Elastic wave device capable of suppressing spurious mode and having tuning characteristic

Abstract

The utility model provides an elastic wave device capable of suppressing a spurious mode and having tuning characteristics, which belongs to the technical field of communication electronic devices, and comprises a piezoelectric substrate and an excitation electrode, the excitation electrode is arranged on the upper surface of the piezoelectric substrate, the piezoelectric substrate comprises a composite substrate and a piezoelectric film, and the composite substrate is arranged on the piezoelectric film. The excitation electrode at least comprises an interdigital transducer and a bus bar, the surface of the piezoelectric film is provided with etching windows, the etching windows comprise a T-shaped etching window and an L-shaped etching window, and the T-shaped etching window and the L-shaped etching window form a T-shaped structure elastic wave device and an L-shaped structure elastic wave device respectively. The etching window realizes suppression of a stray mode through matching of acoustic impedance between interfaces, optimization of electric field distribution, manufacturing of a reflection boundary and other schemes, the resonance frequency band of a target mode can be adjusted by controlling the etching depth, and the method is suitable for multiple types of acoustic wave devices, and especially meets the requirements of low insertion loss, small ripple and large bandwidth of a high-performance filter.

Description

Technical Field

[0001] The utility model belongs to the technical field of communication electronic devices, and in particular relates to an elastic wave device capable of suppressing spurious modes and having tuning characteristics. Background Art

[0002] With the development and advancement of MEMS technology, elastic wave devices using interdigital transducers (IDTs) have become widely used in various terminal devices due to their advantages such as small size, low cost, and excellent performance. For example, RF filters, as an IDT-based elastic wave device, are extremely important components in RF front-ends. Key parameters such as spurious modes, quality factor, and electromechanical coupling coefficient of elastic wave devices have a decisive impact on RF filter performance.

[0003] Figure 1a and Figure 1b It is a top view and a cross-sectional view of an elastic wave device involving an interdigital transducer in the prior art, including a piezoelectric substrate, and an excitation electrode and a reflection grid arranged on the upper surface of the piezoelectric substrate. The piezoelectric substrate is a multi-layer structure, which includes a piezoelectric film and a composite substrate from top to bottom. The excitation electrode is composed of an interdigital transducer and a bus bar. The bus bars at both ends are connected to positive and negative electrical signals respectively. The interdigital transducer connected to the bus bar generates electrical excitation to cause the piezoelectric film to produce an inverse piezoelectric effect. When the frequency of the excitation signal is consistent with the mechanical resonance frequency, the device resonates, and sound waves propagate in the piezoelectric film. The frequency response characteristic admittance diagram of the elastic wave device shown in Figure 1 is as follows. Figure 2 There are many kinds of sound waves in the piezoelectric film, and some of them will couple under certain conditions and at certain frequencies, such as Figure 3a As shown in the displacement vibration mode, the Rayleigh coupled wave mode (SM1) of the body wave is distributed at 590MHz to the left of the resonance point; the arrangement of the excitation electrodes on the surface of the piezoelectric layer leads to a mass loading effect, which causes the sound waves in the film to have sound velocity differences in multiple regions. For example, the wave velocity distribution between the bus bar and the transducer is discontinuous, which causes the sound waves to be reflected and scattered in the aperture direction, and finally forms a transverse sound wave mode (SM2), which is located in the resonance range of 770MHz to 810MHz, as shown in FIG. Figure 3b In addition, high-velocity body waves can cross the interface difference between different materials and form an acoustic path that leaks to the substrate, as shown in Figure 3c As shown in the displacement vibration mode, the longitudinal leakage body wave mode (SM3) appears at 1125MHz.

[0004] These various undesirable acoustic modes severely impact the performance of elastic wave devices, degrading the filter's passband flatness, insertion loss, and squareness factor. Therefore, suppressing spurious modes is crucial in elastic wave device applications. Utility Model Content

[0005] To solve the above problems, the present invention provides an elastic wave device that can suppress spurious modes and has tuning characteristics. The radio frequency device can achieve clutter suppression and frequency shifting functions, and can have comprehensive performance such as a flatter passband, lower insertion loss and better rectangular coefficient.

