Acoustic wave device

Abstract

The utility model provides an acoustic wave device which is designed based on a relation principle of a slowness curve and a stray mode, and through research, when the slowness curve is convex, the stray mode appears at a frequency higher than a resonant frequency, and when the slowness curve is concave, the stray mode appears at a frequency band lower than the resonant frequency, and the stray mode appears at a frequency band lower than the resonant frequency. When the slowness curve is adjusted in the direction perpendicular to the transverse axis, the stray mode is correspondingly suppressed; based on the principle, the relationship between the distance between the first surface and the second surface and the slowness curve is studied to discover that the distance between the first surface and the second surface is set to be greater than 0.05 lambda and less than or equal to 1.19 lambda, and the slowness curve of the acoustic wave device can be adjusted in the direction perpendicular to the transverse axis, so that the stray mode in the acoustic wave device is inhibited, and the acoustic wave device is improved. The negative influence of the stray mode on the performance inside and outside the passband of the acoustic wave device is reduced, so that the performance of the acoustic wave device is improved.

Description

TECHNICAL FIELD

[0001] The present specification relates to the technical field of semiconductor technology, in particular, to the technical field of acoustic wave devices under semiconductor technology, and more particularly, to an acoustic wave device. BACKGROUND

[0002] Acoustic wave devices are a class of devices that utilize the characteristics of acoustic wave propagation in a medium to achieve various functions. Acoustic wave devices are widely used in communication, signal processing, and sensors.

[0003] Taking a surface acoustic wave (SAW) resonator as an example, the resonant frequency, the anti-resonant frequency, and the spurious mode, etc. determine the performance of the SAW resonator. Among them, the resonant frequency and the anti-resonant frequency are of great significance to determine the working frequency range of the device, and the spurious mode may deteriorate the characteristics of the device inside and outside the passband. Therefore, it is necessary to suppress the spurious mode of the device to improve the performance of the device. UTILITY MODEL CONTENT

[0004] The embodiments of the present specification provide an acoustic wave device to achieve the purpose of suppressing the spurious mode of the acoustic wave device and improving the performance of the acoustic wave device.

[0005] To achieve the above technical purpose, the embodiments of the present specification provide the following technical solutions:

[0006] In a first aspect, an acoustic wave device is provided, comprising:

[0007] a substrate;

[0008] a piezoelectric layer located on one side of the substrate;

[0009] an interdigital transducer located on the side of the piezoelectric layer away from the substrate, the distance between the first surface and the second surface is greater than 0.05λ and less than or equal to 1.19λ, λ represents the wavelength of the acoustic wave propagating in the acoustic wave device;

[0010] The first surface includes the surface of the interdigital transducer on the side away from the piezoelectric layer, and the second surface includes the surface of the piezoelectric layer on the side away from the interdigital transducer.

[0011] In combination with the first aspect, in some embodiments of the first aspect, the distance between the first surface and the second surface is greater than 0.05λ and less than or equal to 1.1575λ.

[0012] In combination with the first aspect, in some embodiments of the first aspect, the thickness of the interdigital transducer ranges from 0.025λ to 0.2λ.

[0013] In some embodiments of the first aspect, the thickness of the interdigital transducer ranges from 0.1λ to 0.01λ.

[0014] The distance between the first surface and the second surface is greater than or equal to 0.28λ and less than or equal to 0.2825λ.

[0015] In some embodiments of the first aspect, the thickness of the piezoelectric layer ranges from 0.05λ to 1λ.

[0016] In some embodiments of the first aspect, the piezoelectric layer comprises a recessed region.

[0017] The interdigital transducer comprises a first portion and a second portion, the second portion is disposed in the recessed region, and the first portion is disposed outside the recessed region, in a target plane, the cross-sectional shape and / or size of the first portion and the second portion are different.

[0018] The target plane comprises a plane perpendicular to the first surface and the second surface.

[0019] In some embodiments of the first aspect, in the target plane, the cross-sectional shape of the first portion and the second portion comprises a rectangle, the long side of the cross-section of the second portion is smaller than the long side of the cross-section of the first portion, and the ratio of the long side of the cross-section of the second portion to the long side of the cross-section of the first portion is greater than or equal to 20%.

