CN118174679A

CN118174679A - Elastic wave device

Info

Publication number: CN118174679A
Application number: CN202410233485.2A
Authority: CN
Inventors: 傅肃磊; 俞振一; 许志斌; 陆增天; 王为标; 刘平
Original assignee: Wuxi Haoda Electronic Co ltd
Current assignee: Wuxi Haoda Electronic Co ltd
Priority date: 2024-03-01
Filing date: 2024-03-01
Publication date: 2024-06-11

Abstract

The application relates to an elastic wave device, and relates to the technical field of elastic waves. In the elastic wave device provided by the application, the sapphire substrate with the main surface being the a-plane, the c-plane, the m-plane or the r-plane is used as the supporting substrate, the lithium niobate thin film is formed above the sapphire substrate, the lithium niobate thin film is supported, at least the IDT electrode and the reflector electrode are formed on the lithium niobate thin film, and the reflector electrodes are positioned on two sides of the IDT electrode along the elastic wave propagation direction, so that clutter near a main mode caused by a composite multilayer structure based on the piezoelectric thin film can be restrained.

Description

Elastic wave device

Technical Field

The present application relates to the elastic wave technology field, and more particularly, to an elastic wave device capable of suppressing a main mode clutter response.

Background

The elastic wave device has the characteristics of low cost, small volume, multiple functions and the like, and is widely applied to the fields of radar, communication, navigation and the like. The most commonly used elastic wave devices in mobile phone and base station communication are elastic wave resonators, elastic wave filters composed of a plurality of elastic wave resonators, and elastic wave diplexers and elastic wave multiplexers composed of a plurality of elastic wave filters. In any type of elastic wave device, a thin film pattern of a conductive material is provided on a piezoelectric multilayer substrate to determine a plurality of IDT (interdigital transducer) electrodes, and band-pass characteristics are obtained by utilizing frequency characteristics of a conversion function of an electric signal of the IDT electrode into an elastic wave.

Mobile communication systems are evolving from 3G, 4G, to 5G. The 5G communications era has made increasingly stringent demands on the performance of surface acoustic wave filters, such as high frequency, high power, large bandwidth, low loss, etc., and the frequency band used moves to a frequency band above 3 GHz. The traditional surface acoustic wave device is limited by the piezoelectric material, has low Q value and coupling coefficient, and can not fully meet the requirement of mobile communication on the high performance of the device. The surface acoustic wave device based on the composite multilayer structure of the lithium tantalate/lithium niobate piezoelectric film has been attracting attention because of the advantages of low insertion loss, low temperature drift, large bandwidth, high power and the like.

However, the composite multilayer structure based on the piezoelectric film also causes parasitic clutter problems, such as clutter response near the main mode, which worsens the loss and in-band ripple of the filter, and also causes mode crosstalk between the diplexer or the radio frequency module, greatly affecting the performance of the communication device.

In the related art, patent document CN116601871a discloses an elastic wave device capable of suppressing a higher order mode, comprising: a silicon substrate; a polysilicon layer disposed on the silicon substrate; a silicon oxide layer disposed directly or indirectly on the polysilicon layer; a piezoelectric layer directly or indirectly provided on the silicon oxide layer; and an IDT electrode provided on the piezoelectric layer, wherein the surface orientation of the silicon substrate is any one of (100), (110) and (111), and the thickness of the piezoelectric layer is 1 λ or less when a wavelength defined by the electrode finger pitch of the IDT electrode is λ.

However, in the elastic wave device disclosed in patent document CN116601871a, the prescribed substrate is silicon, and the euler angle of the substrate is not limited correspondingly in the patent; the suppressed parasitic clutter is higher order bulk wave clutter; the technical scheme has the advantages that the composite multi-layer structure achieves four layers, and the preparation difficulty of the device is certainly increased.

Disclosure of Invention

The application aims to provide an elastic wave device so as to solve the technical problem of clutter response near a main mode caused by a composite multilayer structure based on piezoelectric films in the prior art.

In order to achieve the above purpose, the application adopts the following technical scheme:

In a first aspect, the present application provides an elastic wave device comprising:

A sapphire substrate having a main surface of a-plane, wherein the euler angle of the sapphire substrate is (90 ° ± 2.5 °,90 ° ± 2.5 °, ψ±2.5 °);

A lithium niobate thin film provided on the sapphire substrate, wherein the thickness of the lithium niobate thin film is equal to or less than λ on the premise that the wavelength of the elastic wave is λ, and the euler angle of the lithium niobate thin film is (0±2.5°, β±2.5°,0±2.5°);

an IDT electrode provided on the lithium niobate thin film; and

Reflector electrodes provided on the lithium niobate thin film, on both sides of the IDT electrode in the propagation direction of the elastic wave;

wherein, when beta in Euler angles of the lithium niobate thin film satisfies 90 DEG-beta < 97 DEG, psi in Euler angles of the sapphire substrate is 15 DEG-phi 60 DEG or 195 DEG-phi 240 DEG;

when beta in Euler angles of the lithium niobate thin film satisfies that beta is not less than 97 DEG and not more than 109 DEG, phi in Euler angles of the sapphire substrate is not less than 0 DEG and not more than 60 DEG or not less than 90 DEG and not more than 240 DEG or not more than 270 DEG and not more than 360 deg.

