Elastic wave device and multiplexer

Abstract

The invention relates to the technical field of communication, and provides an elastic wave device and a multiplexer, and the elastic wave device comprises a piezoelectric substrate; the IDT electrode layer is arranged on the piezoelectric substrate and comprises an IDT electrode, a first reflector and a second reflector, and the first reflector and the second reflector are configured to clamp the IDT electrode on the main surface of the piezoelectric substrate in the first direction; a dielectric layer provided between the piezoelectric substrate and the IDT electrode; wherein the projection of the dielectric layer on the main surface perpendicular to the piezoelectric substrate is configured to cover the partial projection of the IDT electrode on the main surface perpendicular to the piezoelectric substrate; wherein the dielectric layer comprises a linear change region and a non-linear change region which are distributed along a second direction, and the linear change region and the non-linear change region are configured in such a manner that the areas of projection regions on the main surface perpendicular to the piezoelectric substrate are linearly changed and non-linearly changed along the second direction respectively. According to the invention, in-band stray can be suppressed on the multi-layer composite piezoelectric substrate, and the passband performance of the filter is improved.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to an elastic wave device and a multiplexer. Background Art

[0002] With the advent of the mobile communication era, there are more and more communication frequency bands and higher integration. The clarity requirements of wirelessly transmitted pictures and videos are getting higher and higher, the size of equipment is getting smaller and smaller, and the number of integrated devices is increasing. Mobile phones and base stations mostly use filters, duplexers and multiplexers composed of elastic wave devices.

[0003] With the advent of 5G, higher requirements are placed on the performance of filters, duplexers and multiplexers. Filters, duplexers and multiplexers composed of elastic wave devices are required to have high power capacity, low loss and large bandwidth. Traditional elastic wave filters use a single piezoelectric material as a substrate, and it is inevitable that energy will leak into the piezoelectric material, resulting in a low Q value. Multi-layer composite substrates can effectively prevent energy from leaking into the piezoelectric material, increase the Q value and bandwidth, and improve power capacity and temperature performance. Although the composite substrate improves the performance of the elastic wave device, it will form spurious signals within the band, affecting the passband performance.

[0004] Therefore, how to suppress in-band spurious signals and improve the passband performance of filters on multi-layer composite piezoelectric substrates is a technical problem that needs to be solved urgently. Summary of the invention

[0005] The present invention provides an elastic wave device and a multiplexer, aiming to solve at least one of the above-mentioned prior art problems.

[0006] According to a first aspect of the present invention, there is provided an elastic wave device, comprising: Piezoelectric substrate; An IDT electrode layer is disposed on the piezoelectric substrate; The IDT electrode layer includes an IDT electrode, a first reflector and a second reflector, and the first reflector and the second reflector are configured to sandwich the IDT electrode on the main surface of the piezoelectric substrate along a first direction; A dielectric layer is disposed between the piezoelectric substrate and the IDT electrode; wherein the projection of the dielectric layer on the main surface perpendicular to the piezoelectric substrate is configured to cover a portion of the projection of the IDT electrode on the main surface perpendicular to the piezoelectric substrate; In which, the dielectric layer includes a linear change zone and a nonlinear change zone distributed along the second direction, the linear change zone is configured so that the projected area on the main surface perpendicular to the piezoelectric substrate changes linearly along the second direction, and the nonlinear change zone is configured so that the projected area on the main surface perpendicular to the piezoelectric substrate changes nonlinearly along the second direction.

[0007] Optionally, the piezoelectric substrate comprises: A multi-layer substrate configured to have at least two substrate layers arranged in a stacked manner; A piezoelectric substrate is disposed on the multi-layer substrate; wherein a side of the piezoelectric substrate away from the multi-layer substrate is configured as a main surface of the piezoelectric substrate.

[0008] Optionally, the IDT electrode comprises: a first IDT electrode strip and a second IDT electrode strip; The first IDT electrode strip includes a first bus bar and a plurality of first fingers disposed perpendicularly to the first bus bar on the main surface of the piezoelectric substrate, and the second IDT electrode strip includes a second bus bar and a plurality of second fingers disposed perpendicularly to the second bus bar on the main surface of the piezoelectric substrate; The first bus bar and the second bus bar are arranged in parallel along the second direction on the main surface of the piezoelectric substrate, and the plurality of first fingers and the plurality of second fingers are arranged in parallel and cross each other along the first direction on the main surface of the piezoelectric substrate.