[0020] In some embodiments of the first aspect, in the target plane, the cross-sectional shape of the second portion comprises one of an inverted trapezoid and a triangle.

[0021] In some embodiments of the first aspect, the acoustic wave device further comprises:

[0022] A temperature compensation layer is disposed on the side of the piezoelectric layer away from the substrate, and the temperature compensation layer covers the interdigital transducer.

[0023] In some embodiments of the first aspect, the interdigital transducer comprises a single layer of metal electrodes or multiple layers of metal electrodes arranged in a stack.

[0024] A second aspect provides a computing device comprising the acoustic wave device of any one of the above aspects.

[0025] It can be seen from the technical solution that the acoustic wave device provided by the embodiments of the present specification is designed based on the principle of the relationship between the slowness curve and the spurious mode. It is found through research that when the slowness curve is convex (convex away from the coordinate axis), the spurious mode will appear at a frequency higher than the resonance frequency, and when the slowness curve is concave (concave towards the coordinate axis), the spurious mode will appear in a frequency band lower than the resonance frequency, and when the slowness curve is adjusted in a direction perpendicular to the horizontal axis, the spurious mode will be suppressed accordingly. Based on the above principle, by studying the relationship between the distance between the first surface (the surface of the interdigital transducer away from the piezoelectric layer) and the second surface (the surface of the piezoelectric layer away from the interdigital transducer) and the slowness curve, it is found that setting the distance between the first surface and the second surface to be greater than 0.05λ (λ represents the wavelength of the acoustic wave propagating in the acoustic wave device) and less than or equal to 1.19λ can adjust the slowness curve of the acoustic wave device in a direction perpendicular to the horizontal axis, thereby suppressing the spurious mode in the acoustic wave device, reducing the negative impact of the spurious mode on the performance inside and outside the passband of the acoustic wave device, and thus improving the performance of the acoustic wave device. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present specification or the prior art, the drawings required to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present specification, and those skilled in the art can also obtain other drawings according to the provided drawings without creative labor.

[0027] Figure 1 A resonator characteristic diagram of a surface acoustic wave resonator in the related art.

[0028] Figure 2 A slowness curve diagram of a surface acoustic wave resonator in the related art.

[0029] Figure 3 A diagram of the admittance & impedance-frequency characteristic curve of a surface acoustic wave resonator in the related art.

[0030] Figure 4 A slowness curve diagram of another surface acoustic wave resonator in the related art.

[0031] Figure 5 A diagram of the admittance & impedance-frequency characteristic curve of another surface acoustic wave resonator in the related art.

[0032] Figure 6 A cross-sectional structure diagram of an acoustic wave device in the related art.

[0033] Figure 7 A cross-sectional structure diagram of another acoustic wave device in the related art.

[0034] Figure 8 This is a schematic diagram of the slowness curve of the acoustic device when the distance between the first surface and the second surface takes different values.

[0035] Figure 9 This is a schematic diagram of the structure of an acoustic device provided for one embodiment of this specification.

[0036] Figure 10 This is a top view of an interdigital transducer provided as one embodiment of this specification.

[0037] Figure 11 This is a schematic diagram of a slowness curve provided for one embodiment of this specification when the values ​​of the first surface and the second surface are different.

[0038] Figure 12 This is a schematic diagram of the simulation results of a comparative device and the present device, provided as one embodiment of this specification.

[0039] Figure 13 This is a cross-sectional structural diagram of a piezoelectric layer and an interdigital transducer provided for one embodiment of this specification.

[0040] Figure 14 This is a schematic diagram comparing the slowness curve of the acoustic device provided in the embodiments of this specification with the slowness curve of a comparative device in the related art when the values ​​of L2 / L1 are different.

[0041] Figure 15 This is a cross-sectional structural diagram of an interdigital transducer provided for one embodiment of this specification.

[0042] Figure 16 This is a cross-sectional structural schematic diagram of another interdigital transducer provided for one embodiment of this specification.

[0043] Figure 17 This is a schematic diagram of a simulation structure comparing the slowness curves of the acoustic wave device provided in the embodiments of this specification with those of a comparative device in the related art when the value of θ in the device is different.