In a second aspect, the present application provides an elastic wave device comprising:

A sapphire substrate having a c-plane main surface, wherein the euler angle of the sapphire substrate is (0 ° ± 2.5 °,0 ° ± 2.5 °, ψ±2.5 °);

an IDT electrode provided on the lithium niobate thin film; and

Wherein, when beta in Euler angles of the lithium niobate thin film satisfies 90 DEG-beta < 100 DEG, phi in Euler angles of the sapphire substrate is 0 DEG-phi < 30 DEG or 90 DEG-phi < 150 DEG or 210 DEG-phi < 270 DEG or 330 DEG-phi < 360 DEG;

When beta in the Euler angle of the lithium niobate thin film is less than or equal to 100 degrees and less than or equal to 110 degrees, phi in the Euler angle of the sapphire substrate is less than or equal to 15 degrees and less than or equal to 45 degrees or 75 degrees and less than or equal to 105 degrees or 135 degrees and less than or equal to 165 degrees or 195 degrees and less than or equal to 225 degrees or 255 degrees and less than or equal to 285 degrees or 315 degrees and less than or equal to 345 degrees;

When beta in Euler angles of the lithium niobate thin film satisfies 110 DEG-beta-125 DEG, phi in Euler angles of the sapphire substrate is 30 DEG-phi-90 DEG or 150 DEG-phi-210 deg.

In a third aspect, the present application provides an elastic wave device comprising:

a sapphire substrate having m-plane main surfaces, wherein the euler angles of the sapphire substrate are (0 ° ± 2.5 °,90 ° ± 2.5 °, ψ±2.5 °);

an IDT electrode provided on the lithium niobate thin film; and

Wherein, when beta in Euler angles of the lithium niobate thin film satisfies 90 DEG-beta < 100 DEG, phi in Euler angles of the sapphire substrate is 20 DEG-phi 60 DEG-phi or 70 DEG-phi 100 DEG-phi or 140 DEG-phi 220 DEG-phi or 260 DEG-phi 290 DEG-phi or 300 DEG-phi 340 DEG-phi;

When beta in the Euler angle of the lithium niobate thin film satisfies that beta is not less than 100 DEG and not more than 120 DEG, phi in the Euler angle of the sapphire substrate is not less than 0 DEG and not more than 30 DEG or not more than 75 DEG and not more than 105 DEG or not more than 120 DEG and not more than 180 DEG or not more than 255 DEG and not more than 285 DEG or not more than 330 DEG and not more than 360 deg.

In a fourth aspect, the present application provides an elastic wave device comprising:

A sapphire substrate having a main surface of r-plane, wherein the euler angle of the sapphire substrate is (0 ° ± 2.5 °,123.23 ° ± 2.5 °, ψ±2.5 °);

an IDT electrode provided on the lithium niobate thin film; and

Wherein, when beta in Euler angles of the lithium niobate thin film satisfies 90 DEG-beta < 100 DEG, phi in Euler angles of the sapphire substrate is 25 DEG-phi and less than or equal to 90 DEG or 145 DEG-phi and less than or equal to 160 DEG or 200 DEG-phi and less than or equal to 215 DEG or 270 DEG-phi and less than or equal to 335 DEG;

when beta in the Euler angle of the lithium niobate thin film meets the condition that beta is more than or equal to 100 degrees and less than or equal to 110 degrees, phi in the Euler angle of the sapphire substrate is more than or equal to 0 degree and less than or equal to 45 degrees or more than or equal to 80 degrees and less than or equal to 155 degrees or more than or equal to 205 degrees and less than or equal to 280 degrees or more than or equal to 315 degrees and less than or equal to 360 degrees;

When beta in Euler angles of the lithium niobate thin film satisfies 110 DEG beta not more than 130 DEG, phi in Euler angles of the sapphire substrate is 0 DEG phi not more than 30 DEG or 95 DEG phi not more than 145 DEG or 215 DEG phi not more than 265 DEG or 330 DEG phi not more than 360 deg.

In a fifth aspect, the present application provides a filter or multiplexer having a series-arm resonator and a parallel-arm resonator, wherein:

the series-arm resonator and the parallel-arm resonator include the elastic wave device according to any one of the above.

The technical scheme provided by the application has the beneficial effects that at least:

A lithium niobate thin film is formed on a sapphire substrate having a main surface of an a-plane, a c-plane, an m-plane, or an r-plane as a support substrate, and is supported by the support substrate, and at least an IDT electrode and a reflector electrode are formed on the lithium niobate thin film, the reflector electrodes being located on both sides of the IDT electrode in the elastic wave propagation direction, whereby noise in the vicinity of a main mode due to a composite multilayer structure of a piezoelectric thin film can be suppressed.