[0009] Optionally, the first reflector and the second reflector are respectively arranged on the first side and the second side of the IDT electrode along the first direction on the main surface of the piezoelectric substrate, and are configured as reflection gratings with the elastic wave reflection direction pointing to the IDT electrode.

[0010] Optionally, the dielectric layer comprises: a first dielectric layer and a second dielectric layer; Wherein, the first dielectric layer and the second dielectric layer include a linear change region and a nonlinear change region distributed along the second direction; The linear change regions of the first dielectric layer and the second dielectric layer are arranged in parallel along a second direction on the main surface of the piezoelectric substrate, and the nonlinear change regions of the first dielectric layer and the second dielectric layer are respectively arranged on a side of the first dielectric layer close to the second dielectric layer and a side of the second dielectric layer close to the first dielectric layer.

[0011] Optionally, two first projections of the linear change regions of the first dielectric layer and the second dielectric layer on a main surface perpendicular to the piezoelectric substrate are configured to respectively cover two second projections of the first bus bar and the second bus bar on a main surface perpendicular to the piezoelectric substrate.

[0012] Optionally, two third projections of the nonlinear change zones of the first dielectric layer and the second dielectric layer on the main surface perpendicular to the piezoelectric substrate are configured to cover partial areas of several fourth projections of the several first fingers and several second fingers arranged in parallel and crossing each other on the main surface perpendicular to the piezoelectric substrate.

[0013] Optionally, the overlapping area of ​​each of the third projections and the fourth projection is configured to vary along the first direction.

[0014] Optionally, the nonlinear change regions of the first dielectric layer and the second dielectric layer include: A first edge and a second edge; The first edge is configured to connect the linear change regions of the first dielectric layer and the second dielectric layer respectively, and the second edge is configured to intersect at least one fourth projection at a fifth projection perpendicular to the main surface of the piezoelectric substrate; In which, the second edge is configured to adopt a linear edge and / or a nonlinear edge. When the second edge adopts a linear edge, the angle between the second edge and the first direction is configured to be -45°~+45°. When the second edge adopts a nonlinear edge, the angle between the tangent at any point on the second edge and the first direction is configured to be -45°~+45°.

[0015] A second aspect of the present invention provides a multiplexer, comprising: an elastic wave device as described in any one of the above items.

[0016] The beneficial effects of the present invention are as follows: an elastic wave device and a multiplexer are proposed, by arranging a dielectric layer between a piezoelectric substrate and an IDT electrode, which can cover a partial area of ​​the IDT electrode when projected on a main surface perpendicular to the piezoelectric substrate, and utilizing a linear change region in the dielectric layer in which the area of ​​the projected region on the main surface perpendicular to the piezoelectric substrate changes linearly along a second direction and a nonlinear change region in which the area of ​​the projected region on the main surface perpendicular to the piezoelectric substrate changes linearly along the second direction, so that in-band spurious can be suppressed on a multi-layer composite piezoelectric substrate and the passband performance of the filter can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. 4 is a schematic diagram of a structure of an elastic wave device in this embodiment.

[0018] Figure 2 FIG. 1 is a cross-sectional view of one structure of the elastic wave device in this embodiment at II.

[0019] Figure 3 FIG. 4 is a side view of one structure of the elastic wave device in this embodiment.

[0020] Figure 4FIG. 2 is a second structural diagram of the elastic wave device in this embodiment.

[0021] Figure 5 FIG. 3 is a schematic diagram of the third structure of the elastic wave device in this embodiment.

[0022] Figure 6 FIG. 4 is a schematic diagram of the fourth structure of the elastic wave device in this embodiment.

[0023] Figure 7 FIG. 5 is a schematic diagram of the fifth structure of the elastic wave device in this embodiment.

[0024] Figure 8 FIG. 6 is a sixth structural diagram of the elastic wave device in this embodiment.

