touch panel. In some embodiments, the electronic device may have a communication function, that is, may establish communication with a network through a 2G (second generation mobile phone communication specification), a 3G (third generation mobile phone communication specification), a 4G (fourth generation mobile phone communication specification), a 5G (fifth generation mobile phone communication specification), a 6G (sixth generation mobile phone communication specification), or a W-LAN (wireless local area network) or a communication manner that may occur in the future. For the sake of brevity, this embodiment of the present application is not further limited. Since the embodiment shown in fig. 1 to 12 has been described in detail for the elastic wave device 100 and the filter 200, the description thereof is omitted here.

In summary, the electronic device provided in the embodiment of the present application includes the substrate and the filter 200, where the filter 200 includes the plurality of elastic wave devices 100, and the elastic wave devices 100 set the mass layer 60 in the alternating area a of the interdigital transducer 30 to reduce the propagation speed of the sound wave in the alternating area a, so that the period of the electrode finger 33 required for implementing the same resonant frequency is reduced compared with the conventional one, so that the size of the interdigital transducer 30 can be reduced in terms of technology, and the miniaturized design of the elastic wave devices 100 is realized.

In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

It is to be understood that the application of the present application is not limited to the examples described above, but that modifications and variations can be made by a person skilled in the art from the above description, all of which modifications and variations are intended to fall within the scope of the claims appended hereto. Those skilled in the art will recognize that the methods of accomplishing all or part of the above embodiments and equivalents thereof may be employed and still fall within the scope of the present application.

Claims

1. The elastic wave device comprises a piezoelectric layer, an interdigital transducer positioned on the piezoelectric layer and reflecting structures arranged on two opposite sides of the interdigital transducer, and is characterized in that the interdigital transducer comprises two bus bars and a plurality of electrode fingers which are oppositely arranged, one end of each electrode finger is connected with one bus bar, the other end of each electrode finger extends to the other bus bar, and the plurality of electrode fingers connected with the two bus bars are sequentially arranged at intervals in the sound wave propagation direction to form an alternating region;

the elastic wave device further comprises a temperature compensation layer and a quality layer, wherein the temperature compensation layer is arranged on one side of the piezoelectric layer, provided with the interdigital transducer, and at least covers the alternating region of the interdigital transducer, and the quality layer is arranged on one side of the temperature compensation layer, which is opposite to the interdigital transducer, and is positioned in the alternating region.

2. The elastic wave device of claim 1, wherein the alternating regions comprise a middle region and edge regions on either side of the middle region;

the elastic wave device further comprises a mass loading structure, wherein the mass loading structure is positioned at the edge area in a top view direction.

3. The elastic wave device of claim 2, wherein the mass-loaded structure is disposed on a side of the mass layer facing the temperature compensation layer; or alternatively, the first and second heat exchangers may be,

the mass loading structure is arranged on one side of the mass layer, which is opposite to the temperature compensation layer.

4. The elastic wave device according to claim 2, wherein the mass loading structure comprises a plurality of mass loading blocks, the plurality of mass loading blocks are sequentially arranged at intervals in an arrangement direction of the plurality of electrode fingers, and at least a part of the electrode fingers overlap with at least one of the mass loading blocks in a top view direction.

5. The elastic wave device according to claim 2, wherein the mass-loaded structure overlaps with the plurality of the electrode fingers 33 and the gaps between the adjacent two of the electrode fingers 33 in a plan view.

6. The elastic wave device of claim 2, wherein the mass layer has a density greater than 4.5g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the And/or the number of the groups of groups,

the density of the mass-loaded structure is greater than 4.5g/cm ³ 。

7. The elastic wave device of claim 2, wherein the material of the mass layer comprises at least one of aluminum, copper, tungsten, molybdenum, gold, silver, platinum, and chromium; and/or the number of the groups of groups,

the material of the mass-loaded structure comprises at least one of aluminum, copper, tungsten, molybdenum, gold, silver, platinum and chromium.

8. The elastic wave device according to claim 2, wherein the mass layer comprises a metal film or a plurality of metal films laminated in this order; and/or the number of the groups of groups,

the mass loading structure comprises a layer of metal film or a plurality of layers of metal films which are sequentially laminated.

9. The acoustic wave device of claim 2, wherein the interdigital transducer further comprises a gap region adjacent to a side of the edge region opposite the intermediate region;

the elastic wave device further comprises a high sound velocity layer, wherein the high sound velocity layer is at least arranged in the gap area, and the high sound velocity layer is configured to increase sound velocity corresponding to the area where the high sound velocity layer is located.

10. The elastic wave device of claim 9, further comprising a side region adjacent to a side of the gap region opposite the edge region, and at least a portion of the bus bar is located in the side region, wherein the sound velocity corresponding to the side region is greater than the sound velocity corresponding to the middle region.

11. The acoustic wave device of claim 10, wherein the high acoustic velocity layer is disposed in the gap region and the side region.

12. The elastic wave device of claim 9, wherein the material of the high acoustic velocity layer comprises any one or more of silicon nitride, aluminum oxide, and silicon carbide.

13. The elastic wave device of claim 9, wherein a length of the gap region in the electrode finger extending direction is less than or equal to λ, where λ is a period of the electrode finger.

14. The elastic wave device of claim 10, wherein a length of the gap region in the electrode finger extension direction is less than or equal to 0.5 λ, where λ is a period of the electrode finger.

15. The elastic wave device of claim 10, wherein a length of the gap region in the electrode finger extension direction is less than or equal to 0.25 λ, where λ is a period of the electrode finger.

16. The elastic wave device comprises a piezoelectric layer, an interdigital transducer arranged on the piezoelectric layer and reflecting structures arranged on two opposite sides of the interdigital transducer, and is characterized in that the interdigital transducer comprises two bus bars and a plurality of electrode fingers which are arranged oppositely, one end of each electrode finger is connected with one bus bar and extends towards the other bus bar, the electrode fingers connected with the two bus bars are sequentially arranged at intervals in the sound wave propagation direction to form an alternating region, and the alternating region comprises a middle region and edge regions positioned on two sides of the middle region;

The elastic wave device further comprises a temperature compensation layer and a mass layer, wherein the temperature compensation layer is arranged on one side of the piezoelectric layer, provided with the interdigital transducer, and at least covers the alternating region of the interdigital transducer, the mass layer is arranged on one side of the temperature compensation layer, which is opposite to the interdigital transducer, and is positioned in the alternating region, and the mass layer is configured to reduce sound velocity corresponding to the alternating region.

17. A filter comprising at least a plurality of elastic wave devices according to any one of claims 1-16.

18. An electronic device comprising a substrate and the filter of claim 17 mounted on the substrate and electrically connected to the substrate.