Drawings

The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate the application and together with the embodiments of the application, serve to explain the application. In the drawings:

FIG. 1 shows a schematic top view and a cross-sectional view of a typical piezoelectric composite substrate based Surface Acoustic Wave (SAW) resonator;

FIG. 2 shows an admittance/conductance-frequency plot for a typical piezoelectric composite substrate based Surface Acoustic Wave (SAW) resonator;

FIG. 3 shows a phase-frequency plot of a typical Surface Acoustic Wave (SAW) resonator based on a piezoelectric composite substrate;

FIG. 4 shows a definition of the crystallographic axis of sapphire and schematic diagrams of the a-plane, m-plane, c-plane and r-plane of sapphire;

Fig. 5 shows a cross-sectional view of an elastic wave device 200 provided in a comparative example of the present application;

FIG. 6 shows an admittance/conductance-frequency plot of an elastic wave device 200 provided in accordance with a comparative example of the present application;

Fig. 7 is a diagram showing a vibration mode of a main mode of an elastic wave device 200 according to a comparative example of the present application;

FIG. 8 is a diagram showing a vibration mode of clutter one of the elastic wave device 200 according to the comparative example one of the present application;

FIG. 9 is a diagram showing a vibrational mode of a clutter second embodiment of a first embodiment of the present application providing a typical elastic wave device 200;

FIG. 10 shows a phase-frequency plot of an elastic wave device 200 provided in comparative example one of the present application;

FIG. 11 is a graph showing the variation of electromechanical coupling coefficient of the elastic wave device 200 according to the comparative example one of the present application with the thickness hLN of the lithium niobate thin film;

FIG. 12 is a graph showing the maximum phase of spurious responses of an elastic wave device according to an embodiment of the present application as a function of ψ;

FIG. 13 is a graph showing the maximum phase of spurious responses of an elastic wave device as a function of ψ and β in accordance with an embodiment of the present application;

FIG. 14 is a graph showing the maximum phase of spurious response of an elastic wave device according to the second embodiment of the present application as a function of ψ;

FIG. 15 is a graph showing the maximum phase of spurious responses of an elastic wave device according to second embodiment of the present application as a function of ψ and β;

FIG. 16 is a graph showing the maximum phase of spurious responses of an elastic wave device according to third embodiment of the present application as a function of ψ;

FIG. 17 is a graph showing the maximum phase of spurious responses of an elastic wave device as a function of ψ and β, provided by a third embodiment of the present application;

FIG. 18 is a graph showing the maximum phase of spurious responses of an elastic wave device according to fourth embodiment of the present application as a function of ψ;

FIG. 19 is a graph showing the maximum phase of spurious responses of an elastic wave device according to fourth embodiment of the present application as a function of ψ and β;

FIG. 20 is a graph showing the variation of maximum phase of spurious response of an elastic wave device having a lithium niobate thin film thickness hLN of 0.1λ to 0.4λ with respect to ψ;

FIG. 21 shows a graph of the maximum phase of the spurious response of an elastic wave device as a function of hLN and ψ simultaneously;

FIGS. 22 and 23 show schematic diagrams of the elastic wave device as a function of ψ in actual preparation;

fig. 24 shows admittance/phase-frequency curves of different ψ for an actually prepared elastic wave device;

Fig. 25 shows a cross-sectional view of an elastic wave device 300 according to a first modification of the present application;

fig. 26 shows a cross-sectional view of an elastic wave device 400 according to a second modification of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

Wherein like parts are designated by like reference numerals. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the drawings of the present application, and the words "bottom" and "top", "inner" and "outer" refer to directions toward or away from, respectively, a specific component. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present specification, the meaning of "plurality" is two or more.

The application will be further described with reference to the drawings and examples.

Device description:

Fig. 1 shows a schematic top view and a cross-sectional view of a typical Surface Acoustic Wave (SAW) resonator based on a piezoelectric composite substrate. In recent years, SAW resonators based on a piezoelectric composite substrate of a lithium niobate thin film 1 and a non-piezoelectric substrate 3 have been attracting attention due to their high Q value, large electromechanical coupling coefficient performance, and are being applied to a wide variety of fields such as radar, communication, navigation, and the like.

The SAW resonator based on the piezoelectric composite substrate is composed of a lithium niobate thin film 1 and a thin film pattern of conductive material formed on the piezoelectric composite substrate other than the piezoelectric substrate 3. The lithium niobate thin film 1 is a thin single crystal layer made of a piezoelectric material, and has a thickness h, wherein the piezoelectric material is lithium niobate, lithium tantalate, gallium nitride, aluminum nitride or zinc oxide. As a matter of common knowledge, the lithium niobate thin film 1 is cut so as to coincide with crystal axes of the front and back sides of the opposite lithium niobate thin film 1, so that the lithium niobate thin film 1 has different tangential selections, and we often define its tangential direction by using euler angles, for example, 15 ° Y-cut lithium niobate thin film euler angles are (0 °,105 °,0 °), Z-cut lithium niobate thin film euler angles are (0 °,0 °,0 °), 128 ° Y-cut lithium niobate thin film euler angles are (0 °,38 °,0 °), 32 ° Y45 ° X-cut lithium niobate thin film euler angles are (0 °,122 °,45 °).

Admittance:

Admittance is a physical quantity that describes the response of a circuit element to alternating current and voltage, and is generally represented by the symbol Y. For a circuit element, its admittance Y consists of a real part (conductance G) and an imaginary part (susceptance B), i.e. y=g+jb, where j is an imaginary unit. In the present embodiment, the admittance (dB) can be obtained by the formula y=20×log ₁₀ |y|.