[0025] Fig. 9 It is a schematic diagram of the structure of an elastic wave device in a comparative example.

[0026] Fig.10 It is a cross-sectional view of one structure of the elastic wave device in the comparative example taken along line II-II.

[0027] Fig.11 FIG. 1 is a side view of one structure of an elastic wave device in a comparative example.

[0028] Fig.12 FIG. 4 is a schematic diagram showing changes in the Y parameter of the IDT resonator of the elastic wave device of the embodiment and the comparative example.

[0029] Fig.13 FIG. 1 is a schematic diagram showing changes in the real part of the Y parameter of the IDT resonator of the elastic wave device of the embodiment and the comparative example.

[0030] Reference numerals: 1-piezoelectric substrate; 11-multilayer substrate; 12-piezoelectric substrate; 2-IDT electrode layer; 211-first IDT electrode strip; 2111-first bus bar; 2112-first finger strip; 212-second IDT electrode strip; 2121-second bus bar; 2122-second finger strip; 22-first reflector; 23-second reflector; 31-first dielectric layer; 32-second dielectric layer; S1-linear change region; S2-nonlinear change region. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Embodiment 1: like Figure 1-Figure 3 As shown, an elastic wave device comprises: a piezoelectric substrate 1; an IDT electrode layer 2, arranged on the piezoelectric substrate 1; wherein the IDT electrode layer 2 comprises an IDT electrode, a first reflector 22 and a second reflector 23, the first reflector 22 and the second reflector 23 being configured to sandwich the IDT electrode on the main surface of the piezoelectric substrate 1 along a first direction; a dielectric layer, arranged between the piezoelectric substrate 1 and the IDT electrode; wherein the projection of the dielectric layer on the main surface perpendicular to the piezoelectric substrate 1 is configured to cover a portion of the projection of the IDT electrode on the main surface perpendicular to the piezoelectric substrate 1; wherein the dielectric layer comprises a linear change region S1 and a nonlinear change region S2 distributed along a second direction, the linear change region S1 being configured to have a projection area on the main surface perpendicular to the piezoelectric substrate 1 linearly change in the second direction, and the nonlinear change region S2 being configured to have a projection area on the main surface perpendicular to the piezoelectric substrate 1 nonlinearly change in the second direction.

[0033] It should be noted that the traditional elastic wave filter uses a single piezoelectric material as a substrate, and it is inevitable that energy will leak into the inside of the piezoelectric material, resulting in a low Q value. The multi-layer composite substrate can effectively prevent energy from leaking into the inside of the piezoelectric material, improve the Q value and bandwidth, and improve the power capacity and temperature performance. Although the composite substrate improves the performance of the elastic wave device, spurious signals will be formed in the band, affecting the passband performance. In order to solve the above problems, this embodiment provides a dielectric layer between the piezoelectric substrate 1 and the IDT electrode, which can cover part of the IDT electrode area on the main surface perpendicular to the piezoelectric substrate 1. By using the linear change area S1 in the dielectric layer in which the area of ​​the projection area on the main surface perpendicular to the piezoelectric substrate 1 changes linearly along the second direction and the nonlinear change area S2 in which the area of ​​the projection area on the main surface perpendicular to the piezoelectric substrate 1 changes linearly along the second direction, it is possible to suppress in-band spurious signals on the multi-layer composite piezoelectric substrate 1 and improve the passband performance of the filter.

[0034] In a preferred embodiment, the piezoelectric substrate 1 includes: a multilayer substrate 11, which is configured to have at least two layers of substrate in a stacked arrangement; a piezoelectric substrate 12, which is arranged on the multilayer substrate 11; wherein the side of the piezoelectric substrate 12 away from the multilayer substrate 11 is configured as the main surface of the piezoelectric substrate 1.

[0035] In this embodiment, the piezoelectric substrate 1 adopts a multi-layer composite piezoelectric substrate, which is composed of a piezoelectric substrate 12 made of a piezoelectric material and a plurality of substrates with different acoustic impedances stacked on top of each other. In practical applications, the piezoelectric material is lithium tantalate (LiTaO3), but is not limited to lithium tantalate, and may also be lithium niobate (LiNbO3), sapphire, quartz, etc. The multi-layer substrate 11 is not limited to silicon dioxide (SiO2), silicon (Si) and other wafer materials, and may be 2 layers or more than 3 layers.

