Elastic wave device

Abstract

The present invention provides an elastic wave device, which is provided with a patterned functional regulation layer having interdigital grooves and / or window grooves, and can effectively adjust the velocity profile curve and energy integral of elastic waves, thereby weakening or suppressing the excitation of transverse spurious modes, which is beneficial for the resonator and / or filter to achieve a flat passband, reduce the insertion loss, improve the rectangularity and sideband steepness, simplify the interdigital electrode structure. At the same time, the functional regulation layer with high sound velocity and high Young's modulus helps to improve the temperature stability of the device structure. In addition, the functional regulation layer also has the advantages of protecting the metal interdigital electrodes and surface passivation, and can improve the heat dissipation performance and lifespan of the elastic wave device, thereby increasing the power capacity.

Description

Technical Field

[0001] The present invention belongs to the field of microelectronic devices and relates to an elastic wave device. Background Art

[0002] An important component for a mobile terminal to achieve communication is the radio frequency front-end module. Among them, the band-pass filter is the core device responsible for signal transceiver, allowing only signals of specific frequencies to pass through. To meet the requirements of communication systems and protocols for signal-to-noise ratio, high requirements are imposed on the performance of filtering devices such as passband flatness, in-band insertion loss, band-edge steepness, rectangularity, and out-of-band rejection, and these requirements are increasing day by day. Elastic wave filters play a crucial role in the field of radio frequency front-end devices due to their advantages such as small size and simple process.

[0003] For the current elastic wave device structure, since the length of the interdigital electrodes in the transverse direction is limited, there is an "electrode-air" interface at the end of the interdigital electrodes. The change in the sound speed at this boundary is from low to high. Therefore, the main elastic wave mode together with the transverse high-order spurious modes are confined within the interdigital electrodes and superimposed and enhanced in the propagation direction of the elastic wave. As a result, multiple mode resonance peaks will exist simultaneously in this device structure, distributed at different frequency points between the main mode resonance frequency and the anti-resonance frequency, causing ripples in the passband of the filtering device, leading to problems such as increased insertion loss and deteriorated steepness of the passband edge, which will seriously affect signal transceiver and device temperature stability.

[0004] To address this spurious response problem, most of the current solutions are to perform deformation design on the electrodes, such as tapered electrodes, that is, there are staggered breaks at different positions in the middle of each interdigital electrode to adjust the transverse resonance cavity length of each interdigital electrode, breaking the elastic wave energy superposition of the high-order modes to eliminate the high-order spurious resonance peaks. However, at the same time, the main elastic wave energy of the fundamental mode will also be greatly affected, resulting in a decrease in the quality factor of the device and problems such as an increase in the passband loss of the filter. Additionally, there are methods of adjusting the duty cycle of the interdigital electrodes, thickening the electrodes at the end of the interdigital electrodes, or stacking dielectrics at the end of the interdigital electrodes to adjust the velocity profile curve and elastic wave energy integration, thereby suppressing the high-order spurious resonance peaks. However, this requires high line width accuracy and overlay alignment accuracy in the manufacturing process, increasing the process difficulty and cost.

[0005] Therefore, it is necessary to provide an elastic wave device. Summary of the Invention

[0006] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide an elastic wave device to solve the performance problems faced by elastic wave devices in the prior art.

[0007] To achieve the above object and other related objects, the present invention provides an elastic wave device, which includes:

[0008] Support substrate;

[0009] A piezoelectric layer located on the support substrate, and the slow shear wave velocity of the support substrate is greater than the sound velocity of the target mode propagating in the piezoelectric layer;

[0010] A functional regulation layer located on the piezoelectric layer, the slow shear wave velocity of the functional regulation layer is greater than the sound velocity of the target mode, and interdigital grooves are provided in the functional regulation layer;

[0011] Interdigital electrodes located in the interdigital grooves.

[0012] Optionally, the interdigital grooves include one or a combination of through grooves penetrating the functional regulation layer, open grooves with bottoms located in the functional regulation layer, and embedded grooves located inside the functional regulation layer.

[0013] Optionally, the thickness of the interdigital electrodes includes one or a combination of being greater than, equal to, or less than the depth of the interdigital grooves.

[0014] Optionally, there is a gap between the side walls of the interdigital electrodes and the functional regulation layer.

[0015] Optionally, the functional regulation layer further includes window grooves provided in the area near the finger ends of the interdigital electrodes.

[0016] Optionally, the morphology of the window grooves includes one or a combination of circular, elliptical, fan-shaped, and polygonal shapes; a filling material layer is further provided in the window grooves, and the slow shear wave velocity of the filling material layer is less than the slow shear wave velocity of the functional regulation layer.

[0017] The present invention further provides an elastic wave device, and the elastic wave device includes:

[0018] Support substrate;

[0019] A piezoelectric layer located on the support substrate, and the slow shear wave velocity of the support substrate is greater than the sound velocity of the target mode propagating in the piezoelectric layer;

[0020] A functional regulation layer located on the piezoelectric layer, the slow shear wave velocity of the functional regulation layer is greater than the sound velocity of the target mode, and window grooves are provided in the functional regulation layer;

[0021] Interdigital electrodes located on the functional regulation layer, and the window grooves are provided in the area near the finger ends of the interdigital electrodes.

[0022] Optionally, the topography of the window trench includes one or a combination of a circle, an ellipse, a sector, and a polygon; a filling material layer is further provided in the window trench, and the slow shear wave velocity of the filling material layer is less than that of the functional regulation layer.

[0023] Optionally, when the duty cycle of the interdigital electrode is denoted as M, the thickness of the functional regulation layer is denoted as T, the width W of the window trench in the acoustic wave propagation direction is M≤W, the length L of the window trench in the transverse cavity direction is 0.5M<L≤2M, and the thickness H of the window trench is 0.5T≤H≤T.

[0024] Optionally, the support substrate includes a silicon carbide substrate, a diamond substrate, a diamond-like carbon substrate, a gallium nitride substrate, a boron carbide substrate, a boron nitride substrate, or an aluminum nitride substrate; or the support substrate includes a substrate at the lower part and a functional layer at the upper part, the substrate includes a silicon substrate, a quartz substrate, or a sapphire substrate, and the functional layer includes one or a combination of a polysilicon layer, a silicon oxide layer, a fluorine-containing silicon oxide layer, a silicon oxynitride layer, an aluminum nitride layer, a tantalum pentoxide layer, and a tellurium dioxide layer.

[0025] Optionally, the crystal type of the functional regulation layer includes single crystal or polycrystal; the functional regulation layer includes one or a combination of an aluminum nitride layer, a silicon carbide layer, a diamond layer, a diamond-like carbon layer, a silicon nitride layer, a sapphire layer, a magnesium oxide layer, an aluminum oxide layer, a silicon layer, a gallium nitride layer, a boron carbide layer, and a boron nitride layer.

[0026] Optionally, the thermal conductivity of the functional regulation layer is greater than that of the piezoelectric layer.

[0027] As described above, the elastic wave device of the present invention is provided with a functional regulation layer having interdigital trenches and / or window trenches, and the acoustic velocity of elastic waves in the piezoelectric layer region contacted by the functional regulation layer is increased through the functional regulation layer, so as to regulate the velocity profile curve of the target acoustic wave in the acoustic wave propagation direction; the patterned functional regulation layer having interdigital trenches and / or window trenches can provide a turning interface for the velocity profile curve in the acoustic wave propagation direction, so that the energy integration of the high-order stray elastic waves is significantly reduced or even zero, thereby weakening and suppressing the excitation of the high-order elastic waves.

[0028] Through the arrangement of the patterned functional regulation layer, the present invention can effectively adjust the velocity profile curve and energy integration of elastic waves, thereby weakening or suppressing the excitation of the transverse stray mode, which is beneficial for the resonator and / or filter to achieve a flat passband, reduce the insertion loss, improve the rectangularity and the steepness of the sidebands, simplify the interdigital electrode structure. At the same time, the functional regulation layer with high acoustic velocity and high Young's modulus helps to improve the temperature stability of the device structure. In addition, the functional regulation layer also has the advantages of protecting the metal interdigital electrode and surface passivation, which can improve the heat dissipation performance and service life of the elastic wave device, thereby increasing the power capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Among them, (a)-(e) show cross-sectional views of the elastic wave device with interdigital grooves proposed by the present invention. Figure 1 Among them, (f) shows a cross-sectional view of an existing elastic wave resonator.

[0030] Figure 2 Show a cross-sectional view of the elastic wave device with interdigital grooves proposed by the present invention.

[0031] Figure 3 Show the comparison diagrams of the velocity profile curves in the second direction of the structure of Comparative Example 1 and Figure 1 (a)-(d) and Figure 2 (a) of the five structures.

[0032] Figure 4 Show the top view, cross-sectional view and velocity profile curve of the structure of Comparative Example 1.

[0033] Figure 5 Show the top view, cross-sectional view and velocity profile curve of the structure of Example 2.

[0034] Figure 6 Show the simulated admittance and conductance curves of the horizontally polarized shear elastic wave in the structure of Comparative Example 1.

[0035] Figure 7 Show the simulated admittance and conductance curves of the horizontally polarized shear elastic wave in the structure of Example 1.

[0036] Figure 8 Show the simulated admittance and conductance curves of the horizontally polarized shear elastic wave in the structure of Example 2.