[0044] Figure 18 This is a cross-sectional structural schematic diagram of another acoustic device provided for one embodiment of this specification.

[0045] Explanation of reference numerals in the attached figures

[0046] 10-Interdigital transducer; 11-Interdigital electrode; 111-Busbar; 112-Electrode finger; 113-False finger; 12-First part; 13-Second part; 20-Piezoelectric layer; 21-Recessed region; 30-Intermediate layer; 40-Substrate; 50-Temperature compensation layer. DETAILED DESCRIPTION

[0047] Unless otherwise defined, technical terms or scientific terms used in the embodiments of the present specification shall have the same meaning as those understood by a person of ordinary skill in the art to which the embodiments of the present specification belong. The terms "first", "second", and the like used in the embodiments of the present specification do not denote any order, quantity, or importance, but are used to avoid confusion among components.

[0048] Unless the context requires otherwise, throughout the specification, "plurality" means "at least two", "include" is interpreted to be open, inclusive meaning, i.e. "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific example" or "some examples" are intended to mean that a particular feature, structure, material or characteristic included in the embodiments or examples is included in at least one embodiment or example of the specification. The illustrative representation of the above terms does not necessarily mean the same embodiment or example.

[0049] The technical solutions in the embodiments of the present specification will be described clearly and completely in the embodiments of the present specification in combination with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present specification, not all the embodiments. Based on the embodiments in the present specification, all other embodiments obtained by a person of ordinary skill in the art without making creative efforts fall within the scope of protection of the present specification.

[0050] SUMMARY

[0051] The acoustic wave device can include a surface acoustic wave device, and the surface acoustic wave technology plays an important role in the signal separation and filtering process of mobile communication. The surface acoustic wave device can include a surface acoustic wave resonator and a surface acoustic wave filter, etc. Taking the surface acoustic wave resonator as an example, the device can include a substrate, an intermediate layer, a piezoelectric layer, and an interdigital transducer (IDT) structure, etc. The interdigital transducer can include a plurality of interdigital transducers. Compared with the traditional surface acoustic wave resonator, the surface acoustic wave resonator with the multi-layer structure has less elastic wave energy leakage to the substrate direction, and has better characteristics. Figure 1 , Figure 1 The resonator characteristics of the surface acoustic wave resonator are shown, Figure 1The horizontal axis is frequency (Frequency) in units of megahertz (MHz), and the vertical axis is admittance and conductance (Admittance & Conductance) in units of decibel (dB). The main mode of the surface acoustic wave resonator at the resonant frequency is the horizontal shear wave (Horizontal Shear Wave), and the spurious mode in the frequency range between the resonant frequency and the anti-resonant frequency is caused by the transverse mode. From Figure 1 As can be seen, there are multiple spurious modes between the resonant frequency and the anti-resonant frequency of the surface acoustic wave resonator, which deteriorate the characteristics of the surface acoustic wave resonator and the surface acoustic wave filter inside and outside the passband.

[0052] To solve this problem, by studying the relationship between the slowness curve and the transverse mode, it is found that the transverse mode of the device can be well suppressed by controlling the slowness curve of the acoustic wave device. For example, referring to Figure 2 , if the slowness curve is convex (i.e. the curve is convex away from the coordinate axis), referring to Figure 3 , the spurious mode caused by the transverse mode of the device will appear in the frequency band higher than the resonant frequency. Referring to Figure 4 , if the slowness curve is concave (i.e. the curve is concave towards the coordinate axis), referring to Figure 5 , the spurious mode caused by the transverse mode of the device will not appear in the frequency band higher than the resonant frequency, but in the frequency band lower than the resonant frequency. When the slowness curve is as perpendicular to the horizontal axis as possible, the spurious mode caused by the transverse mode in the acoustic wave device is well suppressed. In the slowness curve provided in the present specification, the horizontal coordinate Sx can be a normalized value based on the Sx value at the resonant frequency, i.e. 1 / f*λ, where f represents frequency and λ represents wavelength; the value of the vertical coordinate Sy can be ky / (2*pi*f) [1 / (um*MHz)], where ky represents the wave number in the y direction.