[0036] In a preferred embodiment, the first reflector 22 and the second reflector 23 are respectively arranged on the first side and the second side of the IDT electrode along the first direction on the main surface of the piezoelectric substrate 1, and are configured as a reflection grid with the elastic wave reflection direction pointing to the IDT electrode. The IDT electrode includes: a first IDT electrode strip 211 and a second IDT electrode strip 212; wherein the first IDT electrode strip 211 includes a first bus bar 2111 and a plurality of first fingers 2112 arranged perpendicular to the first bus bar 2111 on the main surface of the piezoelectric substrate 1, and the second IDT electrode strip 212 includes a second bus bar 2121 and a plurality of second fingers 2122 arranged perpendicular to the second bus bar 2121 on the main surface of the piezoelectric substrate 1; wherein the first bus bar 2111 and the second bus bar 2121 are arranged parallel to each other along the second direction on the main surface of the piezoelectric substrate 1, and the plurality of first fingers 2112 and the plurality of second fingers 2122 are arranged crosswise and parallel to each other along the first direction on the main surface of the piezoelectric substrate 1.

[0037] In this embodiment, the IDT electrode layer 2 is an interdigital transducer (IDT) disposed on the main surface of the piezoelectric substrate 1, and the interdigital transducer is not limited to metal compositions such as Al, Cu, Ag, Au, Pt, and Ti. In practical applications, the first finger 2112 in the first IDT electrode strip 211 and the second finger 2122 in the second IDT electrode strip 212 extend along the second direction (i.e., the x direction), and a plurality of first fingers 2112 and second fingers 2122 are arranged crosswise along the first direction (i.e., the y direction) and are respectively connected to the first bus bar 2111 of the first IDT electrode strip 211 and the second bus bar 2121 of the second IDT electrode strip 212, and the first fingers 2112 and the second fingers 2122 are reflective gratings on the upper and lower sides, which can reflect back the IDT energy, constrain the energy within the IDT, and avoid leakage to the upper and lower ends.

[0038] In a preferred embodiment, the dielectric layer includes: a first dielectric layer 31 and a second dielectric layer 32; wherein the first dielectric layer 31 and the second dielectric layer 32 include a linear change region S1 and a nonlinear change region S2 distributed along a second direction; wherein the linear change region S1 of the first dielectric layer 31 and the second dielectric layer 32 are arranged in parallel along the second direction on the main surface of the piezoelectric substrate 1, and the nonlinear change region S2 of the first dielectric layer 31 and the second dielectric layer 32 are respectively arranged on a side of the first dielectric layer 31 close to the second dielectric layer 32 and a side of the second dielectric layer 32 close to the first dielectric layer 31.

[0039] Furthermore, the two first projections of the linear change region S1 of the first dielectric layer 31 and the second dielectric layer 32 on the main surface perpendicular to the piezoelectric substrate 1 are configured to respectively cover the two second projections of the first bus bar 2111 and the second bus bar 2121 on the main surface perpendicular to the piezoelectric substrate 1. The two third projections of the nonlinear change region S2 of the first dielectric layer 31 and the second dielectric layer 32 on the main surface perpendicular to the piezoelectric substrate 1 are configured to cover partial areas of the fourth projections of the plurality of first fingers 2112 and the plurality of second fingers 2122 arranged in parallel and crossing each other on the main surface perpendicular to the piezoelectric substrate 1.

[0040] In a preferred embodiment, the overlapping area of ​​each of the third projections and the fourth projection is configured to vary along the first direction.