The non-piezoelectric substrate 3 is a single-layer or multi-layer substrate made of a high acoustic-velocity material, and is therefore also called a high acoustic-velocity member in which the acoustic velocity of bulk waves propagating in the high acoustic-velocity member is higher than that of elastic waves propagating in the lithium niobate thin film, so that the acoustic velocity of elastic waves in the lithium niobate thin film can be raised, and the frequency of the device can be raised. In addition, the high sound velocity component can effectively seal the elastic wave propagated in the lithium niobate thin film without leakage, thereby improving the Q value of the device.

The high sound velocity member is composed of a material having a relatively high sound velocity, such as silicon, sapphire, silicon carbide, aluminum nitride, or the like. Table 1 shows the sound speeds of 3 different modes of elastic waves in various materials.

Table 1:

Fig. 2 shows an admittance/conductance-frequency plot for a typical Surface Acoustic Wave (SAW) resonator based on a piezoelectric composite substrate. From the curve it is known that the resonator has a resonance frequency of 1899MHz, an antiresonance frequency of 2199MHz and an electromechanical coupling coefficient of 33.7% and that there is substantially no spurious response in the passband.

Electromechanical coupling coefficient:

The electromechanical coupling coefficient can be obtained by the formula K ²＝π²/4×(f_p-f_s)/f_p on the premise that the resonance frequency of the resonator is f _s and the antiresonance frequency is f _p.

The quantitative measurement of the spurious response of a resonator is typically represented by the phase-frequency curve of the resonator. Fig. 3 shows a phase-frequency plot of a typical Surface Acoustic Wave (SAW) resonator based on a piezoelectric composite substrate. The phase between the resonance frequency and the antiresonance frequency of the resonator without spurious response is maintained at about-90 deg., and when spurious response occurs, the phase between the resonance frequency and antiresonance frequency will be abrupt, the amplitude of the abrupt change representing the intensity of the spurious response. In general, the larger the amplitude of the abrupt change, the stronger the spurious response; conversely, the weaker the spurious response. As shown in fig. 3, the change in resonator phase is only 3 °, indicating that the spurious response is in an extremely weak state and does not affect the performance of the resonator.

The commercial sapphire substrate widely used at present has four crystal faces of an a-plane, an m-plane, a c-plane and an r-plane, and the sapphire and lithium niobate thin films of different crystal faces are combined to have different performances due to the anisotropy of crystal materials. Fig. 4 shows a definition of the sapphire crystal axis and schematic diagrams of the a-plane, m-plane, c-plane, and r-plane of sapphire.

In the present embodiment, the non-piezoelectric substrate 3 is a sapphire substrate. The sapphire is a single crystal of hexagonal structure, and the α ₁ axis, the α ₂ axis, and the α ₃ axis are equivalent, respectively, due to symmetry of the crystal structure on the premise that the crystal axis of the sapphire is (α ₁,α₂,α₃, C).

The main surface of the sapphire substrate may have an a-plane, an m-plane, a c-plane, or an r-plane.

When the main surface of the sapphire substrate is the a-plane, the main surface of the sapphire substrate on the lithium niobate thin film 1 side is the (11-20) plane. The (11-20) plane is a plane perpendicular to the crystal axis represented by the Miller index [11-20] in the crystal structure. In this state, the propagation angle ψ of an elastic wave in the sapphire substrate is an angle formed by the propagation direction of the elastic wave and the crystal orientation [0001] of the miller index of the sapphire when viewed from the side of the main surface of the lithium niobate thin film 1 where the IDT electrode 2a is formed as shown in fig. 1. Here, the euler angle of the sapphire substrate is set to beIn addition, ψ in the euler angles is the propagation angle ψ described above. In the case where the (11-20) plane is represented by the Euler angle, it is (90 DEG, ψ).

When the principal surface of the sapphire substrate is the c-plane, the principal surface of the sapphire substrate on the lithium niobate thin film 1 side is the (0001) plane. In this state, the propagation angle ψ of the sapphire substrate is an angle formed by the propagation direction of the elastic wave and the crystal orientation [1000] of the miller index of the sapphire when viewed from the side of the main surface of the lithium niobate thin film 1 where the IDT electrode 2a is formed as shown in fig. 1. When the (0001) plane is expressed by the euler angle, it is (0 °,0 °, ψ).

When the principal surface of the sapphire substrate is an m-plane, the principal surface of the sapphire substrate on the lithium niobate thin film 1 side is a (1-100) plane. In this state, the propagation angle ψ of the sapphire substrate is an angle formed by the propagation direction of the elastic wave and the crystal orientation [0001] of the miller index of the sapphire when viewed from the side of the main surface of the lithium niobate thin film 1 where the IDT electrode 2a is formed as shown in fig. 1. In the case where the (1-100) plane is represented by the Euler angle, it is (0 °,90 °, ψ).

When the main surface of the sapphire substrate is the r-plane, the main surface of the sapphire substrate on the lithium niobate thin film 1 side is the (1-102) plane. In this state, the propagation angle ψ of the sapphire substrate is an angle formed by the propagation direction of the elastic wave and the crystal orientation [1-10-1] of the miller index of the sapphire when viewed from the side of the main surface of the lithium niobate thin film 1 where the IDT electrode 2a is formed as shown in fig. 1. In the case where the (1-102) plane is represented by the Euler angle, it is (0 °,122.23 °, ψ).