[0006] The present invention adopts the following technical solutions to solve the above problems:

[0007] An elastic wave device capable of suppressing spurious modes and having tuning characteristics comprises a piezoelectric substrate and an excitation electrode, the excitation electrode being disposed on the upper surface of the piezoelectric substrate. The piezoelectric substrate comprises a composite substrate and a piezoelectric film. The excitation electrode comprises at least an interdigital transducer and a bus bar. An etching window is provided on the surface of the piezoelectric film. The etching window comprises a T-shaped etching window and an L-shaped etching window.

[0008] Furthermore, the IDT includes two groups of multiple comb-tooth-shaped metal strips arranged in an interlaced manner, and the bus bar includes a bus bar with two ends connecting the multiple comb-tooth-shaped metal strips.

[0009] Furthermore, the overlapping sections of the adjacent comb-shaped metal strips are apertures, and the piezoelectric material covered by the aperture region and the region between the apertures is a resonance region.

[0010] Furthermore, a metal horizontal bar is provided between the end of the comb-tooth-shaped metal bar and the bus bar, passing through the comb-tooth-shaped metal bar on the same side, and the area not covered by the metal horizontal bar is the gap area.

[0011] Furthermore, the T-shaped etched window is arranged on the upper surface of the piezoelectric substrate in the preset aperture area and the gap area, the length of the T-shaped etched window arranged in the preset aperture area does not exceed the aperture length, the width of the T-shaped etched window arranged in the preset aperture area is not less than the aperture width, and at least a portion of the interdigital transducer on the surface of the piezoelectric substrate is placed in the T-shaped etched window.

[0012] Furthermore, the L-shaped etching window is arranged on the upper surface of the piezoelectric substrate in the area between the apertures and the gap area, the length of the L-shaped etching window arranged in the area between the apertures does not exceed the aperture length, and the width of the L-shaped etching window arranged in the area between the apertures does not exceed the distance between the apertures.

[0013] Furthermore, reflecting devices are provided on both sides of the IDT. The reflecting devices are reflectors or reflecting slots. The reflectors include grid array reflectors and ball array reflectors. The reflecting slots include air boundary reflecting slots and hole array reflecting slots.

[0014] Furthermore, the piezoelectric substrate is a bulk piezoelectric material or a multi-layer composite material, and the excitation electrode and the reflective device are a single-layer material or a multi-layer material stack.

[0015] Furthermore, the etching depths of the etching windows in different areas are the same depth or a combination of multiple depths.

[0016] Furthermore, the depth of the etched window does not exceed one wavelength in the bulk piezoelectric material, and the depth of the etched window does not exceed the thickness of the piezoelectric layer in the multilayer composite material.

[0017] The beneficial effects of the present invention are:

[0018] 1. The present invention employs a T-shaped etched window, with the aperture at least partially embedded in the piezoelectric layer, to achieve acoustic impedance matching between different interfaces within the resonator. This creates a reflective boundary in the gap region, preventing undesirable acoustic waves excited in the gap region from generating spurious modes along the aperture direction. Furthermore, the T-shaped etched window modulates the electric field distribution, inducing the target acoustic wave mode from the surface into the body, forming a bulk-like wave. This increases the wave velocity, thereby controlling the etch depth to achieve positive adjustment of the resonant frequency band while maintaining the basic transducer parameters.

[0019] 2. By providing L-shaped etched windows, the present invention reduces the thickness of the piezoelectric layer between the apertures, thereby reducing the coupling between the acoustic wave modes within the piezoelectric body and the electric field. This significantly suppresses body waves and creates a reflective boundary in the gap region, preventing undesirable acoustic waves excited in the gap region from generating transverse modes along the aperture direction. Furthermore, the etched windows between the apertures extend the acoustic wave transmission path between the excitation ports, reducing the operating frequency. Thus, while maintaining the basic transducer parameters, the etch depth can be controlled to achieve reverse adjustment of the resonant frequency band.

[0020] 3. This utility model is applicable to a wide range of acoustic wave devices, especially high-performance filters requiring low insertion loss, minimal ripple, and wide bandwidth. This utility model significantly optimizes the passband frequency response characteristics of elastic wave devices, enabling the application of related MEMS products in a wide range of terminal devices, including mobile communications, smart homes, and automotive manufacturing, as well as base stations, in a wide range of fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To more clearly illustrate the specific embodiments of the present invention, the following briefly describes the drawings required for describing the specific embodiments. The drawings described below are exemplary diagrams of the elastic wave device involving the interdigital transducer described above. Obviously, the drawings described below are merely illustrative, and those skilled in the art can, without inventive effort, derive other exemplary embodiments from the provided drawings.