[0041] In this embodiment, a dielectric layer composed of SiO2 is added between the IDT electrode and the piezoelectric material LiTaO3 in the piezoelectric substrate 1. The material of the dielectric layer is not limited to SiN and Al2O3. The dielectric layer is composed of a first dielectric layer 31 and a second dielectric layer 32. The coverage area of ​​the linear change region S1 of the first finger 2112 and the second finger 2122 and the first dielectric layer 31 and the second dielectric layer 32 is a fixed value when it changes in the first direction, and the coverage area of ​​the nonlinear change region S2 of the first finger 2112 and the second finger 2122 and the first dielectric layer 31 and the second dielectric layer 32 is a variable value when it changes in the first direction. This can suppress in-band spurious on the multi-layer composite piezoelectric substrate 1 and improve the passband performance of the filter.

[0042] In a preferred embodiment, the nonlinear change region S2 of the first dielectric layer 31 and the second dielectric layer 32 includes: a first edge and a second edge; wherein the first edge is configured to connect the linear change regions S1 of the first dielectric layer 31 and the second dielectric layer 32 respectively, and the second edge is configured to intersect a fifth projection with at least one fourth projection on a main surface perpendicular to the piezoelectric substrate 1; wherein the second edge is configured to adopt a linear edge and / or a nonlinear edge, when the second edge adopts a linear edge, the angle between the second edge and the first direction is configured to be -45°~+45°, and when the second edge adopts a nonlinear edge, the angle between the tangent at any point on the second edge and the first direction is configured to be -45°~+45°.

[0043] It should be noted that the coverage area of ​​the nonlinear change zone S2 of the first finger 2112, the second finger 2122, the first dielectric layer 31, and the second dielectric layer 32 can change in various forms as it changes in the first direction, for example, first increasing and then decreasing, first decreasing and then increasing, constantly decreasing, or constantly increasing, etc.

[0044] For example, Figure 1 As shown, the second edge of the nonlinear change region S2 of the first dielectric layer 31 and the second dielectric layer 32 adopts a linear edge, the angle between the second edge and the first direction is configured to be -45°~+45°, and the coverage area of ​​the nonlinear change region S2 of the first finger 2112 and the second finger 2122 and the first dielectric layer 31 and the second dielectric layer 32 changes in the manner of first increasing arithmetic difference and then decreasing arithmetic difference when changing along the first direction. In a preferred embodiment, the angle between the second edge and the first direction is configured to be -8° and 8°.

[0045] For example, Figure 4 As shown, the second edge of the nonlinear change region S2 of the first dielectric layer 31 and the second dielectric layer 32 adopts a linear edge, the angle between the second edge and the first direction is configured to be -45°~+45°, and the coverage area of ​​the nonlinear change region S2 of the first finger 2112 and the second finger 2122 and the first dielectric layer 31 and the second dielectric layer 32 changes in the first direction in a manner of first decreasing arithmetic difference and then increasing arithmetic difference. In a preferred embodiment, the angle between the second edge and the first direction is configured to be -8° and 8°.

[0046] For example, Figure 5As shown, the second edge of the nonlinear change area S2 of the first dielectric layer 31 and the second dielectric layer 32 adopts a nonlinear edge, and the angle between the tangent at any point on the second edge and the first direction is configured to be -45°~+45°, and the coverage area of ​​the nonlinear change area S2 of the first finger 2112 and the second finger 2122 and the first dielectric layer 31 and the second dielectric layer 32 changes in the first direction in a manner of first decelerating and then accelerating (i.e., each increase in coverage area is less than the last increase in coverage area in the first direction, and each decrease in coverage area is greater than the last decrease in coverage area in the first direction). In a preferred embodiment, the angle between the tangent at any point on the second edge and the first direction is configured to be -8° and 8°.

[0047] For example, Figure 6 As shown, the second edge of the nonlinear change area S2 of the first dielectric layer 31 and the second dielectric layer 32 adopts a nonlinear edge, and the angle between the tangent at any point on the second edge and the first direction is configured to be -45°~+45°, and the coverage area of ​​the nonlinear change area S2 of the first finger 2112 and the second finger 2122 and the first dielectric layer 31 and the second dielectric layer 32 changes in the first direction in a manner of first decelerating and then accelerating (i.e., each time the coverage area decreases is less than the last increase in the coverage area in the first direction, and each time the coverage area increases is greater than the last decrease in the coverage area in the first direction). In a preferred embodiment, the angle between the tangent at any point on the second edge and the first direction is configured to be -8° and 8°.