As shown in fig. 1, the conductive material film pattern includes IDT (interdigital transducer) electrodes 2a, reflector electrodes 2b, interdigital transducer bus bars 4a, and reflector bus bars 4b, which have a thickness h _m. The IDT electrode 2a includes a plurality of first electrode fingers and a plurality of second electrode fingers inserted alternately, and a first bus bar and a second bus bar opposing each other in the extending direction of the first electrode fingers and the second electrode finger fingers. The distance λ between adjacent first (or second) electrode fingers is commonly referred to as the "wavelength" of the IDT. The first and second electrode fingers overlap by a distance AP, which is commonly referred to as the "aperture" of the IDT. The reflector electrode 2b includes a plurality of third electrode fingers and a plurality of fourth electrode fingers interposed alternately with each other, and third bus bars and fourth bus bars opposed to each other in the extending direction of the third electrode fingers, the fourth electrode fingers, and the fingers.

Comparative example one:

Fig. 5 shows a cross-sectional view of an elastic wave device 200 provided in a comparative example of the present application. The high acoustic velocity member 5 is a sapphire substrate of a-plane, c-plane, m-plane or r-plane, over which a lithium niobate film 1 is formed, and supports the lithium niobate film 1, over which a conductive material film pattern including IDT electrodes 2a, reflector electrodes 2b, IDT bus bars (not shown) and reflector bus bars (not shown) is formed. A direction parallel to the x-axis in the coordinate system is defined as an electrode finger arrangement direction, which is also an elastic wave propagation direction, a direction parallel to the y-axis in the coordinate system is defined as an electrode finger extending direction (not shown in the figure), and a direction parallel to the z-axis in the coordinate system is defined as a height direction of the elastic wave device 200.

Fig. 6 shows an admittance/conductance-frequency graph of an elastic wave device 200 provided in comparative example one of the present application. As can be seen from the figure, the main mode of the elastic wave device 200 has a resonance frequency of 2136MHz and an antiresonance frequency of 2409MHz, and the electromechanical coupling coefficient is 28%. Clutter one has a resonance frequency of 2163MHz and clutter two has a resonance frequency of 2313 MHz. Clutter one and two occur near the primary mode, between the primary mode resonant frequency and the anti-resonant frequency, severely degrading the performance of the elastic wave device 200.

Fig. 7 shows a vibration mode diagram of a main mode of an elastic wave device 200 provided in a comparative example of the present application. As can be seen from the modal diagram, this is a typical Shear Horizontal (SH) wave mode. Fig. 8 and 9 also show vibration mode diagrams of clutter one and two, respectively.

Fig. 10 shows a phase-frequency plot of an elastic wave device 200 provided in comparative example one of the present application. It can be seen from the figure that the phase between the resonant frequency and the antiresonant frequency of the elastic wave device 200 is maximally abrupt to-12 °, and the amplitude of the change reaches 78 °, which indicates that the elastic wave device 200 has an extremely strong spurious response near the main mode, severely damaging its performance. The-12 DEG is defined as the maximum phase of the spurious response of the resonator, so as to analyze the variation of the spurious response.

Fig. 11 is a graph showing the variation of electromechanical coupling coefficient of the elastic wave device 200 according to the comparative example of the present application with the thickness h _LN of the lithium niobate thin film. Sapphire with a surface, an m surface and an r surface are respectively selected as the sapphire substrate, psi is 0 degrees, and the wavelength of elastic waves is lambda. As is clear from the graph, when h _LN is equal to or less than 0.3λ, the electromechanical coupling coefficient of the elastic wave device 200 increases as h _LN increases, and when h _LN is greater than 0.3λ, the electromechanical coupling coefficient of the elastic wave device 200 remains stable and is maintained at about 34%.

Embodiment one:

the elastic wave device according to the first embodiment is substantially identical to the elastic wave device 200 according to the first comparative example, except that:

The lithium niobate thin film 1 is lithium niobate, the Euler angle is (0 degree, beta, 0 degree), and the thickness is h _LN;

the conductive film material pattern is formed by an aluminum electrode, and the thickness h _m is 8 percent lambda;

the wavelength of the elastic wave is lambda, and the thickness of the lithium niobate thin film is h _LN;

The high sound velocity member 4 uses a sapphire substrate having a main surface of a plane, and has an euler angle (90 °,90 °, ψ).

Fig. 12 is a graph showing a variation of maximum phase of spurious response of an elastic wave device according to an embodiment of the present application with respect to ψ. In detail, h _LN is 0.3λ and β is 105 °. When the maximum phase is less than-70 deg., the spurious response of the elastic wave device is at an acceptable level and the performance of the resonator is not greatly affected. According to the graph, when 0 DEG.ltoreq.ψ.ltoreq.30 DEG or 90 DEG.ltoreq.ψ.ltoreq.115 DEG or 155 DEG.ltoreq.ψ.ltoreq.210 DEG or 270 DEG.ltoreq.ψ.ltoreq.295 DEG or 335 DEG.ltoreq.ψ.ltoreq.360 DEG, the maximum phase of the spurious response of the elastic wave device is less than-70 DEG, and the spurious response is weak.