[0053] To achieve the adjustment of the slowness curve of the acoustic wave device to the horizontal axis direction, the inventors have found through research that by controlling the distance between the upper surface of the interdigital transducer (i.e. the surface away from the piezoelectric layer, hereinafter referred to as the first surface) and the lower surface of the piezoelectric layer (i.e. the surface away from the interdigital transducer, hereinafter referred to as the second surface) in the acoustic wave device, the purpose of controlling the shape of the slowness curve of the acoustic wave device can be well achieved, thereby achieving suppression of the spurious mode in the acoustic wave device. For example, referring to Figure 6 , Figure 6 is a cross-sectional structure diagram of the acoustic wave device in the related art. When the distance D between the first surface and the second surface is too large, the slowness curve of the acoustic wave device is shaped as shown in Figure 2 , and the spurious mode will appear in the frequency band higher than the resonant frequency; referring to Figure 7When the distance between the first surface and the second surface is too small, the slowness curve of the acoustic wave device is as shown in FIG. 1C, and the spurious mode will not appear in the frequency band higher than the resonance frequency, but will appear in the frequency band lower than the resonance frequency. Referring to FIG. 1D, it is assumed that in the acoustic wave device shown in FIG. 1D, the distance D between the first surface and the second surface is a, and in the acoustic wave device shown in FIG. 1E, the distance D between the first surface and the second surface is b (a > b). By studying the relationship between the slowness curves when the distance D between the first surface and the second surface is c, d and e (a > c > d > e > b) respectively and the slowness curves corresponding to the devices shown in FIG. 1D and FIG. 1E, it can be known that by optimizing the distance between the first surface and the second surface, the perpendicularity of the slowness curve to the horizontal axis can be improved, so as to realize the suppression of the spurious mode in the acoustic wave device and realize the purpose of optimizing the performance of the acoustic wave device. Figure 4 Figure 8 Figure 6 Figure 7 Figure 6 Figure 7

[0054] Based on the above idea, an embodiment of the present specification provides an acoustic wave device, which will be exemplarily described below in combination with the drawings.

[0055] Exemplary Device

[0056] An embodiment of the present specification provides an acoustic wave device, as shown in FIG. 1A and FIG. 1B, comprising: Figure 9 Figure 10

[0057] a substrate 40;

[0058] a piezoelectric layer 20 located on one side of the substrate 40;

[0059] an interdigital transducer 10 located on the side of the piezoelectric layer 20 away from the substrate 40, the distance D between the first surface and the second surface being greater than 0.05λ and less than or equal to 1.19λ, λ representing the wavelength of the acoustic wave propagating in the acoustic wave device;

[0060] The first surface comprises the surface of the interdigital transducer 10 away from the piezoelectric layer 20, and the second surface comprises the surface of the piezoelectric layer 20 away from the interdigital transducer 10.

[0061] The substrate 40 can also be referred to as a support substrate, and the substrate 40 can be a silicon substrate 40. The substrate 40 can provide good mechanical support and electrical insulation performance for the acoustic wave device.

[0062] ​​​​​​​​The piezoelectric layer 20 can be made of materials such as lithium niobate (LiNbO3) or lithium tantalate (LiTaO3). In some embodiments, the piezoelectric layer 20 can be made of 42°YX-LiTaO3 material. This 42°YX crystal phase lithium tantalate has the characteristics of high electromechanical coupling coefficient and good temperature stability, which is beneficial to improving the performance of acoustic wave devices.

[0063] The interdigital transducer 10 can be used to excite and detect surface acoustic waves; its top view structure can be referenced. Figure 10 , Figure 10 A schematic diagram of the structure of a partial interdigital transducer 10 is shown. The interdigital transducer 10 may include components along a first direction (e.g., Figure 10 The interdigitated electrodes 11 shown in the horizontal direction are arranged opposite each other. Each interdigitated electrode 11 includes a bus-bar 111 and electrode fingers 112 extending along a first direction. The number of electrode fingers 112 can be multiple. The interdigitated electrodes 11 may also include dummy fingers 113 (or virtual fingers). The gap G between the dummy finger 113 and another interdigitated electrode 11 is called the interdigitated transducer gap (IDT Gap).