[0037] Figure 9 Show the simulated admittance and conductance curves of the horizontally polarized shear elastic wave in the structure of Example 3.

[0038] Figure 10 Show the simulated admittance and conductance curves of the horizontally polarized shear elastic wave in the structure of Example 4.

[0039] Figure 11 Show the simulated admittance and conductance curves of the horizontally polarized shear elastic wave in the structure of Example 5.

[0040] Figure 12 (a)-(e) show cross-sectional views of the elastic wave device with interdigital grooves proposed by the present invention. Figure 12 (f) shows a cross-sectional view of an existing elastic wave resonator.

[0041] Figure 13 Show a cross-sectional view of the elastic wave device with interdigital grooves proposed by the present invention.

[0042] Figure 14 Show the simulation admittance and conductance curves of the horizontal shear elastic wave in the structure of Comparative Example 2.

[0043] Figure 15 Show the simulation admittance and conductance curves of the horizontal shear elastic wave in the structure of Example 6.

[0044] Figure 16 Show the simulation admittance and conductance curves of the horizontal shear elastic wave in the structure of Example 7.

[0045] Figure 17 (a)-(e) Show the cross-sectional views of the elastic wave device with interdigital grooves proposed by the present invention. Figure 17 (f) Show the cross-sectional view of the existing elastic wave resonator.

[0046] Figure 18 Show the cross-sectional view of the elastic wave device with interdigital grooves proposed by the present invention.

[0047] Figure 19 Show the simulation admittance and conductance curves of the horizontal shear elastic wave in the structure of Comparative Example 3.

[0048] Figure 20 Show the simulation admittance and conductance curves of the horizontal shear elastic wave in the structure of Example 8.

[0049] Figure 21 Show the simulation admittance and conductance curves of the horizontal shear elastic wave in the structure of Example 9.

[0050] Figure 22 Show the top view, cross-sectional view and velocity profile curves of the structure of Example 10.

[0051] Figure 23 Show the top view of the structure of Example 11.

[0052] Figure 24 Show the top view of the structure of Example 12.

[0053] Figure 25 Show the top view, cross-sectional view and velocity profile curves of the structure of Example 13.

[0054] Figure 26 Show other top views of the structure of Example 13.

[0055] Figure 27 Show the simulation admittance and conductance curves of the horizontal shear elastic wave in the structures of Examples 14 - 16.

[0056] Figure 28 Show the top view, cross-sectional view and velocity profile curves of the structure of Example 17.

[0057] Figure 29 Shown is a top view of the structure of Example 18.

[0058] Figure 30 Shown is a top view of the structure of Example 19.

[0059] Figure 31 Shown is a top view of the structure of Example 20.

[0060] Figure 32 Shown is a top view of the structure of Example 21.

[0061] Figure 33 Shown is a top view of the structure of Example 22.

[0062] Figure 34 Shown is a top view of the structure of Example 23.

[0063] Figure 35 Shown are a top view and a cross-sectional view of the structure of Example 24.

[0064] Figure 36 Shown is another top view of the elastic wave resonator with window grooves proposed by the present invention.

[0065] Explanation of Reference Numerals

[0066] 100 Support Substrate

[0067] 110 Substrate

[0068] 201 First Functional Layer

[0069] 202 Second Functional Layer

[0070] 210 Window Groove

[0071] 220 Gap

[0072] 300 Piezoelectric Layer

[0073] 400 Functional Regulation Layer

[0074] 500 Interdigital Electrode

[0075] 600 Reflection Grating Electrode

[0076] 700 Filling Material Layer Detailed Implementation Manner

[0077] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0078] When detailing the embodiments of the present invention, for ease of description, the cross-sectional views showing the device structure will be enlarged locally in a non-general proportion, and the schematic diagrams are only examples and should not limit the scope of protection of the present invention herein. In addition, in actual production, three-dimensional spatial dimensions including length, width, and depth should be included.

[0079] For convenience of description, spatial relationship terms such as "under", "below", "lower than", "beneath", "above", "on", etc. may be used herein to describe the relationship between one element or feature shown in the drawings and other elements or features. It will be understood that these spatial relationship terms are intended to include other directions of the device in use or operation, in addition to the directions depicted in the drawings. Embodiments may include those in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact. Additionally, when a layer is referred to as being "between" two layers, it may be the only layer between the two layers, or there may be one or more intervening layers.

[0080] It should be noted that the illustrations provided in this embodiment only schematically illustrate the basic concept of the present invention. Therefore, only the components related to the present invention are shown in the illustrations, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, quantities, and proportions of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0081] For ease of description, in this embodiment, the direction of sound wave propagation is defined as the first direction, the direction of the lateral cavity is defined as the second direction, and the thickness direction is defined as the third direction. Among them, the elastic wave wavelength determined by the period of the interdigital electrodes is λ, and the interdigital electrodes are divided along the second direction into: a first bus region, a first gap region, a central aperture region, a second gap region, and a second bus region, as Figure 4 shown in (b) below.

[0082] As Figure 17Among (a) - (e), this embodiment provides an elastic wave device. The elastic wave device includes a support substrate 100, a piezoelectric layer 300, a functional regulation layer 400, and interdigital electrodes 500. Among them, the piezoelectric layer 300 is located on the support substrate 100, and the slow shear wave velocity of the support substrate 100 is greater than the sound velocity of the target mode propagating in the piezoelectric layer 300; the functional regulation layer 400 is located on the piezoelectric layer 300, the slow shear wave velocity of the functional regulation layer 400 is greater than the sound velocity of the target mode, and interdigital grooves (not shown) are provided in the functional regulation layer 400; the interdigital electrodes 500 are located in the interdigital grooves.

[0083] Specifically, the material of the functional regulation layer 400 has the characteristic of high sound velocity. Its slow shear wave velocity is higher than the target sound velocity of the piezoelectric layer 300. The energy of the elastic wave is mainly concentrated in the piezoelectric layer 300. The functional regulation layer 400 can effectively increase the propagation sound velocity of the elastic wave in the piezoelectric layer 300; the functional regulation layer 400 has the characteristic of increasing the elastic wave sound velocity in the area of the piezoelectric layer 300 it contacts, while the elastic wave sound velocity in the area of the piezoelectric layer 300 not contacted by the functional regulation layer 400 is not increased. And the patterning of the functional regulation layer 400 in the thickness or surface direction can provide a turning interface of the velocity profile curve in the second direction, so as to adjust the boundary conditions of the elastic wave and the higher-order elastic wave at the interface and the energy integration in the second direction, thereby effectively suppressing the excitation of the higher-order elastic wave.

[0084] As an example, the interdigital grooves include one or a combination of a through groove penetrating the functional regulation layer 400, an open groove with a bottom located in the functional regulation layer 400, and an embedded groove located inside the functional regulation layer 400.

[0085] Specifically, as shown in Figure 17 (a), (b), (c), (e) in the figure, it shows the case where the interdigital groove is a through groove penetrating the functional regulation layer 400. As shown in Figure 18 (a), (b), (c) in the figure, it shows the case where the interdigital groove is an open groove with a bottom located in the functional regulation layer 400. Figure 17 In (d) in the figure and Figure 18 (d) in the figure shows the case where the interdigital groove is an embedded groove located inside the functional regulation layer 400. According to needs, the elastic wave device can also be set to include a combination of the through groove, the open groove, and the embedded groove.

[0086] As an example, the thickness of the interdigital electrodes 500 includes one or a combination of being greater than, equal to, or less than the depth of the interdigital grooves, such as Figure 17 and Figure 18Illustrates a diagram where the thickness of the interdigital electrode 500 is greater than, equal to, or less than the depth of the interdigital groove.

[0087] As an example, there is a gap 220 between the sidewall of the interdigital electrode 500 and the functional regulation layer 400.

[0088] Specifically, as Figure 17 shown in (e) of, there is a gap 220 between the sidewall of the interdigital electrode 500 and the functional regulation layer 400. Among them, in the first direction, preferably the width of the gap 220 is not greater than 0.1λ.

[0089] As an example, the support substrate 100 is a material with the characteristics of high Young's modulus, low density, and high sound velocity. Its slow shear wave sound velocity is higher than the target sound wave sound velocity of the piezoelectric layer 300. Its materials include but are not limited to silicon carbide substrates, diamond substrates, diamond-like substrates, gallium nitride substrates, boron carbide substrates, boron nitride substrates, or aluminum nitride substrates of various cut types. Regarding the type and thickness of the support substrate 100, flexible selection can be made and no excessive restrictions are imposed here.

[0090] In another embodiment, the support substrate 100 can also be composed of a base 110 located at the lower part and a functional layer located at the upper part. The base 110 can include a silicon substrate, a quartz substrate, or a sapphire substrate, and the functional layer can include one or a combination of a polysilicon layer, a silicon oxide layer, a fluorine-containing silicon oxide layer, a silicon oxynitride layer, an aluminum nitride layer, a tantalum pentoxide layer, and a tellurium dioxide layer.

[0091] Specifically, by combining the base 110 with ordinary high sound velocity and the functional layer, an effective reflection of the target sound wave energy is formed. This combination can replace the support substrate 100 with high sound velocity. The functional layer can also simultaneously have functions such as adsorbing free carriers inside and at the interface of the material in contact with it, and / or reflecting and constraining elastic wave energy, and / or compensating for temperature stability. Among them, the functional layer can be a single-layer film formed by a single-layer material, such as Figure 1 , or it can also be a composite film structure composed of multiple-layer materials, such as Figure 12 . The functional layer can be composed of a combination of a first functional layer 201 and a second functional layer 202. Among them, preferably the total thickness of the functional layer is less than 2.5μm.