Fig. 13 is a graph showing the maximum phase of spurious responses of an elastic wave device according to the first embodiment of the present application as a function of ψ and β. In detail, h _LN is 0.3λ. When the maximum phase is less than-70 deg. (i.e. the dark part of the figure), the spurious response of the elastic wave device is at an acceptable level and the performance of the resonator is not significantly affected. From the graph, when beta is more than or equal to 97 degrees and less than or equal to 109 degrees, phi is more than or equal to 0 degrees and less than or equal to 60 degrees or is more than or equal to 90 degrees and less than or equal to 240 degrees or is more than or equal to 270 degrees and less than or equal to 360 degrees; or when beta is more than or equal to 90 degrees and less than 97 degrees, phi is more than or equal to 15 degrees and less than or equal to 60 degrees or phi is more than or equal to 195 degrees and less than or equal to 240 degrees, the maximum phase of the spurious response of the elastic wave device is less than-70 degrees, and the spurious response is weaker.

Embodiment two:

The elastic wave device provided in the second embodiment is substantially identical to the elastic wave device 200 provided in the first comparative example, except that:

The high sound velocity member 4 uses a sapphire substrate having a c-plane main surface, and has an euler angle (0 °,0 °, ψ).

Fig. 14 is a graph showing a variation of maximum phase of spurious response of an elastic wave device according to the second embodiment of the present application with respect to ψ. In detail, h _LN is 0.3λ and β is 105 °. When the maximum phase is less than-70 deg., the spurious response of the elastic wave device is at an acceptable level and the performance of the resonator is not greatly affected. According to the graph, when 30 DEG.ltoreq.PSI.ltoreq.45 DEG or 75 DEG.ltoreq.PSI.ltoreq.90 DEG or 150 DEG.ltoreq.PSI.ltoreq.165 DEG or 195 DEG.ltoreq.PSI.ltoreq.210 DEG or 270 DEG.ltoreq.PSI.ltoreq.285 DEG or 315 DEG.ltoreq.PSI.ltoreq.330 DEG, the maximum phase of the spurious response of the elastic wave device is less than-70 DEG, and the spurious response is weak.

Fig. 15 shows a graph of maximum phase of spurious responses of an elastic wave device according to a second embodiment of the present application as a function of ψ and β. In detail, h _LN is 0.3λ. When the maximum phase is less than-70 deg. (i.e. the dark part of the figure), the spurious response of the elastic wave device is at an acceptable level and the performance of the resonator is not significantly affected. From the graph, when the beta is more than or equal to 110 degrees and less than or equal to 125 degrees, the phi is more than or equal to 30 degrees and less than or equal to 90 degrees or the phi is more than or equal to 150 degrees and less than or equal to 210 degrees; or when beta is more than or equal to 100 degrees and less than 110 degrees, phi is more than or equal to 15 degrees and less than or equal to 45 degrees or phi is more than or equal to 75 degrees and less than or equal to 105 degrees or is less than or equal to 135 degrees and less than or equal to 165 degrees or is less than or equal to 195 degrees and less than or equal to 225 degrees or is less than or equal to 255 degrees and is less than or equal to 285 degrees or is less than or equal to 315 degrees and less than or equal to 345 degrees; or when 90 DEG.beta.less than 100 DEG, 0 DEG.phi.less than or equal to 30 DEG or 90 DEG.phi.less than or equal to 150 DEG or 210 DEG.phi.less than or equal to 270 DEG or 330 DEG.phi.less than or equal to 360 DEG, the maximum phase of the spurious response of the elastic wave device is less than-70 DEG, and the spurious response is weaker.

Embodiment III:

the elastic wave device according to the third embodiment is substantially identical to the elastic wave device 200 according to the first comparative example, except that:

The high sound velocity member 4 uses a sapphire substrate having an m-plane main surface, and has an euler angle (0 °,90 °, ψ).

Fig. 16 is a graph showing the variation of the maximum phase of the spurious response of the elastic wave device according to the third embodiment of the present application with respect to ψ. In detail, h _LN is 0.3λ and β is 105 °. When the maximum phase is less than-70 deg., the spurious response of the elastic wave device is at an acceptable level and the performance of the resonator is not greatly affected. According to the graph, when 10 DEG.ltoreq.ψ.ltoreq.25 DEG or 85 DEG.ltoreq.ψ.ltoreq.110 DEG or 130 DEG.ltoreq.ψ.ltoreq.160 DEG or 200 DEG.ltoreq.ψ.ltoreq.230 DEG or 250 DEG.ltoreq.ψ.ltoreq.275 DEG or 335 DEG.ltoreq.350 DEG, the maximum phase of the spurious response of the elastic wave device is less than-70 DEG, and the spurious response is weak.