[0064] In acoustic wave devices, the value of λ can be determined based on the operating frequency of the acoustic wave device and the propagation speed of the sound wave in the piezoelectric layer 20. For example, if the propagation speed of the sound wave in the piezoelectric layer 20 is 4000 m / s (the speed of sound waves in lithium tantalate), and the target resonant frequency of the acoustic wave device is 1 GHz, then the wavelength λ can be calculated as follows: 4000 / (1*10^3) ​​= 4 μm. Thus, during the design process, based on the operating frequency of the acoustic wave device and the propagation speed of the sound wave in the piezoelectric layer 20, λ can be obtained. This allows for designing the distance D between the first and second surfaces to be greater than 0.05λ and less than or equal to 1.19λ. This allows the slowness curve of the acoustic wave device to be adjusted in a direction perpendicular to the horizontal axis, thereby suppressing stray modes in the acoustic wave device and reducing the negative impact of stray modes on the performance inside and outside the passband of the acoustic wave device, thus improving the performance of the acoustic wave device. In some embodiments, the distance between the first surface and the second surface can be 0.06λ, 0.09λ, 0.15λ, 0.3λ, 0.5λ, 0.9λ, 1.0λ, 1.1λ, 1.15λ, and 1.19λ, etc., and this specification does not limit it.

[0065] In some implementations, reference Figure 9The acoustic wave device can further include an intermediate layer 30, which can be a silicon dioxide layer. The intermediate layer 30 can serve as a buffer layer between the piezoelectric layer 20 and the substrate 40, reducing the stress and the mismatch of the coefficient of thermal expansion between the two, thereby improving the stability and reliability of the device. In addition, the intermediate layer 30 can also serve as a protective layer to prevent the piezoelectric layer 20 from being chemically or physically damaged. In some embodiments, the propagation characteristics of the surface acoustic wave can also be adjusted by the intermediate layer 30.

[0066] In one embodiment, referring to Figure 8 By adjusting the specific values of c, d, and e, it can be found that when the distance between the first surface and the second surface is greater than 0.05λ and less than or equal to 1.1575λ, the slow curve of the acoustic wave device tends to be perpendicular to the horizontal axis, thereby optimizing the ability to suppress spurious modes in the acoustic wave device and improving the performance of the acoustic wave device.

[0067] In one embodiment, the thickness of the interdigital transducer 10 has a value in the range of 0.025λ to 0.2λ. The thickness of the interdigital transducer 10 has certain effects on the resonant frequency, electromechanical coupling coefficient, and insertion loss of the acoustic wave device. For example, an increase in the thickness of the interdigital transducer 10 increases its mass, thereby producing a greater mass loading effect on the surface of the piezoelectric substrate. This mass loading effect causes the propagation speed of the acoustic wave to decrease, thereby reducing the resonant frequency. Therefore, there is a certain relationship between the thickness of the interdigital transducer 10 and the resonant frequency. Also, for example, the thickness of the interdigital transducer 10 affects its electromechanical coupling coefficient, i.e., the conversion efficiency between electrical energy and acoustic energy. Generally speaking, a proper thickness of the interdigital transducer 10 can increase the electromechanical coupling coefficient, thereby improving the energy conversion efficiency. However, if the interdigital transducer 10 is too thick, it can cause an increase in energy scattering and loss, thereby reducing the electromechanical coupling coefficient.

[0068] By comprehensively considering the effects of the interdigital transducer 10 on various parameters of the acoustic wave device, based on theoretical analysis, simulation calculation, and experimental verification, it is found that when the thickness of the interdigital transducer has a value in the range of 0.025λ to 0.2λ, a good performance of the acoustic wave device can be obtained. In some embodiments, the thickness of the interdigital transducer can have a value of 0.025λ, 0.030λ, 0.050λ, 0.090λ, 0.1λ, 0.15λ, 0.18λ, and 0.2λ, etc., which are not limited in the present specification.