[0048] For example, Figure 7 As shown, the second edge of the nonlinear change region S2 of the first dielectric layer 31 and the second dielectric layer 32 adopts a linear edge, the angle between the second edge and the first direction is configured to be -45°~+45°, and the coverage area of ​​the nonlinear change region S2 of the first finger 2112 and the second finger 2122 and the first dielectric layer 31 and the second dielectric layer 32 changes in a manner of decreasing as the first direction changes. In a preferred embodiment, the angle between the second edge and the first direction is configured to be -8° and 8°.

[0049] For example, Figure 8 As shown, the second edge of the nonlinear change region S2 of the first dielectric layer 31 and the second dielectric layer 32 adopts a linear edge, the angle between the second edge and the first direction is configured to be -45°~+45°, and the coverage area of ​​the nonlinear change region S2 of the first finger 2112 and the second finger 2122 and the first dielectric layer 31 and the second dielectric layer 32 changes in a manner of increasing as the first direction changes. In a preferred embodiment, the angle between the second edge and the first direction is configured to be -8° and 8°.

[0050] In the comparative example, Figure 9-11 As shown, an elastic wave device without SiO2 between the IDT electrode layer 2 and the piezoelectric material LiTaO3 in the piezoelectric substrate 1 is provided. In this comparative example, the first finger 2112 in the first IDT electrode strip 211 and the second finger 2122 in the second IDT electrode strip 212 extend along the second direction (i.e., the x direction), and a plurality of first fingers 2112 and second fingers 2122 are arranged crosswise along the first direction (i.e., the y direction) and are respectively connected to the first bus bar 2111 of the first IDT electrode strip 211 and the second bus bar 2121 of the second IDT electrode strip 212. The first fingers 2112 and the second fingers 2122 are reflective gratings on the upper and lower sides, which can reflect back the IDT energy, constrain the energy within the IDT, and avoid leakage to the upper and lower ends.

[0051] like Figure 12-13 As shown, the elastic wave device provided in Example 1 and the elastic wave device provided in the comparative example are used to perform the same filtering task under the same conditions. Fig.12 The solid line and the dotted line are the variation curves of the Y parameter of the IDT resonator in Example 1 and the comparative example, respectively. Fig.13 The solid line and dotted line are the change curves of the real part of the Y parameter of the IDT resonator in Example 1 and the comparative example respectively. Compared with the comparative example, the curve of Example 1 is smoother at 1.88 GHz-1.89 GHz, which suppresses the in-band spurious of the filter, making the passband smoother and the flatness better.

[0052] Embodiment 2: A multiplexer is proposed. The multiplexer includes: the elastic wave device as described above.

[0053] It should be noted that the specific implementation of the multiplexer of the present application is basically the same as the above-mentioned elastic wave device embodiment, which can suppress in-band spurious and improve the passband performance of the filter on a multi-layer composite piezoelectric substrate, and will not be repeated here.

[0054] In the description of the embodiments of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "center", "top", "bottom", "top", "bottom", "inside", "outside", "inner side", "outer side" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. Among them, "inside" refers to an internal or enclosed area or space. "Periphery" refers to the area surrounding a specific component or a specific area.

[0055] In the description of the embodiments of the present invention, the terms "first", "second", "third", and "fourth" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", "third", and "fourth" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0056] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", and "assemble" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0057] In the description of the embodiments of the present invention, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0058] In the description of the embodiments of the present invention, it should be understood that "-" and "~" represent a range between two values, and the range includes the endpoints. For example: "AB" represents a range greater than or equal to A and less than or equal to B. "A~B" represents a range greater than or equal to A and less than or equal to B.

[0059] In the description of the embodiments of the present invention, the term "and / or" herein is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " herein generally indicates that the associated objects before and after are in an "or" relationship.

