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

Abstract

The invention provides an elastic wave device capable of suppressing a spurious mode and having a tuning characteristic, and belongs to the technical field of communication electronic devices, the elastic wave device 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 invention 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 progress of MEMS technology, elastic wave devices involving interdigital transducers are widely used in various terminal devices due to their advantages such as small size, low cost and excellent performance. Taking RF filters as an example, as elastic wave devices involving interdigital transducers, they are extremely important components in RF front ends. Key parameters such as spurious modes, quality factors and electromechanical coupling coefficients of elastic wave devices have a decisive influence on the performance of RF filters.

[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 respectively connected to positive and negative electrical signals. 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 the mass loading effect, which makes the sound waves in the film have sound velocity differences in multiple regions. For example, the wave velocity distribution between the bus bar and the transducer is discontinuous, which makes the sound waves reflect and scatter 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 Figure 3b In addition, high-speed 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, a longitudinal leakage body wave mode (SM3) appears at 1125MHz.

[0004] The above-mentioned various undesirable acoustic wave modes have a serious impact on the performance of elastic wave devices, deteriorating the flatness, insertion loss and rectangular coefficient of the filter passband. Therefore, in the application of elastic wave devices, it is particularly important to suppress spurious modes. Summary of the invention

[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 stray modes and having tuning characteristics comprises a piezoelectric substrate and an excitation electrode, wherein the excitation electrode is 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, and an etching window is provided on the surface of the piezoelectric film, wherein 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 regions and the regions between the apertures are resonance regions.

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

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

[0012] Furthermore, the L-shaped etching windows are 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 windows arranged in the area between the apertures does not exceed the aperture length, and the width of the L-shaped etching windows arranged in the area between the apertures does not exceed the distance between the apertures.

[0013] Furthermore, reflection devices are arranged on both sides of the IDT, and the reflection devices are reflector grid arrays, ball arrays, or reflection slot air boundaries, or hole arrays.

[0014] Furthermore, 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.

[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 etching window does not exceed one wavelength in the bulk piezoelectric material, and the depth of the etching window does not exceed the thickness of the piezoelectric layer in the multi-layer composite material.

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

[0018] 1. The present invention sets a T-shaped etching window, and the aperture at least partially buries 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 sound waves excited in the gap area from generating stray modes along the aperture direction. In addition, the T-shaped etching window can change the electric field distribution, induce the target sound 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 transducer remain unchanged.

[0019] 2. The present invention reduces the thickness of the piezoelectric layer between the apertures by setting an L-shaped etching window, reduces the coupling effect between the acoustic wave mode in the piezoelectric body and the electric field, thereby significantly suppressing the body wave, and creates a reflection boundary in the gap area to prevent the undesirable acoustic waves excited in the gap area from generating transverse modes 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 transducer remain unchanged.

[0020] 3. The present invention is applicable to various types of acoustic wave devices, especially for the requirements of low insertion loss, small ripple and large bandwidth of high-performance filters. The present invention has a significant optimization effect on the passband frequency response characteristics of elastic wave devices, so that related MEMS products can be applied in a variety of terminal devices such as mobile communications, smart homes and automobile manufacturing, as well as base stations and other wider fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present invention, the following will briefly introduce the drawings required for the description of the specific embodiments. The drawings described below are example drawings of the elastic wave device involving the interdigital transducer described above. Obviously, the drawings described below are only exemplary, and for ordinary technicians in this field, other embodiment drawings can be derived from the provided drawings without creative work.

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

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

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

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

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

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

[0028] Figure 4 is a comparison diagram of two elastic wave device structures provided by the present invention;

[0029] Figure 5 It 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 present invention;

[0030] Figure 6 A frequency response characteristic diagram of a T-shaped elastic wave device capable of suppressing spurious modes and having tuning characteristics provided in Example 1 of the present invention;

[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 invention;

[0032] Figure 8 It 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 present invention;

[0033] Fig. 9 A frequency response characteristic diagram of an L-shaped elastic wave device capable of suppressing spurious modes and having tuning characteristics provided in Example 2 of the present invention;

[0034] Fig.10 The frequency-etching depth variation relationship of an L-shaped elastic wave device capable of suppressing spurious modes and having tuning characteristics provided in Example 2 of the present invention;