[0092] Regarding the type and thickness of the base 110, flexible selection can be made and no excessive restrictions are imposed here. Regarding the type, number of layers, and thickness of the functional layer, flexible selection can be made and no excessive restrictions are imposed here.

[0093] In this embodiment, in a half-period unit with a width of λ / 2 including an interdigital coverage area and an interval area without interdigital coverage, according to the distribution position of the functional control layer 400, the device structure included in the half-period unit can be divided into the following four combinations in the third direction (the structures are stacked in order from top to bottom): combination A: functional control layer I-piezoelectric layer-support substrate and interdigital electrode-piezoelectric layer-support substrate, wherein the thickness of the functional control layer I can be greater than, less than or equal to the thickness of the interdigital electrode, see Figure 17 (a) to (c); combination B: functional regulation layer I-piezoelectric layer-support substrate and functional regulation layer II-interdigitated electrode-piezoelectric layer-support substrate, wherein the surface of functional regulation layer II is flush with the surface of functional regulation layer I, see Figure 17 (d); C combination: functional control layer I-piezoelectric layer-support substrate and interdigital electrodes-functional control layer III-piezoelectric layer-support substrate, wherein the surface of the functional control layer I can be higher than, lower than or flush with the surface of the interdigital electrodes, see Figure 18 (a) to (c); D combination: functional regulation layer I-piezoelectric layer-support substrate and functional regulation layer II-interdigitated electrode-functional regulation layer III-piezoelectric layer-support substrate, wherein the surface of functional regulation layer II is flush with the surface of functional regulation layer I, see Figure 18 Middle (d).

[0094] The functional regulation layer 400 can be regarded as a thickness patterned functional regulation layer with interdigitated grooves after being patterned along a third direction, wherein the functional regulation layer 400 has the characteristics of high sound velocity, and its slow shear wave sound velocity is higher than the target sound wave sound velocity of the piezoelectric layer 300; the functional regulation layer 400 has the function of increasing the sound velocity of the target sound wave in the piezoelectric layer 300 it contacts; the patterned functional regulation layer 400 can maximize the increase in the sound velocity of the target sound wave in the piezoelectric layer 300 corresponding to the central aperture area, effectively reduce the sound velocity difference between the target sound wave in the piezoelectric layer 300 corresponding to the central aperture area and the gap area, and this sound velocity is higher than the sound velocity of the target sound wave in the piezoelectric layer 300 corresponding to the busbar area.

[0095] As an example, the duty cycle ranges of the functional regulation layer I, the functional regulation layer II, and the functional regulation layer III are all 0.2λ to 0.8λ, such as 0.2λ, 0.4λ, 0.6λ, 0.8λ, etc., and can be specifically set according to needs.

[0096] As an example, the thickness range of the function regulation layer I can be 0.015λ to λ, such as 0.015λ, 0.03λ, 0.1λ, 0.5λ, λ, etc. The thickness range of the function regulation layer II can be 0 to 0.3λ, such as 0λ, 0.1λ, 0.2λ, 0.3λ, etc. The thickness range of the function regulation layer III can be 0 to 0.3λ, such as 0λ, 0.1λ, 0.2λ, 0.3λ, etc., and can be specifically set according to needs.

[0097] As an example, along the second direction, the ranges of the first void region and the second void region can be 0 to 2 times the duty cycle.

[0098] As an example, the crystal type of the function regulation layer 400 includes single crystal or polycrystal; the function regulation layer 400 includes, but is not limited to, one or a combination of aluminum nitride layer, silicon carbide layer, diamond layer, diamond-like carbon layer, silicon nitride layer, sapphire layer, magnesium oxide layer, aluminum oxide layer, silicon layer, gallium nitride layer, boron carbide layer, and boron nitride layer.

[0099] As an example, the thermal conductivity of the function regulation layer 400 is greater than that of the piezoelectric layer 300.

[0100] Specifically, when the thermal conductivity of the material of the function regulation layer 400 is higher than that of the piezoelectric material, it helps to promote the heat dissipation of the device, and at the same time, as a protective layer for the interdigital electrode 500 structure, the preparation steps of the passivation layer of the elastic wave device can be omitted or simplified, and the life and power capacity of the elastic wave device can be improved.

[0101] As an example, the types of materials of the piezoelectric layer 300 include, but are not limited to, lithium tantalate, lithium niobate, quartz, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lead zirconate titanate, lead magnesium niobate titanate, gallium nitride, gallium oxide, gallium arsenide and other materials of various cut types; the thickness range of the piezoelectric layer 300 is 0.03λ to λ, such as 0.03λ, 0.1λ, 0.5λ, λ, etc.

[0102] As an example, the interdigital electrode 500 can be a single-layer metal or an interleaved stack of multiple metal materials; the types of materials include, but are not limited to, any one or more alloys composed of copper, silver, gold, aluminum, platinum, nickel, molybdenum, tungsten, chromium, and titanium; when it is a single-layer electrode, the electrode thickness range can be 0.02λ to 0.12λ, such as 0.02λ, 0.08λ, 0.1λ, 0.12λ, etc.

[0103] As an example, in the second direction, reflection grating electrodes 600 can also be included on both sides of the interdigital electrode 500 to reflect acoustic wave energy through the reflection grating electrodes 600, thereby reducing the leakage of acoustic waves in the horizontal propagation direction, such as Figure 4(a), wherein, to ensure sufficient excitation of elastic waves and effective energy confinement, the interdigital electrode 500 and the reflective grating electrode 600 preferably use the same metal material, stacking structure, and electrode thickness, but they can also be set separately.

[0104] As an example, the target mode may include, but is not limited to, horizontal shear waves, vertical shear waves, longitudinal leaky waves, higher-order horizontal shear waves, higher-order vertical shear waves, higher-order longitudinal waves, etc.; the elastic wave device may include an elastic wave resonator and / or an elastic wave filter.

[0105] As an example, refer to Figure 22 and Figure 25 , the functional regulation layer 400 may further include window trenches 210 disposed in the region near the finger tips of the interdigital electrode 500, wherein the morphology of the window trenches 210 may include one or a combination of circular, elliptical, fan-shaped, and polygonal shapes; the window trenches 210 may further have a filler material layer 700.

[0106] Regarding the setting and effect of the window trenches 210 and the filler material layer 700, no introduction will be made here for the time being. For details, refer to the introduction of the elastic wave device having the window trenches 210 below.

[0107] Refer to Figure 22 , this embodiment further provides an elastic wave device, which includes a support substrate 100, a piezoelectric layer 300, a functional regulation layer 400, and an interdigital electrode 500. Among them, the piezoelectric layer 300 is located on the support substrate 100, and the slow shear wave velocity of the support substrate 100 is greater than the sound velocity of the target mode propagating in the piezoelectric layer 300; the functional regulation layer 400 is located on the piezoelectric layer 300, the slow shear wave velocity of the functional regulation layer 400 is greater than the sound velocity of the target mode, and the window trenches 210 are provided in the functional regulation layer 400; the interdigital electrode 500 is located on the functional regulation layer 400, and the window trenches 210 are disposed in the region near the finger tips of the interdigital electrode 500.

[0108] Regarding the specific materials, structures of the support substrate 100, the piezoelectric layer 300, the functional regulation layer 400, and the interdigital electrode 500, as well as the setting of functional layers, reflective grating electrodes 600, etc., please refer to the above introduction of the elastic wave device, which will not be elaborated here. Only the setting of the window trenches 210 will be described in detail below.

[0109] For ease of description, as Figure 22, in this embodiment, the distribution of the functional regulation layer 400 can be at least divided into a first bus bar region, a first gap region, a first window region, a first boundary, a central aperture region, a second boundary, a second window region, a second gap region, and a second bus bar region along the second direction. Among them, the first window region is located close to the first bus bar region, and the second window region is located close to the second bus bar region.

[0110] Specifically, the functional regulation layer 400 can be regarded as a surface-patterned functional regulation layer with window grooves after patterning the surface formed along the first direction and the second direction. Within a half-period unit with a λ / 2 width including an interdigital coverage area and an interval area without interdigital coverage, according to the distribution position of the functional regulation layer 400, except for the window region where the window groove is located, the device structures included in the half-period unit can be regarded as (in the order of stacking from top to bottom), interdigital electrode-functional regulation layer-piezoelectric layer-supporting substrate and functional regulation layer-piezoelectric layer-supporting substrate in the third direction. The rules for such functional regulation layer patterning are: First: The functional regulation layer 400 has the characteristic of high sound velocity, and its slow shear wave sound velocity is higher than the target sound velocity of the piezoelectric layer 300; Second: The functional regulation layer 400 has the effect of increasing the target sound velocity within the piezoelectric layer 300 it contacts; Third: The target sound velocity within the piezoelectric layer 300 corresponding directly below the window region is less than or equal to the target sound velocity of the piezoelectric layer 300 corresponding below the central aperture region.