[0060] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An elastic wave device, characterized in that: include: Piezoelectric substrate; An IDT electrode layer is disposed on the piezoelectric substrate; The IDT electrode layer includes an IDT electrode, a first reflector and a second reflector, and the first reflector and the second reflector are configured to sandwich the IDT electrode on the main surface of the piezoelectric substrate along a first direction; A dielectric layer is disposed between the piezoelectric substrate and the IDT electrode; wherein the projection of the dielectric layer on the main surface perpendicular to the piezoelectric substrate is configured to cover a portion of the projection of the IDT electrode on the main surface perpendicular to the piezoelectric substrate; In which, the dielectric layer includes a linear change zone and a nonlinear change zone distributed along the second direction, the linear change zone is configured so that the projected area on the main surface perpendicular to the piezoelectric substrate changes linearly along the second direction, and the nonlinear change zone is configured so that the projected area on the main surface perpendicular to the piezoelectric substrate changes nonlinearly along the second direction.

2. The elastic wave device according to claim 1, wherein: The piezoelectric substrate comprises: A multi-layer substrate configured to have at least two substrate layers arranged in a stacked manner; A piezoelectric substrate is disposed on the multi-layer substrate; wherein a side of the piezoelectric substrate away from the multi-layer substrate is configured as a main surface of the piezoelectric substrate.

3. The elastic wave device according to claim 1, wherein: The IDT electrode comprises: a first IDT electrode strip and a second IDT electrode strip; The first IDT electrode strip includes a first bus bar and a plurality of first fingers disposed perpendicularly to the first bus bar on the main surface of the piezoelectric substrate, and the second IDT electrode strip includes a second bus bar and a plurality of second fingers disposed perpendicularly to the second bus bar on the main surface of the piezoelectric substrate; The first bus bar and the second bus bar are arranged in parallel along the second direction on the main surface of the piezoelectric substrate, and the plurality of first fingers and the plurality of second fingers are arranged in parallel and cross each other along the first direction on the main surface of the piezoelectric substrate.

4. The elastic wave device according to claim 1, wherein: The first reflector and the second reflector are respectively disposed on a first side and a second side of the IDT electrode along a first direction on the main surface of the piezoelectric substrate, and are configured as reflection gratings whose elastic wave reflection direction points to the IDT electrode.

5. The elastic wave device according to claim 3, wherein: The dielectric layer comprises: a first dielectric layer and a second dielectric layer; Wherein, the first dielectric layer and the second dielectric layer include a linear change region and a nonlinear change region distributed along the second direction; The linear change regions of the first dielectric layer and the second dielectric layer are arranged in parallel along a second direction on the main surface of the piezoelectric substrate, and the nonlinear change regions of the first dielectric layer and the second dielectric layer are respectively arranged on a side of the first dielectric layer close to the second dielectric layer and a side of the second dielectric layer close to the first dielectric layer.

6. The elastic wave device according to claim 5, wherein: Two first projections of the linear change regions of the first dielectric layer and the second dielectric layer on a main surface perpendicular to the piezoelectric substrate are configured to respectively cover two second projections of the first bus bar and the second bus bar on a main surface perpendicular to the piezoelectric substrate.

7. The elastic wave device according to claim 5, wherein: The two third projections of the nonlinear change zones of the first dielectric layer and the second dielectric layer on the main surface perpendicular to the piezoelectric substrate are configured to cover partial areas of the fourth projections of the plurality of first fingers and the plurality of second fingers arranged in parallel and crossing each other on the main surface perpendicular to the piezoelectric substrate.

8. The elastic wave device according to claim 7, wherein: The overlapping area of ​​each of the third projections and the fourth projection is configured to change along the first direction.

9. The elastic wave device according to claim 7, wherein: The nonlinear change regions of the first dielectric layer and the second dielectric layer include: A first edge and a second edge; The first edge is configured to connect the linear change regions of the first dielectric layer and the second dielectric layer respectively, and the second edge is configured to intersect at least one fourth projection at a fifth projection perpendicular to the main surface of the piezoelectric substrate; In which, the second edge is configured to adopt a linear edge and / or a nonlinear edge. When the second edge adopts a linear edge, the angle between the second edge and the first direction is configured to be -45°~+45°. When the second edge adopts a nonlinear edge, the angle between the tangent at any point on the second edge and the first direction is configured to be -45°~+45°.

10. A multiplexer, characterized in that: include: An elastic wave device as claimed in any one of claims 1 to 9.

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