[0069] In one embodiment, in order to make the slowness curve of the acoustic wave device as perpendicular to the horizontal axis as possible to maximize the suppression of the spurious mode of the acoustic wave device, the distance between the first surface and the second surface is greater than or equal to 0.28λ and less than or equal to 0.2825λ when the thickness of the interdigital transducer 10 is in the range of 0.1λ±0.01λ.

[0070] In the present embodiment, when the distance between the first surface and the second surface is greater than or equal to 0.28λ and less than or equal to 0.2825λ, the slowness curve of the acoustic wave device can be made as perpendicular to the horizontal axis as possible to obtain better spurious mode suppression performance and thus improve the device performance. For example, in some embodiments, the thickness of the interdigital transducer can be 0.09λ, 0.095λ, 0.1λ, 0.105λ, 0.11λ, etc., and the distance between the first surface and the second surface can be 0.28λ, 0.281λ, 0.2815λ, 0.282λ, 0.2825λ, etc., which are not limited in the present specification.

[0071] Specifically, in order to further study the relationship between the distance between the first surface and the second surface and the slowness curve, in one embodiment, the above conclusion is verified by simulation of a specific acoustic wave device. Assuming that the structure of the acoustic wave device is as shown in Figure 9 , the wavelength λ is 4μm, the piezoelectric layer 20 is a 42°YX-LiTaO3 layer, the intermediate layer 30 is a silicon dioxide layer, the thickness of the interdigital transducer 10 is 0.1λ (i.e. 400nm), and the thickness of the piezoelectric layer 20 is 0.225λ (i.e. 900nm), still referring to Figure 8 , when a=1300nm, b=900nm, c=1200nm, d=1100nm and e=1000nm are designed, the slowness curve as shown in Figure 8 is obtained, and by Figure 8 , it can be found that the demarcation line between the convex change and the concave change of the slowness curve is between D=1200nm~1100nm, and the result of simulation calculation using a finer step is as shown in Figure 11 , by designing the distance D between the first surface and the second surface as f, g, h, k respectively, the slowness curve as shown in Figure 11 is obtained, where c>f>g>h>k>d, and specifically, f, g, h and k can be 1140nm, 1130nm, 1120nm and 1100nm respectively, from Figure 11As can be seen from the figure, when the distance D between the first surface and the second surface is between 1120 nm and 1130 nm (0.28λ~0.2825λ), the perpendicularity of the slowness curve to the horizontal axis is the highest, and correspondingly, when the distance D between the first surface and the second surface is within the range, the suppression effect of the spurious mode in the acoustic wave device is better, and better device performance can be obtained.

[0072] In order to compare with the acoustic wave device in the related art (for example, the acoustic wave device as shown in Figure 6 , the acoustic wave device provided by the embodiment of the present specification (hereinafter referred to as the present device) and the acoustic wave device in the related art (hereinafter referred to as the comparative device) are simulated and tested, and the simulation results as shown in Figure 12 are obtained.

[0073] The parameters of the present device are shown in Table 1 as follows:

[0074] Table 1. Related parameters of the present device

[0075]

[0076] The comparative device is the same as the present device except that the distance between the first surface and the second surface is 0.325λ (1300 nm), and through the simulation results of Figure 12 , it can be found that there is an obvious spurious mode in the comparative device, while in the present device, the spurious mode is obviously suppressed by adjusting the distance between the first surface and the second surface, and the device performance is optimized.

[0077] In an embodiment, the thickness of the piezoelectric layer 20 is in the range of 0.05λ~1λ. The thickness of the piezoelectric layer 20 has an important influence on the resonant frequency, electromechanical coupling coefficient and bandwidth of the acoustic wave device. For example, the thickness of the piezoelectric layer 20 affects the propagation speed of the acoustic wave therein. A thicker piezoelectric layer 20 can cause the acoustic wave propagation speed to decrease, thereby reducing the resonant frequency. Conversely, a thinner piezoelectric layer 20 can cause the acoustic wave propagation speed to increase, thereby increasing the resonant frequency. Also for example, the thickness of the piezoelectric layer 20 affects its electromechanical coupling coefficient, i.e. the conversion efficiency between electrical energy and acoustic energy. A proper thickness of the piezoelectric layer 20 can increase the electromechanical coupling coefficient, thereby increasing the energy conversion efficiency. However, if the piezoelectric layer 20 is too thick, it can cause increased energy scattering and loss, thereby reducing the electromechanical coupling coefficient. Considering the influence of the thickness of the piezoelectric layer 20 on the above-mentioned parameters, it is found through research that when the thickness of the piezoelectric layer 20 is in the range of 0.05λ~1λ, the device can have better performance.