[0111] Among them, the position settings of the first window region and the second window region determine the positioning of the turning boundary of the velocity profile curve in the second direction; when described by one interdigital finger and its adjacent gap region within a half period, the window region can be opened only near the end position of the interdigital electrode 500, or only near the end position region of the gap between two interdigital fingers 220 (the region not covered by the interdigital electrode 500), or through holes can be opened, that is, windows are opened at both the end position of the interdigital finger and the end region of the gap between two interdigital fingers 220.

[0112] The first window region and the second window region can also be weighted, that is, a "window" is split into two or more window regions, and derivative regions such as a third window region, a fourth window region, a third boundary, a fourth boundary, a third gap region, a fourth gap region, etc. appear in the second direction, such as Figures 32 to 35 .

[0113] Furthermore, the surface patterning of the functional regulation layer 400 can also be to form morphologies such as an arc-shaped boundary and an angularly inclined boundary near the end of the interdigital electrode 500.

[0114] As an example, such as Figure 25, a filling material layer 700 may also be provided in the window trench 210.

[0115] Specifically, the window trench 210 may be filled with a third material other than the materials corresponding to the piezoelectric layer 300 and the functional regulation layer 400, so that its surface is flush with the void region, facilitating the enhancement of the flatness of the interdigital structure. At the same time, other beneficial effects can also be achieved. For example, a material with a frequency-temperature stability opposite to that of the piezoelectric layer 300 can be filled to enhance the frequency-temperature stability of the support substrate 100 and the device; a material with a high thermal conductivity higher than that of the piezoelectric layer 300 can be filled to enhance the heat dissipation efficiency, etc. Specifically, it can be filled as needed, but the slow shear wave velocity of the filled filling material layer 700 should be less than the slow shear wave velocity of the functional regulation layer 400.

[0116] Among them, the filling material layer 700 may include, but is not limited to, materials such as polysilicon, silicon oxide, silicon oxynitride, silicon carbonitride, and fluorine-containing silicon oxide, and the thickness range of the filling material layer 700 may be 0 to 1 times the thickness of the piezoelectric layer 300.

[0117] As an example, the morphology of the window trench 210 may include one or a combination of a circle, an ellipse, a sector, and a polygon, such as a circle, an ellipse, a triangle, a square, a rectangle, a trapezoid, and a polygon with more than four sides.

[0118] Among them, when the duty cycle of the interdigital electrode 500 is denoted as M and the thickness of the functional regulation layer 400 is denoted as T, the width W of the window trench 210 in the first direction may be M ≤ W, the length L of the window trench 210 in the second direction may be 0.5M < L ≤ 2M, and the thickness D of the window trench 210 in the third direction may be 0.5T ≤ D ≤ T. The remaining thickness of the functional regulation layer 400 in the third direction may be uniform or non-uniform, such as gradually changing.

[0119] Furthermore, the window trench 210 may be a Figure 24 , Figure 31 shown connected through-hole.

[0120] The following further introduces and illustrates the elastic wave device in the present application with specific embodiments.

[0121] Embodiment 1

[0122] The following takes Figure 1 the structures of the elastic wave resonators shown in (a), (b), and (d) therein as Examples 1-3, and the structure after removing the patterned functional regulation layer with interdigital grooves in this structure Figure 1As shown in (f) as Comparative Example 1, the admittance and conductance curves of the resonator passband in four cases are compared to illustrate the lateral clutter suppression effect of the elastic wave resonator in this embodiment.

[0123] Comparative Example 1: Figure 1 (As shown in (f), sapphire is used as the supporting substrate; silicon dioxide (SiO2) is used as the energy reflection layer and temperature compensation layer; 42°YX lithium tantalate (LiTaO3) is used as the piezoelectric thin film; metal aluminum (Al) interdigital fingers are used as the surface electrode assembly; and the SH-SAW mode is excited. At this time, the elastic wave resonator does not have a functional regulation layer.

[0124] Examples 1-3: Figure 1 (As shown in (a), (b), and (d), sapphire is used as the supporting substrate; SiO2 is used as the energy reflection layer and temperature compensation layer; 42°YX LiTaO3 is used as the piezoelectric thin film; aluminum nitride (AlN) thin film is used as the functional regulation layer; metal Al interdigital fingers are used as the surface electrode assembly; and the horizontal shear elastic wave SH-SAW mode is excited. At this time, the elastic wave resonator has a patterned AlN layer with interdigital grooves in the thickness direction. The patterning operation on the AlN layer is as follows: interdigital grooves are opened at specific positions of the AlN layer that uniformly covers the surface of the piezoelectric layer. These interdigital grooves are through grooves, that is, the depth is equal to the thickness of the AlN layer, and then the interdigital electrodes are filled into the interdigital grooves. The thickness of the filled interdigital electrodes can be greater than, less than, or equal to the thickness of the AlN layer. Figure 1 The device structures corresponding to (a) and (b) in are used as Example 1 and Example 2 respectively. In addition, Figure 1 the structure shown in (d) in is used as Example 3. This structure is based on Figure 1 the structure in (c) in. After filling the interdigital electrodes, a layer of AlN layer is covered on the upper surface of the device and planarized. Among them, the Al interdigital electrodes are in direct contact with the piezoelectric layer.

[0125] In Figure 1 the structure shown, the thickness of LiTaO3 is 360 nm, the thickness of SiO2 is 400 nm, the thickness of the AlN layer is 100 nm, the interdigital period is 1.2 μm, the duty cycle is 0.5, and the duty cycle of the AlN groove is also 0.5.

[0126] In Example 1, the schematic structural diagram is shown in Figure 1 (a) in. At this time, the thickness of the Al electrode is greater than the thickness of the AlN layer. The depth of the AlN groove formed in the thickness direction is 100 nm, and the thickness of the Al interdigital electrode is 120 nm. Therefore, the electrode is exposed on the surface. In Example 2, the schematic structural diagram is shown in Figure 1In (b), at this time, the thickness of the Al electrode is less than that of the AlN layer. The depth of the AlN groove is 100 nm, and the thickness of the Al interdigital electrode is 80 nm. Therefore, the interdigital electrode is completely embedded in the AlN layer; in Example 3, the structural schematic diagram is as shown in Figure 1 (d). The depth of the AlN groove is 100 nm, and the thickness of the Al interdigital electrode is 80 nm. Therefore, the interdigital electrode is buried in the preset groove surrounded by AlN, and the surface of the device is planarized. Additionally, it can also be a structure as shown in Figure 1 in (c)-(e).

[0127] Figure 3 Shows the comparison schematic diagram of the velocity profile curves in the second direction of the structure of Comparative Example 1 and the five structures shown in Figure 1 and 2 respectively. Among them, the black line in (a) in Figure 3 corresponds to Comparative Example 1, and the dashed line corresponds to Example 1. Obviously, the functional regulation layer material increases the acoustic velocity inside the piezoelectric layer material it contacts. Among them, the acoustic velocities in the first void region and the second void region are significantly enhanced, about 188.7 m / s; the central aperture region is the region covered by the functional regulation layer in an interleaved manner, and the acoustic velocity enhancement is the largest, about 285.8 m / s. More importantly, not only is the acoustic velocity in the central aperture region the largest in terms of enhancement, exceeding the acoustic velocity in the first busbar region, but it also effectively reduces the acoustic velocity difference ΔV between this acoustic velocity and the target acoustic velocity in the corresponding piezoelectric layer below the void region, that is, from 251.3 m / s to 128.5 m / s. Thus, it effectively changes the profile of the velocity curve, as well as the vibration state and energy integral of the transverse high-order mode, thereby effectively weakening the reflection of high-order elastic waves and effectively suppressing the excitation and vibration of multiple high-order transverse clutter.

[0128] Similarly, Figure 3 the dashed lines in (b), (c), (d), and (e) in Figure 1 respectively give the comparison schematic diagrams of the velocity profile curves of the structures shown in (b), (c), (d) in Figure 2 and (a) in

[0129] Since the velocity profile curve and boundary conditions in the second direction affect the energy integration of elastic waves inside the interdigital aperture, they thus affect the excitation and elimination of higher-order modes. Therefore, starting from the analysis of the velocity profile curve, the characteristics and advantages of the new device structure provided by this application are introduced.

[0130] Figure 4 Figure (a) shows a complete top view of the interdigital structure on the surface of the elastic wave device. The active region, that is, the central interdigital region, is analyzed below. As Figure 4 shown in Figure (b), in the elastic wave device shown in Comparative Example 2, according to the different material stack structures, the device can be divided into the following regions along the second direction: the first bus region, the first gap region, the central aperture region, the second gap region, and the second bus region. The boundary between the central aperture region and the first gap region is called the first boundary, and the boundary between the central aperture region and the second gap region is called the second boundary. Due to the mass loading effect of the metal electrode, the sound velocities of the elastic waves propagating in the corresponding piezoelectric layers below these different regions along the second direction are also different. Taking a pair of interdigital electrodes as an example, it can be divided into three different velocity regions: ① the periodic region containing 1 interdigital electrode; ② the periodic region containing 2 interdigital electrodes; ③ the periodic region containing 1.5 interdigital electrodes. In addition, for the device structure of Comparative Example 2, the greater the metal coverage rate, the lower the corresponding elastic wave sound velocity. Therefore, the velocity relationship among the three regions is: ①>③>②. Therefore, the velocity profile curve in the second direction is marked by the left black solid line.