[0022] Figure 1a It is a schematic top view of an elastic wave device involving an interdigital transducer in the prior art;

[0023] Figure 1b It is a cross-sectional schematic diagram of an elastic wave device involving an interdigital transducer in the prior art;

[0024] Figure 2 This is a frequency response characteristic diagram of an elastic wave device involving an interdigital transducer in the prior art;

[0025] Figure 3a This is a spurious mode SM1 vibration shape diagram of an elastic wave device involving an interdigital transducer in the prior art;

[0026] Figure 3b This is a spurious mode SM2 vibration shape diagram of an elastic wave device involving an interdigital transducer in the prior art;

[0027] Figure 3c This is a spurious mode SM3 vibration shape diagram of an elastic wave device involving an interdigital transducer in the prior art;

[0028] Figure 4 This is a comparison diagram of the two elastic wave device structures provided by the utility model;

[0029] Figure 5 This is a schematic diagram of the structure of a T-shaped elastic wave device that can suppress spurious modes and has tuning characteristics, provided by the utility model;

[0030] Figure 6 This is a frequency response characteristic diagram of a T-shaped elastic wave device that can suppress spurious modes and has tuning characteristics, provided in Example 1 of the present utility model;

[0031] Figure 7 The frequency-etching depth variation relationship of a T-shaped elastic wave device capable of suppressing spurious modes and having tuning characteristics provided in Example 1 of the present utility model;

[0032] Figure 8 This is a schematic diagram of the structure of an L-shaped elastic wave device that can suppress spurious modes and has tuning characteristics, provided by the utility model;

[0033] Figure 9 This is a frequency response characteristic diagram of an L-shaped elastic wave device that can suppress spurious modes and has tuning characteristics, provided in Example 2 of the present utility model;

[0034] Figure 10 The frequency-etching depth variation relationship of an L-shaped elastic wave device that can suppress spurious modes and has tuning characteristics provided in Example 2 of the present utility model;

[0035] In the figure, 1-composite substrate; 2-piezoelectric film; 31-interdigital transducer; 32-bus bar; 33-reflection grating; 41-T-type etching window; 42-L-type etching window; SM1-bulk wave-like Rayleigh coupled wave mode; SM2-transverse acoustic wave mode; SM3-longitudinal leakage bulk wave mode. DETAILED DESCRIPTION

[0036] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other unless there is a conflict. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0037] like Figure 4 As shown, the present invention provides an elastic wave device that can suppress spurious modes and has tuning characteristics, including a piezoelectric substrate and an excitation electrode. The excitation electrode is placed on the upper surface of the piezoelectric substrate. The piezoelectric substrate includes a composite substrate 1 and a piezoelectric film 2. It should be noted that the composite substrate 1 is located at the bottom of the piezoelectric film 2. The structural diagram is shown in FIG. Figure 1b As shown, Figure 4 、 Figure 5 、 Figure 8 It is not drawn in the figure and does not affect the integrity of the technical solution of this case; the excitation electrode includes at least an interdigital transducer 31 and a bus bar 32, and an etching window is provided on the surface of the piezoelectric film 2, and the etching window includes a T-shaped etching window 41 and an L-shaped etching window 42.

[0038] Example 1

[0039] like Figure 5-Figure 7 As shown, the utility model provides an elastic wave device that can suppress stray modes and has tuning characteristics, including a piezoelectric substrate and an excitation electrode. The excitation electrode is placed on the upper surface of the piezoelectric substrate. The piezoelectric substrate includes a composite substrate 1 and a piezoelectric film 2. The excitation electrode includes at least an interdigital transducer 31 and a bus bar 32. Reflection devices are provided on both sides of the interdigital transducer 31. The reflection devices are reflectors (grid arrays, ball arrays) or reflection grooves (air boundaries, hole arrays). In this embodiment, the reflection devices are reflection grids 33, and the reflection grids 33 are distributed on both sides of the excitation electrode; an etching window is provided on the surface of the piezoelectric film 2. In this embodiment, the etching window adopts a T-shaped etching window 41. The T-shaped etching window 41, the excitation electrode and the piezoelectric substrate together constitute a T-shaped structure elastic wave device.