Fig. 17 shows a graph of maximum phase of spurious responses of an elastic wave device according to third embodiment of the present application as a function of ψ and β. In detail, h _LN is 0.3λ. When the maximum phase is less than-70 deg. (i.e. the dark part of the figure), the spurious response of the elastic wave device is at an acceptable level and the performance of the resonator is not significantly affected. From the graph, when beta is more than or equal to 100 degrees and less than or equal to 120 degrees, phi is more than or equal to 0 degrees and less than or equal to 30 degrees or is more than or equal to 75 degrees and less than or equal to 105 degrees or is more than or equal to 120 degrees and less than or equal to 180 degrees or is more than or equal to 255 degrees and less than or equal to 285 degrees or is less than or equal to 330 degrees and less than or equal to 360 degrees; or when 90 DEG.beta.less than 100 DEG, 20 DEG.phi.less than 60 DEG or 70 DEG.phi.less than 100 DEG or 140 DEG.phi.less than 220 DEG or 260 DEG.phi.less than 290 DEG or 300 DEG.phi.less than 340 DEG, the maximum phase of the spurious response of the elastic wave device is less than-70 DEG, and the spurious response is weaker.

Embodiment four:

the elastic wave device according to the fourth embodiment is substantially identical to the elastic wave device 200 according to the first comparative example, except that:

The high sound velocity member 4 uses a sapphire substrate having a main surface of r plane, and has an euler angle of (0 °,122.23 °, ψ).

Fig. 18 is a graph showing the variation of the maximum phase of the spurious response of the elastic wave device according to the fourth embodiment of the present application with respect to ψ. In detail, h _LN is 0.3λ and β is 105 °. When the maximum phase is less than-70 deg., the spurious response of the elastic wave device is at an acceptable level and the performance of the resonator is not greatly affected. According to the graph, when the angle phi is more than or equal to 20 degrees and less than or equal to 35 degrees or more than or equal to 90 degrees and less than or equal to 105 degrees or more than or equal to 135 degrees and less than or equal to 150 degrees or more than or equal to 210 degrees and less than or equal to 225 degrees or more than or equal to 255 degrees and less than or equal to 270 degrees or 325 degrees and less than or equal to 340 degrees, the maximum phase of the spurious response of the elastic wave device is less than-70 degrees, and the spurious response is weaker.

Fig. 19 shows a graph of maximum phase of spurious responses of an elastic wave device according to fourth embodiment of the present application as a function of ψ and β. In detail, h _LN is 0.3λ. When the maximum phase is less than-70 deg. (i.e. the dark part of the figure), the spurious response of the elastic wave device is at an acceptable level and the performance of the resonator is not significantly affected. From the graph, when 110 DEG.beta.ltoreq.130 DEG, 0 DEG.ltoreq.psi.ltoreq.30 DEG or 95 DEG.ltoreq.psi.ltoreq.145 DEG or 215 DEG.ltoreq.psi.ltoreq.265 DEG or 330 DEG.ltoreq.psi.ltoreq.360 DEG; or when beta is more than or equal to 100 degrees and less than 110 degrees, phi is more than or equal to 0 degrees and less than or equal to 45 degrees or phi is more than or equal to 80 degrees and less than or equal to 155 degrees or is more than or equal to 205 degrees and less than or equal to 280 degrees or is more than or equal to 315 degrees and less than or equal to 360 degrees; or when beta is more than or equal to 90 degrees and less than 100 degrees, phi is more than or equal to 25 degrees and less than or equal to 90 degrees or phi is more than or equal to 145 degrees and less than or equal to 160 degrees or is more than or equal to 200 degrees and less than or equal to 215 degrees or is more than or equal to 270 degrees and less than or equal to 335 degrees, the maximum phase of spurious response of the elastic wave device is less than-70 degrees, and the spurious response is weaker.

The above examples are based on a lithium niobate thin film thickness h _LN of 0.3λ, however, it should be noted that the variation of the lithium niobate thin film thickness also has an effect on the proper angular range of ψ. Fig. 20 shows a graph of the maximum phase of the spurious response of the elastic wave device with a lithium niobate thin film thickness h _LN of 0.1λ to 0.4λ as a function of ψ. Wherein, sapphire with the main surface of c-plane is selected as the sapphire substrate. As can be seen from the graph, the sensitivity of spurious response to change in ψ is also different for the elastic wave devices with different lithium niobate film thicknesses.

To further illustrate this variation, FIG. 21 shows a plot of the maximum phase of the spurious response of the elastic wave device as a function of both h _LN and ψ. As can be seen, as h _LN increases, the appropriate range of ψ (i.e. the dark black portion of the figure) increases gradually.

Therefore, for the elastic wave device, as the thickness of the lithium niobate thin film increases, the ψ proper range of sapphire for spurious response suppression is also appropriately expanded. In other words, the thicker the lithium niobate thin film is, the more favorable the suppression of the stray mode by ψ is. The application realizes clutter suppression of LN with different thickness through sapphires with different surfaces.

Fig. 22 and 23 show schematic diagrams of the elastic wave device as a function of ψ in actual production. When the psi is 0 DEG, the trimming edge of the sapphire substrate is the same as the propagation direction of the elastic wave device; when ψ is 90 °, the cut edge of the sapphire substrate and the elastic wave propagation direction of the elastic wave device are 90 °. In the practical implementation process, in order to obtain the elastic wave device meeting the requirements, the sapphire substrate can be processed and prepared in an in-plane rotation mode to obtain different psi propagation angles.