[0131] Since the length of the interdigital aperture in the second direction is limited, when the elastic waves propagate to the first boundary and the second boundary respectively in the second direction, due to the fact that both the first gap region and the second gap region are high-velocity regions, the elastic waves encounter a velocity barrier and will undergo strong reflection at the first boundary and the second boundary. As Figure 4 shown in Figure (d) and Figure 4 Figure (e), the displacement field distributions of the elastic waves of the fundamental mode and the higher-order mode in the second direction are different, thus resulting in different energy integrations of the two types of modal elastic waves. For the main mode of the elastic wave of the fundamental mode, as Figure 4 shown in Figure (d), piezoelectric energy conversion effectively occurs in the central aperture region, and the first boundary and the second boundary provide good energy confinement for the elastic waves, thereby suppressing their leakage to the bus region. The slanted shaded part is the effective energy integration; but for the higher-order mode, such as the second-order mode, its displacement field is as Figure 4As shown in (e), when strong reflections occur at the first boundary and the second boundary of the elastic wave, the horizontal shaded area is where the energies cancel each other out, and the diagonal shaded area is the effective energy integration. When the diagonal shaded area of the second-order transverse elastic wave is not zero, its effective excitation will result in a very strong spurious response being introduced within the passband. The same applies to other higher-order elastic waves. Note that the fundamental mode defined and utilized here refers to the fundamental mode in the second direction, rather than the acoustic wave mode being restricted to the fundamental mode. The fundamental and higher-order modes in the first and third directions can all serve as effective main modes. For example, the first-order and second-order horizontal shear waves can both serve as main modes.

[0132] Figure 5 (a) and (b) in the figure show the surface and cross-sectional schematic diagrams of the structure of Example 2. The interdigital electrode thickness of the functional regulation layer in Example 2 is greater than that of the functional regulation layer. Thanks to the high Young's modulus and low density characteristics of the functional regulation layer, the functional regulation layer increases the sound velocity of the target acoustic wave in the piezoelectric layer it contacts, and the velocity profile curve in the second direction becomes Figure 5 the shape marked by the black solid line on the left side of (a) in the figure. The sound velocity in the central aperture region increases to be closer to the sound velocity in the void region and is significantly higher than the sound velocity in the busbar region. Then, at this time, the reflection coefficients of the transverse fundamental mode (main mode) and the transverse higher-order mode (spurious mode) at the first boundary and the second boundary in the second direction change, and the corresponding energy integration also changes relatively. As Figure 5 shown in (c) in the figure, the vibration of the main mode rapidly decays at the boundary, thus restricting the acoustic wave energy more uniformly and effectively in the central aperture region (the horizontal shaded area); as Figure 5 shown in (d) in the figure, the reflection coefficients of the spurious mode at the first boundary and the second boundary are closer to 1, and most of the energy integrations within the central aperture region cancel each other out (the horizontal shaded area indicates the mutual cancellation of energy, and the elastic wave energy in the window region rapidly decays), so it is effectively suppressed. Other higher-order modes also have the same characteristics, and the energy integration in the second direction in the central aperture region is approximately 0 and thus no longer excited. Therefore, the patterned functional regulation layer at the interdigital end can effectively suppress the excitation of higher-order spurious modes, reduce the introduced parasitic spurious response, and reduce problems such as insertion loss.

[0133] Figure 6 Shows the simulation admittance and conductance curve diagrams of the SH-SAW in the structure of Comparative Example 1. When no measures for suppressing transverse clutter are taken, the frequency response of the resonator shows multiple-order spurious modes within the passband between the resonant frequency and the anti-resonant frequency, which will seriously affect the passband response of the filter when designing and building the filter, including in-band flatness, insertion loss, band-edge steepness, and temperature-variation stability, etc.

[0134] Figure 7 Shows the simulation admittance and conductance curve diagrams of the SH-SAW in the structure of Example 1.Figure 8 shows the simulated admittance and conductance curves of the SH-SAW in the structure of Example 2. Figure 9 shows the simulated admittance and conductance curves of the SH-SAW in the structure of Example 3. By Figures 7 - 9 comparison with Figure 6 it can be found that, compared with Comparative Example 1, in Examples 1-3, whether the thickness of the interdigital electrode metal is less than or greater than the depth of the AlN groove, the sharp resonance peaks in the admittance curve show the effective excitation and resonance of the main mode; the number of transverse higher-order spurious modes is significantly reduced, and the resonance intensity is also significantly weakened, indicating that this structure can effectively suppress the transverse spurious modes. At the same time, the corresponding conductance curve does not show local or overall elevation, indicating that this structure can suppress or weaken the transverse spurious modes without sacrificing the quality factor of the main mode, and thus does not increase the device loss. Then, exciting the elastic wave mode in this structure shows an effective spurious mode suppression effect.

[0135] Examples 4-5: Figure 2 As shown in (a) and (b) in, sapphire is used as the supporting substrate; SiO2 is used as the energy reflection layer and temperature compensation layer; 42°YX LiTaO3 is used as the piezoelectric thin film; AlN is used as the functional regulation layer; metal Al interdigital fingers are used as the surface electrode assembly; to excite the horizontal shear elastic wave SH-SAW mode. At this time, the elastic wave resonator has an AlN thin film with a thickness-directional pattern including interdigital grooves. The patterning operation on AlN is: opening a window at a specific position of the AlN layer that uniformly covers the surface of the piezoelectric layer. This window is a non-through groove, and its depth is less than the thickness of AlN. There is still a certain thickness of AlN layer on the surface of the piezoelectric layer at the bottom of the window, and then the interdigital electrode is filled into the window. The electrode thickness can be greater than, less than or equal to the thickness of AlN. Figure 2 The device structures corresponding to (a) and (b) in are used as Example 4 and Example 5 respectively.

[0136] In Figure 2 the structure shown, when the thickness of LiTaO3 is 360 nm, the thickness of SiO2 is 400 nm, the thickness of the AlN layer is 100 nm, the interdigital period is 1.2 μm, the duty cycle is 0.5, and the duty cycle of the AlN groove is also 0.5.

[0137] In Example 4, the schematic diagram of the structure is shown in Figure 2 (a) in, there is a 10-nm AlN layer at the bottom of the interdigital electrode, that is, the depth of the AlN groove is 90 nm, and the thickness of the Al interdigital electrode is 80 nm. Therefore, the interdigital electrode is completely embedded in the AlN groove; in Example 5, the schematic diagram of the structure is shown in Figure 2In (b), there is a 20 nm thick AlN layer at the bottom of the interdigital electrode, that is, the AlN groove depth is 80 nm, and the thickness of the Al interdigital electrode is 80 nm, which is flush with the AlN groove depth. Therefore, the upper surfaces of the interdigital electrode and the AlN layer form a common flat surface. Additionally, it can also be Figure 2 the structures shown in (c) and (d).

[0138] Figure 10 shows the simulated admittance and conductance curves of the SH-SAW in the structure of Example 4. Figure 11 shows the simulated admittance and conductance curves of the SH-SAW in the structure of Example 5. By Figure 10 and Figure 11 and Figure 6 comparing with, it can be found that, compared with Comparative Example 1, in Example 4 and Example 5, whether the thickness of the metal is less than or equal to the AlN groove depth, the main mode can be effectively excited and resonated; the number of high-order spurious modes is significantly reduced, and their resonance intensity is greatly weakened, indicating that this structure can effectively suppress the lateral spurious modes. The corresponding conductance curve does not show local or overall elevation, indicating that this structure will not increase the loss and will not cause a decrease in the quality factor of the device. Therefore, this structure can also effectively suppress the excitation of lateral spurious modes.

[0139] As can be seen from the above examples, by using this substrate structure, the number of lateral spurious mode excitations in the passband can be effectively reduced, thereby reducing the in-band jitter of the filter and improving the in-band flatness, insertion loss, band-edge steepness, reliability and other performance of the device. Moreover, for the device with this structure, there is no need for special electrode design, sacrificing the interdigital line width, sacrificing the electromechanical coupling coefficient, or damaging the integrity of the piezoelectric film, which greatly simplifies the manufacturing process and reduces the manufacturing difficulty.

[0140] In addition, in order to further suppress the excitation of lateral spurious modes, the device structure can be further optimized, such as designing the total thickness of the AlN layer, the duty cycle of the AlN groove, the depth of the AlN groove, the shape and angle of the AlN groove edge, the thickness of the AlN layer at the bottom of the electrode, the total thickness of the interdigital electrode, the embedding depth of the electrode, the electrode duty cycle, etc. By adopting the device structures shown in Figure 1 and Figure 2 from the perspective of the substrate structure, the excitation of lateral spurious modes can be suppressed or weakened, which simplifies the design and manufacturing scheme of the elastic wave device.

[0141] Particularly, when the selected high acoustic velocity material has high thermal conductivity, the direct contact between the piezoelectric layer and this function regulation layer can also provide an efficient heat dissipation channel and enhance the heat dissipation capacity of the device.

[0142] Example 2

[0143] Next, taking Figure 12The structures of the elastic wave resonators shown in (a) and (b) are used as Example 6-7. After removing the patterned function control layer with interdigital grooves from this structure Figure 12 As Comparative Example 2 shown in (f), the admittance and conductance curves of the resonator passband in three cases are compared to illustrate the lateral clutter suppression effect of the elastic wave resonator described in this embodiment.