[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 patent will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present patent are shown in the accompanying drawings, it should be understood that the present patent 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 patent and to fully convey the scope of the present patent to those skilled in the art. It should be noted that the embodiments in the present patent and the features in the embodiments can be combined with each other without conflict. The present patent 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 capable of suppressing stray modes and having tuning characteristics, comprising a piezoelectric substrate and an excitation electrode, wherein the excitation electrode is disposed on the upper surface of the piezoelectric substrate, and the piezoelectric substrate comprises a composite substrate 1 and a piezoelectric film 2. It should be noted that the composite substrate 1 is disposed at the bottom of the piezoelectric film 2. The schematic diagram of the structure 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 present invention 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, and reflection devices are arranged on both sides of the interdigital transducer 31. The reflection device is a reflector (grid array, ball array), or a reflection groove (air boundary, hole array). In this embodiment, the reflection device is a reflection grid 33, and the reflection grid 33 is 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, and 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-tooth-shaped 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 bar with multiple comb-tooth-shaped 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 bar connecting the transducers 31 on the same side to transmit different electrical excitations to the transducers 31 at both ends, and the bus bar 32 is vertically connected to one end of the transducer 31, and the 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 section of adjacent comb-toothed metal strips is the aperture, and the piezoelectric material covered by the aperture area and the area between the apertures is the resonance area. Between the end of the comb-toothed metal strip and the bus bar, there is a metal horizontal strip that runs through the comb-toothed metal strip on the same side. The area not covered by the metal horizontal strip is the gap area. The metal horizontal strips are any number, parallel to the bus bar and run through the comb-toothed metal strip on the same side, which are used to restrict the diffusion of sound 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 sound 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 etching windows 41 are 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. At least a portion of the interdigital transducers 31 on the surface of the piezoelectric substrate is placed in the T-shaped etching window 41. T-shaped etching windows 41 are arranged on the upper surface of the piezoelectric substrate in the preset aperture area and the gap area. At least a portion of the interdigital transducers 31 is placed in the T-shaped etching windows 41 on the upper surface of the piezoelectric substrate. 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. The size of the etching window arranged in the gap area does not exceed the distance between adjacent interdigital transducers 31 on the same side, and at the same time, 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 present invention 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 avoid the undesirable sound waves excited in the gap area from generating stray modes SM2 along the aperture direction; in addition, the T-shaped etching window 41 can change the electric field distribution, induce the target sound wave mode from the surface to the body to form a body-like wave, and increase the wave speed, so as to control the etching depth to achieve positive adjustment of the resonance 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 etching window does not exceed one wavelength in the bulk piezoelectric material, and the depth of the etching window does not exceed the thickness of the piezoelectric layer in the multi-layer composite material.

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

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

[0046] Figure 6 The frequency response characteristic diagram of the elastic wave device under the size and setting of this embodiment, the frequency of the resonance point of the main mode 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 frequency 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 Figure 8-Figure 10 As shown, in this embodiment, the etching window adopts an L-shaped etching window 42, and the L-shaped etching window 41, the excitation electrode and the piezoelectric substrate together constitute an L-shaped structure elastic wave device; 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, and 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. 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 7The schematic diagram of the structure of the L-shaped elastic wave device provided by the present invention. An L-shaped etching window 42 is set on the upper surface of the piezoelectric substrate between the apertures and the gap area, the length of the L-shaped etching window 42 set between the apertures does not exceed the aperture length, the width of the L-shaped etching window 42 set between the apertures does not exceed the distance between the apertures, and the size of the etching window set in the gap area does not exceed the distance between the adjacent transducers 31 on the same side, and at the same time, 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 between the apertures 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.

[0050] The present invention reduces the thickness of the piezoelectric layer between the apertures and reduces the coupling effect between the acoustic wave mode and the electric field in the piezoelectric body by setting an L-shaped etching window 42, thereby significantly suppressing SM1 and SM3, and creating 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 region is the same as the gap size, with a depth of 1.07 μm; Fig. 9 The frequency response characteristic diagram of the elastic wave device size and setting in this embodiment, the frequency of the main mode resonance point is 664MHz, and the frequency of the anti-resonance point is 692MHz. Compared with the prior art, the frequency at the resonance point is reduced by 106MHz, SM2 is basically eliminated, and SM1 and SM3 are significantly suppressed; Fig.10 This is the relationship between the series resonance frequency 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 of this article are only used to illustrate the technical solution of this patent, but the implementation of this patent is not limited by the above content. Any other changes, modifications, substitutions, combinations, etc. that do not deviate from the innovative essence and principles of this patent are included in the protection scope of this patent. For those skilled in the art, the specific meanings of the above terms in the patent can be understood according to the specific circumstances.

Claims

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

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

4. The elastic wave device capable of suppressing spurious modes and having tuning characteristics according to claim 2, characterized in that: Between the end of the comb-tooth-shaped metal strip and the bus bar, a metal horizontal strip is provided which passes through the comb-tooth-shaped metal strip on the same side, and the area not covered by the metal horizontal strip is a gap area.

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

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

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