[0078] In an embodiment, referring to Figure 13 , the piezoelectric layer 20 comprises a recessed area 21;

[0079] The interdigital transducer 10 comprises a first portion 12 and a second portion 13, the second portion 13 is arranged in the recessed area 21, and the first portion 12 is arranged outside the recessed area 21, in the target plane, the cross-sectional shape and / or size of the first portion 12 and the second portion 13 are different.

[0080] The target plane comprises a plane perpendicular to the first surface and the second surface.

[0081] In the embodiment, the distance between the first surface and the second surface can be adjusted by arranging the recessed area 21 in the piezoelectric layer 20 and accommodating part of the interdigital transducer 10 in the recessed area 21. The shape of the second portion 13 can match the shape of the recessed area 21, so that the shape of the interdigital transducer 10 can meet the requirements of different application scenarios, and the applicability of the device is improved.

[0082] In an optional embodiment, still referring to Figure 13 , in the target plane, the cross-sectional shape of the first portion 12 and the second portion 13 comprises a rectangle, the long side of the cross section of the second portion 13 is smaller than the long side of the cross section of the first portion 12, and the ratio of the long side of the cross section of the second portion 13 to the long side of the cross section of the first portion 12 is greater than or equal to 20%.

[0083] In the embodiment, L2 / L1≥20%, so that the suppression effect of the spurious mode in the acoustic wave device can be guaranteed, and the shape of the interdigital transducer 10 can meet the requirements of different application scenarios.

[0084] Referring to Figure 14 , Figure 14 The comparison between the slowness curves when the value of L2 / L1 in the acoustic wave device provided by the embodiments of the present application and the slowness curves of the comparative device in the related art is shown, from Figure 14 It can be seen that when L2 / L1 takes values of 100%, 80%, 60%, 40% and 20% respectively, the slowness curve can still be considered to be perpendicular to the horizontal axis, and compared with the comparative device, it still has a good spurious mode suppression effect, which is beneficial to improve the performance of the acoustic wave device.

[0085] In an optional embodiment, referring to Figure 15 and Figure 16 , in the target plane, the cross-sectional shape of the second portion 13 comprises one of an inverted trapezoid and a triangle.

[0086] In Figure 15 , the cross-sectional shape of the second portion 13 comprises an inverted trapezoid, and in Figure 16 , the cross-sectional shape of the second portion 13 comprises a triangle. By adjusting the shape of the second portion 13, the shape of the interdigital transducer 10 can meet the requirements of different application scenarios.Figure 15 and Figure 16 Comparative simulation of the slowness curves of the acoustic wave device provided in the embodiments of the present disclosure and the comparative device at different θ values can obtain the slowness curves as shown in FIG. 17. It can be found from FIG. 17 that the slowness curves corresponding to the devices with different θ values (θ = 0°, 10°, 30°, 50° and 70°) are substantially perpendicular to the horizontal axis in the acoustic wave device provided in the embodiments of the present disclosure. Compared with the comparative device, the acoustic wave device provided in the embodiments of the present disclosure has a better suppression effect on the spurious mode, which is beneficial to improve the device performance. Figure 17

[0087] In one embodiment, in order to improve the temperature coefficient of frequency (TCF) of the acoustic wave device, the acoustic wave device further comprises: Figure 18 a temperature compensation layer 50, the temperature compensation layer 50 is located on the side of the piezoelectric layer 20 away from the substrate 40, and the temperature compensation layer 50 covers the interdigital transducer 10.

[0088] In the embodiments, the thermal expansion coefficient and the temperature coefficient of acoustic velocity of the temperature compensation layer 50 can be different from those of the piezoelectric layer 20. By designing the thermal expansion coefficient and the temperature coefficient of acoustic velocity of the temperature compensation layer 50, the thermal expansion and the acoustic velocity change of the temperature compensation layer 50 can be made to offset each other, thereby improving the temperature coefficient of frequency of the device.