[0144] Comparative Example 2: Figure 12 As shown in (f), a polysilicon layer and high-resistance silicon are used as the support substrate; a SiO2 composite layer is used as the energy reflection layer and temperature compensation layer; 42°YX LiTaO3 is used as the piezoelectric thin film; metal Al interdigital fingers are used as the surface electrode assembly; the SH-SAW mode is excited. At this time, the elastic wave resonator does not have a function control layer.

[0145] The thickness of LiTaO3 is 360 nm, the thickness of SiO2 is 400 nm, the thickness of polysilicon is 1.0 μm, the interdigital period is 1.2 μm, and the duty cycle is 0.5.

[0146] Example 6-7: Figure 12 As shown in (a) and (b), a polysilicon layer and high-resistance silicon are used as the support substrate; a SiO2 composite layer is used as the energy reflection layer and temperature compensation layer; 42°YX LiTaO3 is used as the piezoelectric thin film; AlN is used as the function control layer; metal Al interdigital fingers are used as the surface electrode assembly; the horizontal shear elastic wave SH-SAW mode is excited. At this time, the elastic wave resonator has a thickness-direction patterned AlN layer, that is, an AlN layer with interdigital grooves. The patterning operation performed on the AlN layer is: opening interdigital grooves at specific positions of the AlN layer that uniformly covers the surface of the piezoelectric layer. These interdigital grooves are through grooves, that is, the depth is equal to the thickness of the AlN layer. Then, the interdigital electrodes are filled into the interdigital grooves. The thickness of the filled interdigital electrodes can be greater than, less than, or equal to the thickness of the AlN layer. Figure 12 The corresponding device structures in (a) and (b) are used as Example 6 and Example 7 respectively. The thickness of the AlN layer is 100 nm, the thickness of LiTaO3 is 360 nm, the thickness of SiO2 is 400 nm, the thickness of polysilicon is 1.0 μm, the interdigital period is 1.2 μm, the duty cycle is 0.5, and the duty cycle of the AlN groove is also 0.5. The depth of the AlN groove is 100 nm. The thickness of the Al electrode in the structure of Example 6 is 120 nm, and the thickness of the Al electrode in the structure of Example 7 is 80 nm.

[0147] Figure 14The simulated admittance and conductance curves of the SH-SAW in the structure of Comparative Example 2 are shown. When no lateral clutter suppression measures are taken, the frequency response of the resonator shows that there are multiple-order spurious modes in the passband between the resonant frequency and the anti-resonant frequency, which will seriously affect the passband response of the filter when designing and building the filter, including in-band flatness, insertion loss, band-edge steepness, and temperature stability.

[0148] Figure 15 The simulated admittance and conductance curves of the SH-SAW in the structure of Example 6 are shown. Figure 16 The simulated admittance and conductance curves of the SH-SAW in the structure of Example 7 are shown. By Figures 15 - 16 comparing with Figure 14 , it can be found that, compared with Comparative Example 2, in Examples 6-7, whether the thickness of the interdigital electrode metal is less than or greater than the depth of the AlN groove, the sharp resonant peaks in the admittance curve show the effective excitation and resonance of the main mode; the number of lateral high-order spurious modes is significantly reduced, and the resonance intensity is also significantly weakened, indicating that this structure can effectively suppress the lateral spurious modes. At the same time, the corresponding conductance curve does not show local or overall elevation, indicating that this structure can suppress or weaken the lateral spurious modes without sacrificing the quality factor of the main mode, so it will not increase the device loss. Then, exciting the elastic wave mode in this structure shows an effective spurious mode suppression effect.

[0149] Same as Embodiment 1, this structure can also be the structure as shown in Figure 13 . At this time, the elastic wave resonator has an AlN layer patterned in the thickness direction, that is, an AlN layer with interdigital grooves. The patterning operation performed on the AlN layer is: opening interdigital grooves at specific positions of the AlN layer that uniformly covers the surface of the piezoelectric layer. These interdigital grooves are non-through grooves, that is, the depth is less than the thickness of the AlN, and there is still a certain thickness of the AlN layer at the bottom of the interdigital grooves on the surface of the piezoelectric layer, and then the interdigital electrodes are filled into the interdigital grooves. The electrode thickness can be greater than ( Figure 13 in (c)), less than ( Figure 13 (a)) or equal to ( Figure 13 (b)) the depth of the groove. As shown in Figure 13 (d), a layer of AlN can also be covered on the surface and flattened, and the metal is buried in the AlN layer.

[0150] Embodiment 3

[0151] Next, taking the structures of the elastic wave resonators shown in (a) and (b) in Figure 17 as Examples 8-9, the structure after removing the functional regulation layer with interdigital grooves patterned in this structure is Figure 17As shown in (f) as Comparative Example 3, the admittance and conductance curves of the resonator passband in three cases are compared to illustrate the lateral clutter suppression effect of the elastic wave resonator described in this embodiment.

[0152] Comparative Example 3: Figure 17 As shown in (f), silicon carbide (SiC) is used as the supporting substrate; 42°YX LiTaO3 is used as the piezoelectric thin film; metal Al interdigital fingers are used as the surface electrode assembly; and the SH-SAW mode is excited. At this time, the elastic wave resonator does not have a functional regulation layer. The thickness of LiTaO3 is 400 nm, the interdigital period is 1.0 μm, and the duty cycle is 0.5.

[0153] Examples 8-9: Figure 17 As shown in (a) and (b) therein, SiC is used as the supporting substrate; 42°YX LiTaO3 is used as the piezoelectric thin film; 42°YX LiTaO3 is used as the piezoelectric thin film; an AlN thin film is used as the functional regulation layer; metal Al interdigital fingers are used as the surface electrode assembly; and the horizontal shear elastic wave SH-SAW mode is excited. At this time, the elastic wave resonator has a thickness-direction patterned AlN layer, that is, an AlN layer with interdigital grooves. The patterning operation performed on the AlN layer is as follows: an AlN layer is opened at a specific position of the AlN layer that uniformly covers the surface of the piezoelectric layer. This AlN layer is a through groove, that is, the depth is equal to the thickness of the AlN layer, and then the interdigital electrodes are filled into the AlN layer. The thickness of the filled interdigital electrodes can be greater than, less than, or equal to the thickness of the AlN. Figure 17 The device structures corresponding to (a) and (b) therein are used as Example 8 and Example 9 respectively. The thickness of the AlN layer is 100 nm, the thickness of LiTaO3 is 400 nm, the interdigital period is 1.0 μm, the duty cycle is 0.5, the duty cycle of the AlN groove is also 0.5, and the depth of the AlN groove is 100 nm. The thickness of the Al electrode in the structure of Example 8 is 120 nm, and the thickness of the Al electrode in the structure of Example 9 is 80 nm.

[0154] Figure 19 Shows the simulated admittance and conductance curve graphs of SH-SAW in the structure of Comparative Example 3. When no lateral clutter suppression measures are taken, the frequency response of the resonator shows multiple spurious modes in the passband between the resonant frequency and the anti-resonant frequency, which will seriously affect the passband response of the filter when designing and building the filter, including in-band flatness, insertion loss, band-edge steepness, and temperature stability.

[0155] Figure 20 Shows the simulated admittance and conductance curve graphs of SH-SAW in the structure of Example 8. Figure 21 Shows the simulated admittance and conductance curve graphs of SH-SAW in the structure of Example 9. By Figures 20 - 21 and Figure 19Through comparison, it can be found that, compared with Comparative Example 3, in Examples 8-9, regardless of whether the thickness of the interdigital electrode metal is less than or greater than the AlN groove depth, the sharp resonance peaks in the admittance curve show the effective excitation and resonance of the main mode; the number of transverse higher-order spurious modes is significantly reduced, and the resonance intensity is also significantly weakened, indicating that this structure can effectively suppress the transverse spurious modes. At the same time, the corresponding conductance curve does not show local or overall elevation, indicating that this structure can suppress or weaken the transverse spurious modes without sacrificing the quality factor of the main mode, and thus does not increase the device loss. Then, exciting the elastic wave mode in this structure shows an effective spurious mode suppression effect.

[0156] Similar to Embodiment 1 and Embodiment 2, this structure can also be as Figure 18 shown in the figure. At this time, the elastic wave resonator has an AlN thin film patterned in the thickness direction, that is, an AlN layer with interdigital grooves. The patterning operation on the AlN layer is as follows: opening interdigital grooves at specific positions of the AlN layer that uniformly covers the surface of the piezoelectric layer. These interdigital grooves are non-through grooves, that is, the depth is less than the thickness of the AlN layer, and there is still a certain thickness of the AlN layer at the bottom of the interdigital grooves on the surface of the piezoelectric layer. Then, the interdigital electrodes are filled into the interdigital grooves. The electrode thickness can be greater than ( Figure 18 (c)), less than ( Figure 18 (a)) or equal to ( Figure 18 (b)) the depth of the groove. As Figure 18 (d) shows, a layer of AlN can also be covered on the surface and planarized, and the metal is buried in the AlN.

[0157] Embodiment 4

[0158] In Embodiment 1, through Figure 4 the velocity profile curve of the target acoustic wave in the second direction, as well as the excitation and energy integration states of the transverse fundamental mode and spurious modes, were introduced in the traditional elastic wave structure design.