Fig. 24 shows admittance/phase-frequency curves of different ψ of an actually prepared elastic wave device. Wherein, sapphire with the main surface of c surface is selected as the sapphire substrate, and the thickness h _LN of the lithium niobate thin film is 0.3λ. As for the sapphire substrate with the c-plane phi of 0 degrees, the elastic wave device has larger spurious response near the main mode, and the maximum phase of the spurious response reaches 80 degrees; for the sapphire substrate with the c-plane phi of 90 degrees, larger spurious response does not exist near the main mode of the elastic wave device, and the maximum phase of the spurious response is only-85 degrees.

Thus, in the actual manufacturing process, the larger spurious response near the main mode of the resonator can be suppressed by the processing manufacturing method described above and in the examples.

Modification one:

Fig. 25 shows a cross-sectional view of an elastic wave device 300 according to a first modification of the present application. The high acoustic velocity member 5 is a sapphire substrate of a-plane, c-plane, m-plane or r-plane, over which a low acoustic velocity material layer 6 is formed and which supports the lithium niobate thin film 1, and over which a conductive material thin film pattern including IDT electrodes 2a, reflector electrodes 2b, IDT bus bars (not shown) and reflector bus bars (not shown) is formed over the lithium niobate thin film 1. A direction parallel to the x-axis in the coordinate system is defined as an electrode finger arrangement direction, which is also an elastic wave propagation direction, a direction parallel to the y-axis in the coordinate system is defined as an electrode finger extending direction (not shown in the figure), and a direction parallel to the z-axis in the coordinate system is defined as a height direction of the elastic wave device 300.

In detail, the lithium niobate thin film 1 is lithium niobate, the Euler angle is (0 degree, beta, 0 degree), and the thickness is h _LN;

the low acoustic velocity material layer 6 is silicon dioxide.

The structural differences from the elastic wave device provided in the above embodiment are: a low sound velocity material layer exists between the sapphire substrate and the lithium niobate thin film.

For the same reason as in the first, second, third or fourth embodiments, the present modification structure can exhibit a good main mode vicinity clutter suppression function.

Modification II:

Fig. 26 shows a cross-sectional view of an elastic wave device 400 according to a second modification of the present application. The high sound velocity member 5 is a sapphire substrate of a-plane, c-plane, m-plane or r-plane, a trapping material layer 7 is formed above the trapping material layer 7, a low sound velocity material layer 6 is formed above the trapping material layer 7, and supports the lithium niobate thin film 1, and a conductive material thin film pattern including IDT electrodes 2a, reflector electrodes 2b, IDT bus bars (not shown) and reflector bus bars (not shown) is formed above the lithium niobate thin film 1. A direction parallel to the x-axis in the coordinate system is defined as an electrode finger arrangement direction, which is also an elastic wave propagation direction, a direction parallel to the y-axis in the coordinate system is defined as an electrode finger extending direction (not shown in the figure), and a direction parallel to the z-axis in the coordinate system is defined as a height direction of the elastic wave device 400.

the low acoustic velocity material layer 6 is silicon dioxide.

The differences from the first modification are: a trapping material layer is present between the sapphire substrate and the low acoustic velocity material layer.

In the embodiments disclosed herein, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and for example, "connected" may be a fixed connection, a removable connection, or an integral connection; "coupled" may be directly coupled or indirectly coupled through intermediaries. The specific meaning of the above terms in the embodiments of the present disclosure will be understood by those of ordinary skill in the art according to the specific circumstances.

The foregoing is only a preferred embodiment of the application, it being noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present application, and such modifications and adaptations are intended to be comprehended within the scope of the application.

Claims

1. An elastic wave device, comprising:

an IDT electrode provided on the lithium niobate thin film; and

2. An elastic wave device, comprising:

an IDT electrode provided on the lithium niobate thin film; and

3. An elastic wave device, comprising:

an IDT electrode provided on the lithium niobate thin film; and

4. An elastic wave device, comprising:

an IDT electrode provided on the lithium niobate thin film; and

5. The elastic wave device according to any one of claims 1 to 4, wherein:

the elastic wave device is further provided with a low-sound-velocity material layer, and the low-sound-velocity material layer is arranged between the sapphire substrate and the lithium niobate thin film.

6. The elastic wave device according to claim 5, wherein:

The elastic wave device further includes a trapping material layer disposed between the sapphire substrate and the low acoustic velocity material layer.

7. The elastic wave device according to any one of claims 1 to 4, wherein:

The thickness of the lithium niobate thin film is 0.05λ or more on the premise that the wavelength of the elastic wave is λ.

8. The elastic wave device according to claim 5 or 6, wherein:

the sound velocity of bulk waves propagating in the low sound velocity material layer is lower than that of bulk waves propagating in the lithium niobate thin film;

The sound velocity of bulk waves propagating in the sapphire substrate is higher than that of bulk waves propagating in the lithium niobate thin film.

9. The elastic wave device according to any one of claims 1 to 4, wherein:

the IDT electrode is formed by laminating one or more metal material films.

10. A filter or multiplexer having a series arm resonator and a parallel arm resonator, wherein:

The series-arm resonator and the parallel-arm resonator include the elastic wave device according to any one of claims 1 to 9.