[0040] The interdigital transducer 31 includes two groups of multiple comb-toothed metal strips arranged in an interdigital manner, and the ratio of the width of the interdigital transducer 31 to the spacing between the interdigital transducers 31 is in the range of 0.25 to 3; the bus bar 32 includes a bus with multiple comb-toothed metal strips connected at both ends, and the width of the bus bar 32 is much larger than the width of the transducer 31; the bus bar 32 serves as a bus connecting the transducers 31 on the same side to transmit different electrical excitations to the transducers 31 at both ends. The bus bar 32 is vertically connected to one end of the transducer 31, and adjacent transducers 31 are cross-distributed and connected to different electrical signals to generate a potential difference to form an electric field, and resonance occurs under the action of the inverse piezoelectric effect.

[0041] The overlapping sections of adjacent comb-toothed metal strips are the apertures, and the piezoelectric material covered by the aperture area and the area between the apertures is the resonant area. Between the ends of the comb-toothed metal strips and the bus bars, there are metal horizontal strips that pass through the comb-toothed metal strips on the same side. The area not covered by the metal horizontal strips is the gap area. The metal horizontal strips can be any number, parallel to the bus bar and pass through the comb-toothed metal strips on the same side, and are used to constrain the diffusion of acoustic wave energy to both ends; the reflection grid 33 is placed on both sides of the excitation electrode to limit the energy leakage to both sides when the acoustic wave propagates. The material of the reflection grid 33 is the same as that of the excitation electrode, and the ratio of the grid width to the finger width is in the range of 0.2 to 5.

[0042] T-shaped etched windows 41 are provided on the upper surface of the piezoelectric substrate in the preset aperture region and the gap region. The length of the T-shaped etched windows 41 provided in the preset aperture region does not exceed the aperture length, and the width of the T-shaped etched windows 41 provided in the preset aperture region is not less than the aperture width. At least a portion of the interdigital transducers 31 on the surface of the piezoelectric substrate is placed in the T-shaped etched windows 41. T-shaped etched windows 41 are provided on the upper surface of the piezoelectric substrate in the preset aperture region and the gap region, and at least a portion of the interdigital transducers 31 is placed in the T-shaped etched windows 41 on the upper surface of the piezoelectric substrate. The length of the T-shaped etched windows 41 provided in the preset aperture region does not exceed the aperture length, and the width of the T-shaped etched windows 41 provided in the preset aperture region is not less than the aperture width. The size of the etched windows provided in the gap region does not exceed the distance between adjacent interdigital transducers 31 on the same side, and does not exceed the distance between the end of the comb-shaped metal strip and the bus bar 32. The etching depth of the etching window in different areas is the same depth or a combination of multiple depths. The etching window depth in the aperture area is less than the thickness of the piezoelectric film 2, and the etching window depth in the gap area does not exceed the thickness of the piezoelectric film 2. The utility model sets a T-shaped etching window 41, and the aperture is at least partially buried in the piezoelectric layer to match the acoustic impedance between different interfaces in the resonator, and creates a reflection boundary in the gap area to prevent the undesirable acoustic waves excited in the gap area from generating a stray mode SM2 along the aperture direction; in addition, the T-shaped etching window 41 can change the electric field distribution, induce the target acoustic wave mode from the surface to the body to form a body wave, and increase the wave speed, thereby controlling the etching depth to achieve positive adjustment of the resonant frequency band under the premise that the basic parameters of the interdigital transducer 31 remain unchanged.

[0043] The piezoelectric substrate is a bulk piezoelectric material or a multi-layer composite material, the excitation electrode and the reflector device are a single-layer material or a multi-layer material stack, the depth of the etched window does not exceed one wavelength in the bulk piezoelectric material, and the depth of the etched window does not exceed the thickness of the piezoelectric layer in the multi-layer composite material.

[0044] The piezoelectric film 2 can be made of materials such as LiNbO3, LiTaO3, AlN, ZnO, PZT, quartz, or a piezoelectric material doped with a modifying element such as Sc. The piezoelectric film 2 is fabricated by sputtering or evaporation. The excitation electrode and reflector 33 are single-layer or multi-layer stacks, and can be fabricated by sputtering or evaporation using metals such as Al, Pt, Cu, Au, Ti, Ni, Cr, W, Ag, Pd, Co, and Mn, or alloys containing at least one of these metals.