[0159] As Figure 22 shown in the cross-sectional views of (d) and (e) in the figure, for the elastic wave device structure described in Example 10, a functional regulation layer is introduced between the piezoelectric layer and the interdigital electrodes. Due to the high Young's modulus and low density characteristics of the functional regulation layer, as long as this material layer exists between the piezoelectric layer and the interdigital electrodes, it can effectively increase the sound velocity of the elastic wave in the piezoelectric layer. When the functional regulation layer is patterned, for example, locally removing the functional regulation layer corresponding to the position below the end of each interdigital finger to form window grooves, as Figure 22As shown in the top view of (a), the removed areas at the ends of the first boundary and the second boundary are defined as the "first window" and the "second window" respectively. The sound velocity of the elastic wave in the piezoelectric layer corresponding to the first window and the second window areas is relatively not increased. Compared with the increase in the sound velocity of other areas, the relative sound velocity magnitude in the window area changes from the original i to ii or iii or vi, which depends on the design parameters of the preset groove. That is, the sound velocity of the piezoelectric layer corresponding to the window area may still be greater than the central aperture area covered by the electrode, may be exactly equal to the central aperture area, or may be less than the central aperture area. Assuming a change from i to iii, the velocity profile curve is adjusted to be as shown by the left black solid line in (a) of Figure 22 In the new device structure, referring to the velocity profile curve, when the elastic wave propagates to the first boundary and the second boundary, the velocity boundary faced by the elastic wave becomes the "high sound velocity - low sound velocity" corresponding to the "central aperture area - window area", and the displacement field distribution and energy integration are as shown in (b)-(c) of Figure 22 Since when crossing the relatively narrow first and second window areas, the elastic wave will face the velocity barrier of "low sound velocity - high sound velocity" with a larger sound velocity difference between the third boundary and the fourth boundary and the window area, even if the sound velocity in the central aperture area is higher than that in the window area, the energy of the fundamental mode elastic wave rapidly decays in the window area, thereby more evenly and effectively confining the acoustic wave energy in the central aperture area (the horizontal shaded area), forming an effective energy confinement, significantly reducing the scattering loss, enabling the excitation of the fundamental main mode to be more efficient, and being beneficial to improving the quality factor of the device.

[0160] For the higher-order spurious modes, the high velocity barriers at the first boundary and the second boundary are replaced by the window area, that is, the boundary conditions for strong reflection change. At this time, the reflection coefficients of the higher-order modes at the first boundary and the second boundary are approximately -1, as shown in (c) of Figure 22 In the same way, taking the second-order clutter as an example, since the field distribution of the second-order mode in the second direction is different from that of the elastic wave of the fundamental mode, the change in the boundary conditions makes the energy integration of the higher-order mode in the second direction approximately 0 (the horizontal shaded area indicates the mutual cancellation of energy, and the elastic wave energy in the window area rapidly decays), so it can be effectively suppressed. Other higher-order modes also have the same characteristics, and the energy integration in the second direction in the central aperture area is approximately 0 and thus no longer excited. Therefore, the patterned functional control layer at the ends of the interdigital fingers can effectively suppress the excitation of higher-order spurious modes, reduce the introduced parasitic spurious response, and reduce problems such as insertion loss.

[0161] Since the elastic wave mainly propagates inside the piezoelectric layer, the window area is opened inside the functional control layer without patterning the piezoelectric layer, so the integrity of the piezoelectric thin film can be guaranteed, which is beneficial to the propagation of the elastic wave, reduces losses such as scattering, and maintains the quality factor.

[0162] In addition, in the region where the window is opened, the local functional regulation layer is removed to form a window groove. Then, a third substance other than the piezoelectric layer and the functional regulation layer can be filled in the window groove, such as Figure 25 shown, making its surface flush with the void region so that the interdigital electrode assembly has a uniform height. At the same time, other third effects can also be provided: for example, filling a material with a low Young's modulus (the Young's modulus of the third substance needs to be less than that of the functional regulation layer) helps to regulate and reduce the elastic wave sound velocity in this window region, assisting the functional regulation layer to flexibly adjust the velocity profile curve; filling a material with high temperature stability helps to improve the temperature stability of the substrate structure and the device, and improve the frequency temperature stability; filling a material with high thermal conductivity helps to enhance the heat dissipation efficiency, etc. Therefore, it can be filled as needed. In addition, the shapes of the opened window and the filled third substance can also be various types as Figure 26 shown.

[0163] Figure 23 Schematic diagram of the device substrate structure (top view of the surface) of the elastic wave resonator in Example 11; Figure 24 Schematic diagram of the device substrate structure (top view of the surface) of the elastic wave resonator in Example 12; Figure 25 Schematic diagram of the device substrate structure (top view of the surface and cross-sectional view) of the elastic wave resonator in Example 13 and the velocity profile curves corresponding to the fundamental mode and the high-order mode (taking the second order as an example); Figure 26 Schematic diagram of other implementable example structures that can be evolved from the top view of the surface of the elastic wave resonator shown in Example 13.

[0164] Example 5

[0165] For the case where the surface-patterned functional regulation layer, that is, the patterned functional regulation layer with window grooves, is used to suppress the lateral spurious modes, three structures of Example 14, 15, and 16 are set up, and their main-mode resonances are simulated.

[0166] The surface patterning structure of the AlN layer in Example 14 is as Figure 24Shown as follows: sapphire is used as the supporting substrate; SiO2 is used as the energy reflection layer and temperature compensation layer; 42°YX LiTaO3 is used as the piezoelectric thin film; the surface-patterned AlN thin film is used as the functional regulation layer, that is, the AlN layer with window trenches; metal Al interdigital fingers are used as the surface electrode assembly; the horizontal shear elastic wave SH-SAW mode is excited and generated. The patterning operation on the AlN layer is as follows: window trenches are opened in the AlN layer corresponding to the surface of the piezoelectric layer at the position of the interdigital finger end region, and the depth of this window trench is equal to the thickness of the AlN layer (it can also be that the window trenches are opened in advance and then the interdigital electrodes are formed by aligning the positions). For the structure described in Example 14, the thickness of LiTaO3 is 360 nm, the thickness of the surface AlN layer is 30 nm, the thickness of SiO2 is 400 nm, the interdigital period is 1.2 μm, and the duty cycle is 0.5. Window trenches are opened, the size of the window trench in the first direction is an open hole, the height in the second direction is 0.4λ, and the depth in the third direction is 30 nm.

[0167] Schematic diagrams of the surface patterning structures of the AlN layers with window trenches in Examples 15 and 16 are as Figure 26 (b) shown: sapphire is used as the supporting substrate; SiO2 is used as the energy reflection layer and temperature compensation layer; 42°YX LiTaO3 is used as the piezoelectric thin film; the surface-patterned AlN thin film with window trenches is used as the functional regulation layer; metal Al interdigital fingers are used as the surface electrode assembly; the horizontal shear elastic wave SH-SAW mode is excited and generated. The patterning operation on the AlN layer is as follows: window trenches are opened in the AlN layer corresponding to the surface of the piezoelectric layer at the position of the interdigital finger end region, and the depth of this window trench is equal to the thickness of the AlN layer (it can also be that the window trenches are opened in advance and then the interdigital electrodes are formed by aligning the positions), and then the third substance SiO2 is filled in the window trenches.

[0168] For the structure described in Example 15, the thickness of LiTaO3 is 360 nm, the thickness of the surface AlN layer is 30 nm, the thickness of SiO2 is 400 nm, the interdigital period is 1.2 μm, and the duty cycle is 0.5. Window trenches are opened, the size of the window trench in the first direction is an open hole, the height in the second direction is 0.4λ, and the depth in the third direction is 30 nm, and the thickness of the third substance SiO2 filled in the window trench is 30 nm. For the structure described in Example 16, the thickness of LiTaO3 is 360 nm, the thickness of the surface AlN layer is 30 nm, the thickness of SiO2 is 400 nm, the interdigital period is 1.2 μm, and the duty cycle is 0.4. Window trenches are opened, the size of the window trench in the first direction is an open hole, the height in the second direction is 0.4λ, and the depth in the third direction is 30 nm, and the thickness of the third substance SiO2 filled in the window trench is 30 nm.

[0169] Figure 27(a), (b), and (c) of [the figure] respectively show the admittance and conductance curves of the resonator transverse model simulations of the structures of Example 14, Example 15, and Example 16. When only window trenches of the functional regulation layer are opened in the finger tip region, that is, the simulation results corresponding to Example 14 ( Figure 27 (a)), the transverse spurious modes in the passband have been significantly suppressed. At this time, it does not sacrifice the line width of the interdigital electrodes, and the main mode energy can be effectively constrained in the central aperture region, and high quality factor and low insertion loss can be maintained; when window trenches of the functional regulation layer are opened in the finger tip region and a third substance with a smaller Young's modulus is filled in the window trenches, that is, the simulation results corresponding to Example 15 ( Figure 27 (b)), the transverse spurious modes in the passband are basically completely suppressed. At this time, the duty cycle of the interdigital electrodes is still 0.5, ensuring the stability and simplicity of the line width of the interdigital electrodes and the fabrication process; similarly, the main mode energy can be effectively constrained in the central aperture region, maintaining high quality factor and low insertion loss. When window trenches of the functional regulation layer are opened in the finger tip region and a third substance with a smaller Young's modulus is filled in the window trenches, and then the duty cycle of the interdigital electrodes is further reduced to 0.4, that is, the simulation results corresponding to Example 16 ( Figure 27 (c)), the transverse spurious modes in the passband are basically completely suppressed. The simulation results of these three examples all prove the effective suppression and elimination of the surface patterned functional regulation layer on the transverse high-order spurious modes, which helps to improve the flatness in the passband, reduce the insertion loss, and enhance the power capacity and frequency temperature stability.