[0089] In one embodiment, the interdigital transducer 10 can include a single-layer metal electrode or a plurality of metal electrodes arranged in a stack. The single-layer metal electrode can refer to that the interdigital transducer 10 is composed of one layer of metal electrode, which can be an aluminum electrode. The interdigital transducer 10 with a single-layer metal electrode has a simple manufacturing process, and the overall electrode quality can be relatively light, which has a small mass loading effect on the surface of the piezoelectric layer 20, and is beneficial to maintain a high resonant frequency and a high quality factor.

[0090] In the plurality of metal electrodes arranged in a stack, each layer of metal electrode can be different. For example, in one embodiment, the interdigital transducer 10 can include aluminum metal electrodes and copper metal electrodes arranged in a stack, and in another embodiment, the interdigital transducer 10 can include aluminum metal electrodes, copper metal electrodes and titanium metal electrodes arranged in a stack. The interdigital transducer 10 with such a structure has relatively small conductivity and resistance loss, which is beneficial to reduce the insertion loss and improve the transmission efficiency of the signal.

[0091]

[0092] ​​Any combination of the technical features in the above embodiments can be made, and for the sake of brevity, not all possible combinations are described, however, it is to be understood that the scope of protection includes all possible combinations of the technical features.

[0093] The above-described embodiments only express several embodiments of the present specification, which are described in a more specific and detailed manner, but should not be understood as a limitation on the scope of the solutions provided by the embodiments of the present specification. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present specification, and these all belong to the protection scope of the present specification. Therefore, the protection scope of the present specification should be subject to the appended claims.

Claims

1. An acoustic wave device, characterized by, Comprising: a substrate; a piezoelectric layer located on one side of the substrate; an interdigital transducer located on the piezoelectric layer away from the substrate, the distance between the first surface and the second surface is greater than 0.05λ and less than or equal to 1.19λ, λ represents the wavelength of the acoustic wave propagating in the acoustic wave device; the first surface includes the surface of the interdigital transducer away from the piezoelectric layer, and the second surface includes the surface of the piezoelectric layer away from the interdigital transducer.

2. The acoustic wave device according to claim 1, characterized by, The distance between the first surface and the second surface is greater than 0.05λ and less than or equal to 1.1575λ.

3. The acoustic wave device according to claim 2, characterized by The thickness of the interdigital transducer ranges from 0.025λ to 0.2λ.

4. The acoustic wave device according to claim 3, characterized by The thickness of the interdigital transducer ranges from 0.1λ±0.01λ; The distance between the first surface and the second surface is greater than or equal to 0.28λ and less than or equal to 0.2825λ.

5. The acoustic wave device according to any one of claims 1 to 4, characterized by, The thickness of the piezoelectric layer ranges from 0.05λ to 1λ.

6. The acoustic wave device according to any one of claims 1 to 4, wherein The piezoelectric layer includes a recessed area; The interdigital transducer includes a first part and a second part, the second part is arranged in the recessed area, and the first part is arranged outside the recessed area, in a target plane, the cross-sectional shape and / or size of the first part and the second part are different; The target plane includes a plane perpendicular to the first surface and the second surface.

7. The acoustic wave device according to claim 6, wherein, In the target plane, the cross-sectional shape of the first part and the second part includes a rectangle, the long side of the cross section of the second part is smaller than the long side of the cross section of the first part, and the ratio of the long side of the cross section of the second part to the long side of the cross section of the first part is greater than or equal to 20%.

8. The acoustic wave device according to claim 6, wherein, In the target plane, the cross-sectional shape of the second part includes one of an inverted trapezoid and a triangle.

9. The acoustic wave device according to any one of claims 1 to 4, wherein Further comprising: a temperature compensation layer located on the piezoelectric layer away from the substrate, and the temperature compensation layer covers the interdigital transducer.

10. The acoustic wave device according to any one of claims 1 to 4, wherein The interdigital transducer includes a single layer of metal electrodes or multiple layers of metal electrodes arranged in a stack.

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