[0045] In this embodiment, the piezoelectric substrate is a composite substrate composed of a piezoelectric film 2 made of LiTaO3 material, and the thickness of the piezoelectric film 2 is 1.07 μm. The excitation electrode and reflector 33 are a stack of two layers of Al and Cu metal materials, with Cu disposed on the upper surface of the piezoelectric substrate and Al disposed on the upper surface of Cu. The thickness of the stack is 400 nm, and the thickness ratio of Al to Cu is 3:1. The width of the transducer 31 is 1 μm, the ratio of the width of the transducer 31 to the spacing between the transducers 31 is 1, the aperture length is 52 μm, the ratio of the grid width to the finger width is 1, the gap is 2 μm, the etching window size of the preset aperture area is the same as the aperture size, with a depth of 300 nm, and the etching window size of the gap area is the same as the gap size, with a depth of 0 nm.

[0046] Figure 6 This is the frequency response characteristic diagram of the elastic wave device under the size and setting of this embodiment. The frequency of the main mode resonance point is 844MHz, the frequency of the anti-resonance point is 890MHz, and Q max Compared with the existing technology, the frequency at the resonance point is increased by 74MHz, the bandwidth is increased by 6MHz, and the Q max 1501 was added, SM2 was basically eliminated, and SM1 and SM3 remained unchanged; Figure 7 This is the relationship between the series resonance frequencies of the T-shaped window at different etching depths described in the embodiment of the present invention. As the depth increases, the resonance frequency continues to increase.

[0047] Example 2

[0048] like Figures 8-10 As shown, in this embodiment, an L-shaped etched window 42 is used as the etched window. The L-shaped etched window 41, the excitation electrode, and the piezoelectric substrate together form an L-shaped elastic wave device. The L-shaped etched window 42 is disposed on the upper surface of the piezoelectric substrate in the region between the apertures and the gap region. The length of the L-shaped etched window 42 disposed in the region between the apertures does not exceed the aperture length, and the width of the L-shaped etched window 42 disposed in the region between the apertures does not exceed the distance between the apertures. Other technical features are the same as those in Example 1.

[0049] The difference between this embodiment and embodiment 1 is that the L-shaped etching window 42 replaces the T-shaped etching window 41. Figure 7Schematic diagram of the L-shaped elastic wave device provided by the present invention. L-shaped etched windows 42 are provided on the upper surface of the piezoelectric substrate between the apertures and in the gap region. The length of the L-shaped etched windows 42 provided between the apertures does not exceed the aperture length, the width of the L-shaped etched windows 42 provided between the apertures does not exceed the distance between the apertures, and the size of the etched windows provided in the gap region does not exceed the distance between adjacent interdigitated transducers 31 on the same side, and does not exceed the distance between the end of the comb-shaped metal strip and the bus bar 32. The etched windows have a uniform depth or a combination of multiple depths in different regions. The depth of the etched windows between the apertures is less than the thickness of the piezoelectric film 2, and the depth of the etched windows in the gap region does not exceed the thickness of the piezoelectric film 2.

[0050] The utility model reduces the thickness of the piezoelectric layer between the apertures by setting an L-shaped etching window 42, reduces the coupling effect between the acoustic wave mode and the electric field in the piezoelectric body, thereby significantly suppressing SM1 and SM3, and creates a reflection boundary in the gap area to avoid the undesirable acoustic waves excited in the gap area from generating SM2 along the aperture direction; in addition, the etching window between the apertures extends the acoustic wave transmission path between the excitation ports, which can reduce the operating frequency, thereby controlling the etching depth to achieve reverse adjustment of the resonant frequency band under the premise that the basic parameters of the interdigital transducer 31 remain unchanged.

[0051] In this embodiment, the etching window size between the apertures is the same as the size between the apertures, with a depth of 550 nm, and the etching window size in the gap area is the same as the gap size, with a depth of 1.07 μm; Figure 9 This is the frequency response characteristic diagram for the elastic wave device dimensions and configuration described in this embodiment. The main mode resonant frequency is 664 MHz, and the antiresonant frequency is 692 MHz. Compared with the prior art, the resonant frequency is reduced by 106 MHz, SM2 is essentially eliminated, and SM1 and SM3 are significantly suppressed. Figure 10 This is the relationship between the series resonance frequencies of the L-shaped window at different etching depths described in the embodiment of the present invention. As the depth increases, the resonance frequency continues to decrease.