[0170] The shapes of the first window region and the second window region, as well as their dimensions in the first direction, the second direction, and the third direction, all affect the sound velocity of the elastic wave in the corresponding piezoelectric layer in this region (the degree of regulation of the elastic wave sound velocity), thereby affecting the contour of the velocity curve in the second direction. The shapes of the first window region and the second window region where the window trenches are located include but are not limited to circular, elliptical (such as Figure 30 ), triangular, square, rectangular, trapezoidal, and polygons with more than four sides. Different patterning treatments can be performed on adjacent finger tips simultaneously to regulate the velocity.

[0171] The positions of the first window region and the second window region determine the positioning of the turning boundary of the velocity profile curve in the second direction. When taking a half cycle composed of one finger and its adjacent region as the analysis object, the window trenches can be opened only at the end position of the interdigital electrode, or only at the end position region between two fingers, or window trenches can also be opened at both the finger tip and the adjacent region. The relative positions of the two window trenches can be connected or relatively staggered. Different patterning treatments can also be performed on adjacent finger tips simultaneously to regulate the velocity. (Such as Figure 23 , Figure 24 , Figure 29as shown)

[0172] Dimensions of the first window region and the second window region: Here, the dimensions of the window are constrained with the window groove shape being rectangular. When the duty cycle of the interdigital electrode is denoted as M and the thickness of the functional regulation layer is denoted as T, the range of the first direction W is: M ≤ W; the range of the second direction L is: 0.5M < L ≤ 2M; the range of the third direction H is: 0.5T ≤ H ≤ T for the functional regulation layer. When the first direction is for opening holes (such as Figure 24 and Figure 31 as shown), the depth in the third direction can be unevenly distributed along the first direction. Additionally, the dimensions of the void regions in the window region are also constrained. Meanwhile, when the window groove shape is rectangular, along the second direction, the ranges of the first void region and the second void region can be: 0 - 2M. Furthermore, the first window region and the second window region can also be weighted, that is, it is also possible to be in the shape of multiple window grooves. As Figure 22 (a) shown, the first window region and the second window region can be respectively divided into 2 or more window areas, thus giving rise to third, fourth, fifth, sixth, and so on window and void regions (such as Figures 32 - 34 as shown). The relative positions of different window grooves can be aligned or staggered / interleaved. For the case of multiple window grooves, in the direction pointing from the midpoint of the central aperture to the upper and lower sides, the arrangement sequence of the boundary, window, and void is: first boundary - window - then void region.

[0173] In addition, the functional regulation layer can be implemented synchronously with the interdigital grooves and the window grooves, such as Figure 28 、 Figure 35 as shown.

[0174] Embodiment 6

[0175] In addition, the surface patterning of the functional regulation layer with window grooves can also be processed in the manner as Figure 36 shown, where the edges of the four profiles can all be arc-shaped.

[0176] As described above, for the elastic wave device structure of this embodiment, introducing a functional regulation layer between the piezoelectric layer and the interdigital electrode can effectively increase the sound velocity of elastic waves in the piezoelectric layer. For the window region where the functional regulation layer is removed, the sound velocity in the corresponding piezoelectric layer remains unchanged. When the profile of the surface patterning slot is inclined, relative to other regions where the sound velocity is increased, the boundary of the interdigital tip actually superimposes an inclined velocity profile boundary, thereby breaking the propagation boundary condition of the higher-order mode, and thus can achieve weakening the excitation of transverse higher-order clutter. The edges of the profile can all be arc-shaped. Not limited to straight lines, not limited to the inclination angle.

[0177] In summary, for the elastic wave device of the present invention, a functional regulation layer with interdigital grooves and / or window grooves is provided. By means of the functional regulation layer, the sound velocity of elastic waves in the piezoelectric layer region in contact therewith is increased, thereby regulating the velocity profile curve of target sound waves in the sound wave propagation direction. The patterned functional regulation layer with interdigital grooves and / or window grooves can provide a turning interface for the velocity profile curve in the sound wave propagation direction, so that the energy integration of higher-order spurious elastic waves is significantly reduced or even zero, thereby weakening and suppressing the excitation of higher-order elastic waves.

[0178] By providing the patterned functional regulation layer, the present invention can effectively adjust the velocity profile curve and energy integration of elastic waves, thereby weakening or suppressing the excitation of transverse spurious modes, which is beneficial for the resonator and / or filter to achieve a flat passband, reduce the insertion loss, improve the rectangularity and the steepness of the sidebands, simplify the interdigital electrode structure. At the same time, the functional regulation layer with a high sound velocity and a high Young's modulus helps to improve the temperature stability of the device structure. In addition, the functional regulation layer also has the advantages of protecting the metal interdigital electrodes and surface passivation, which can improve the heat dissipation performance and the service life of the elastic wave device, thereby increasing the power capacity.

[0179] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. An elastic wave device, characterized in that, The elastic wave device includes: A support substrate; A piezoelectric layer located on the support substrate, and the slow shear wave velocity of the support substrate is greater than the sound velocity of the target mode propagating in the piezoelectric layer; A function regulation layer located on the piezoelectric layer, the slow shear wave velocity of the function regulation layer is greater than the sound velocity of the target mode, and the function regulation layer is provided with interdigital grooves for patterning the function regulation layer. The interdigital grooves include open grooves with bottoms located in the function regulation layer, and the sound velocity is adjusted by the patterned function regulation layer; Interdigital electrodes located in the interdigital grooves.

2. The elastic wave device according to claim 1, characterized in that: The interdigital grooves further include one or a combination of through grooves penetrating the function regulation layer and embedded grooves located inside the function regulation layer.

3. The elastic wave device according to claim 1, characterized in that: The thickness of the interdigital electrodes includes one or a combination of being greater than, equal to, or less than the depth of the interdigital grooves.

4. The elastic wave device according to claim 1, characterized in that: There is a gap between the side walls of the interdigital electrodes and the function regulation layer.

5. The elastic wave device according to any one of claims 1 to 4, characterized in that: The function regulation layer further includes window grooves provided in the area near the finger ends of the interdigital electrodes.

6. The elastic wave device according to claim 5, wherein: The morphology of the window grooves includes one or a combination of circular, elliptical, fan-shaped, and polygonal shapes; the window grooves further have a filling material layer, and the slow shear wave velocity of the filling material layer is less than the slow shear wave velocity of the function regulation layer.

7. An elastic wave device, characterized in that, The elastic wave device includes: A support substrate; A piezoelectric layer located on the support substrate, and the slow shear wave velocity of the support substrate is greater than the sound velocity of the target mode propagating in the piezoelectric layer; A function regulation layer located on the piezoelectric layer, the slow shear wave velocity of the function regulation layer is greater than the sound velocity of the target mode, and the function regulation layer is provided with window grooves for patterning the function regulation layer, and the sound velocity is adjusted by the patterned function regulation layer; Interdigital electrodes located on the function regulation layer, and the window grooves are provided in the area near the finger ends of the interdigital electrodes.

8. The elastic wave device according to claim 7, wherein: The morphology of the window grooves includes one or a combination of circular, elliptical, fan-shaped, and polygonal shapes; the window grooves further have a filling material layer, and the slow shear wave velocity of the filling material layer is less than the slow shear wave velocity of the function regulation layer.

9. The elastic wave device according to claim 7, wherein: When the duty cycle of the interdigital electrodes is denoted as M, the thickness of the function regulation layer is denoted as T, the width W of the window grooves in the direction of acoustic wave propagation is M ≤ W, the length L of the window grooves in the direction of the transverse cavity is 0.5M < L ≤ 2M, and the thickness H of the window grooves is 0.5T ≤ H ≤ T.

10. The elastic wave device according to claim 1 or 7, characterized in that: The support substrate includes a silicon carbide substrate, a diamond substrate, a diamond-like carbon substrate, a gallium nitride substrate, a boron carbide substrate, a boron nitride substrate, or an aluminum nitride substrate; or the support substrate includes a base at the lower part and a functional layer at the upper part, and the base includes a silicon substrate, a quartz substrate, or a sapphire substrate, and the functional layer includes one or a combination of a polysilicon layer, a silicon oxide layer, a fluorine-containing silicon oxide layer, a silicon oxynitride layer, an aluminum nitride layer, a tantalum pentoxide layer, and a tellurium dioxide layer.

11. The elastic wave device according to claim 1 or 7, characterized in that: The crystal types of the functional regulation layer include single crystals or polycrystals; the functional regulation layer includes one or a combination of aluminum nitride layer, silicon carbide layer, diamond layer, diamond-like carbon layer, silicon nitride layer, sapphire layer, magnesium oxide layer, aluminum oxide layer, silicon layer, gallium nitride layer, boron carbide layer, and boron nitride layer.

12. The elastic wave device according to claim 1 or 7, characterized in that: The thermal conductivity of the functional regulation layer is greater than that of the piezoelectric layer.

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