[0052] It should be noted that the content and exemplary embodiments herein are intended only to illustrate the technical solutions of this patent. However, the implementation of this patent is not limited by the foregoing content. Any changes, modifications, substitutions, and combinations that do not deviate from the innovative essence and principles of this patent are included within the scope of protection of this patent. Those skilled in the art will understand the specific meanings of the above terms in the patent based on the specific circumstances.

Claims

1. An elastic wave device capable of suppressing spurious modes and having tunable characteristics, comprising a piezoelectric substrate and an excitation electrode, characterized in that: The excitation electrode is placed on the upper surface of a piezoelectric substrate, the piezoelectric substrate comprises a composite substrate (1) and a piezoelectric film (2), the excitation electrode comprises at least an interdigital transducer (31) and a bus bar (32), and an etching window is provided on the surface of the piezoelectric film (2), the etching window comprising a T-shaped etching window (41) and an L-shaped etching window (42).

2. The elastic wave device capable of suppressing spurious modes and having tunable characteristics according to claim 1, characterized in that: The interdigital transducer (31) comprises two groups of multiple comb-tooth-shaped metal strips arranged in a staggered manner, and the bus bar (32) comprises a bus bar with two ends connected to the multiple comb-tooth-shaped metal strips.

3. The elastic wave device capable of suppressing spurious modes and having tunable characteristics according to claim 2, characterized in that: The overlapping sections of the adjacent comb-shaped metal strips are apertures, and the piezoelectric material covered by the aperture region and the region between the apertures is a resonance region.

4. The elastic wave device capable of suppressing spurious modes and having tunable characteristics according to claim 2, characterized in that: Between the ends of the comb-tooth-shaped metal strips and the busbars, there are metal horizontal strips that pass through the comb-tooth-shaped metal strips on the same side, and the area not covered by the metal horizontal strips is the gap area.

5. The elastic wave device capable of suppressing spurious modes and having tunable characteristics according to claim 4, characterized in that: The T-shaped etching window (41) is arranged on the upper surface of the piezoelectric substrate in the preset aperture area and the gap area, the length of the T-shaped etching window (41) arranged in the preset aperture area does not exceed the aperture length, the width of the T-shaped etching window (41) arranged in the preset aperture area is not less than the aperture width, and at least a portion of the interdigital transducer (31) on the surface of the piezoelectric substrate is placed in the T-shaped etching window (41).

6. The elastic wave device capable of suppressing spurious modes and having tunable characteristics according to claim 4, characterized in that: The L-shaped etching window (42) is arranged on the upper surface of the piezoelectric substrate in the area between the apertures and the gap area, the length of the L-shaped etching window (42) arranged in the area between the apertures does not exceed the aperture length, and the width of the L-shaped etching window (42) arranged in the area between the apertures does not exceed the distance between the apertures.

7. The elastic wave device capable of suppressing spurious modes and having tunable characteristics according to claim 1, characterized in that: Reflection devices are provided on both sides of the interdigital transducer (31), wherein the reflection devices are reflectors or reflection slots, wherein the reflectors include grid array reflectors and ball array reflectors, and wherein the reflection slots include air boundary reflection slots and hole array reflection slots.

8. The elastic wave device capable of suppressing spurious modes and having tunable characteristics according to claim 7, characterized in that: The piezoelectric substrate is a bulk piezoelectric material or a multi-layer composite material, and the excitation electrode and the reflection device are a single-layer material or a multi-layer material stack.

9. The elastic wave device capable of suppressing spurious modes and having tunable characteristics according to any one of claims 1 to 8, characterized in that: The etching depths of the etching windows in different areas are the same depth or a combination of multiple depths.

10. The elastic wave device capable of suppressing spurious modes and having tunable characteristics according to claim 8, characterized in that: The depth of the etched window does not exceed one wavelength in bulk piezoelectric material, and the depth of the etched window does not exceed the thickness of the piezoelectric layer in a multilayer composite material.

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