Elastic wave device, filter device, and multiplexer

Abstract

The invention relates to an elastic wave device, a filter device and a multiplexer, and relates to the field of elastic waves. A silicon substrate with the horizontal shear wave curvature smaller than-0.58 is arranged, a piezoelectric layer is arranged on the silicon substrate, the Euler angle of the piezoelectric layer is (0 + / -2.5 degrees, beta + / -2.5 degrees and 0 + / -2.5 degrees), beta is larger than or equal to 90 degrees and smaller than or equal to 150 degrees, and an interdigital transducer is arranged on the piezoelectric layer. In this case, a large-bandwidth elastic wave device capable of suppressing an intrinsic lateral mode is provided.

Description

Technical Field

[0001] The present application relates to the field of elastic wave technology, and in particular to an elastic wave device, a filter device and a multiplexer. Background Art

[0002] Elastic wave devices have the characteristics of low cost, small size and multiple functions, and have been widely used in radar, communication, navigation and other fields. The most commonly used elastic wave devices in mobile phone and base station communications are elastic wave resonators, elastic wave filters composed of multiple elastic wave resonators, and elastic wave duplexers and elastic wave multiplexers composed of multiple elastic wave filters. In any type of elastic wave device, a conductive material film pattern is set on a piezoelectric multilayer substrate to determine a number of interdigital transducer (IDT) electrodes, and the frequency characteristics of the conversion function of converting the electrical signal of the IDT electrode into elastic waves are used to obtain the bandpass characteristics.

[0003] Mobile communication systems are developing from 3G and 4G to 5G. The 5G communication era places increasingly stringent requirements on the performance of elastic wave filters, such as high frequency, high power, large bandwidth, and low loss. Traditional elastic wave devices are subject to the limitations of piezoelectric materials themselves, with low Q values ​​and coupling coefficients, and cannot fully meet the high performance requirements of mobile communications devices. Elastic wave devices based on the composite multilayer structure of lithium tantalate / lithium niobate piezoelectric films have attracted much attention due to their advantages of low insertion loss, low temperature drift, large bandwidth, and high power.

[0004] As a frequency source device, elastic wave filters usually have spurious waves caused by transverse modes, which cause large fluctuations in the band and large losses, that is, lead to reduced filter performance. The industry usually uses different weighted interdigital transducer electrodes to suppress the generation of transverse modes, but this method also has certain problems: first, the Q value of the device itself will be reduced due to the weighting of the interdigital transducer electrodes, which will increase the loss of the elastic wave filter and hinder its application in the RF front end; second, the weighting method often leads to an increase in the size of the device, hindering the development of device miniaturization; third, some weighting methods will increase the difficulty of device preparation. Summary of the invention

[0005] The purpose of the present application is to provide an elastic wave device, a filter device and a multiplexer to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above purpose, the technical solution adopted in this application is:

[0007] In a first aspect, the present application provides an elastic wave device, comprising:

[0008] Silicon substrate, whose horizontal shear wave curvature is less than -0.58;

[0009] A piezoelectric layer, which is disposed on the silicon substrate, and has an Euler angle of (0±2.5°, β±2.5°, 0±2.5°), wherein β satisfies 90°≤β≤150°; and

[0010] The interdigital transducer is arranged on the piezoelectric layer.

[0011] In a possible implementation, the Euler angle of the silicon substrate is set to (0°, 0°, ψ); wherein ψ satisfies -15°+n×90°≤ψ≤15°+n×90°, and n is an integer.

[0012] In a possible implementation, the Euler angle of the silicon substrate is set to (135°, 90°, ψ); wherein ψ satisfies 80°+n×180°≤ψ≤100°+n×180°, and n is an integer.

[0013] In a possible implementation manner, the speed of sound propagation in the silicon substrate is higher than the speed of sound propagation in the piezoelectric layer.

[0014] In a possible implementation, the IDT is formed by stacking one or more metal material films.

[0015] In a possible implementation manner, a low acoustic velocity layer is further provided between the silicon substrate and the piezoelectric layer.

[0016] In a possible implementation, the low acoustic velocity layer is composed of one or more combinations of relatively low acoustic velocity materials such as silicon dioxide, glass, silicon oxynitride, tantalum oxide, or silicon dioxide with compounds containing fluorine, carbon, or boron as main components added thereto.

[0017] In a possible implementation, the IDT further has reflectors on both sides along the propagation direction of the elastic wave.

[0018] In a second aspect, the present application provides a filter device having:

[0019] a series arm resonator; and a parallel arm resonator,

[0020] At least one of the series arm resonator and the parallel arm resonator is the elastic wave device as described above.

[0021] In a third aspect, the present application provides a multiplexer having:

[0022] an antenna terminal connected to an antenna; and

[0023] A plurality of filter devices are commonly connected to the antenna terminal, and at least one of the filter devices is the filter device described above.

[0024] The beneficial effects of the technical solution provided by this application include at least:

[0025] The present application sets a silicon substrate with a horizontal shear wave curvature less than -0.58, sets a piezoelectric layer on the silicon substrate, the Euler angle of the piezoelectric layer is (0±2.5°, β±2.5°, 0±2.5°), where β satisfies 90°≤β≤150°, and sets an interdigital transducer on the piezoelectric layer. In this case, a large-bandwidth elastic wave device capable of suppressing an intrinsic transverse mode is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings:

[0027] Figure 1 Schematic top view and cross-sectional view of a typical elastic wave device 100 based on a piezoelectric composite substrate are shown;

[0028] Figure 2 A schematic diagram of elastic wave propagation is shown;

[0029] Figure 3 A typical admittance / conductance-frequency curve of an elastic wave device 100 based on a piezoelectric composite substrate is shown;

[0030] Figure 4 shows a typical slowness curve diagram of an elastic wave device 100 based on a piezoelectric composite substrate;

[0031] Figure 5 A schematic cross-sectional view of an elastic wave device 200 provided in Embodiment 1 of the present application is shown;

[0032] Figure 6 A schematic diagram showing the definition of silicon crystal axes and the (100), (110), and (111) orientations of silicon;

[0033] Figure 7 shows a slowness curve diagram of a silicon substrate whose main surface is a (100) surface;

[0034] Figure 8 The slowness curve of a silicon substrate whose main surface is (110) surface is shown;

[0035] Fig. 9 The slowness curve of a silicon substrate whose main surface is (111) surface is shown;

[0036] Fig.10 Shows different silicon substrates, different h Al / λ slowness curve of elastic wave device 200;

[0037] Fig.11The elastic wave device 200 of the silicon substrate at (0°, 0°, 45°) is shown with respect to h Al / λ and h LT / λ slowness curve curvature heat map;

[0038] Fig.12 The elastic wave device 200 of the silicon substrate (0°, 0°, 0°) is shown with respect to h Al / λ and h LT / λ slowness curve curvature heat map;

[0039] Fig.13 The elastic wave device 200 of a silicon substrate (135°, 90°, 90°) [plane orientation (110)] with respect to h Al / λ and h LT / λ slowness curve curvature heat map;

[0040] Fig.14 The curvature of the slowness curve of the elastic wave device 200 on the silicon substrate at (0°, 0°, 0°) and the elastic wave device 200 on the silicon substrate at (0°, 0°, 45°) varies with h. Al / λ variation diagram;

[0041] Fig.15 The schematic diagram and admittance / conductance test diagram of the elastic wave device 200 of the silicon substrate (0°, 0°, 45°) actually prepared are shown;

[0042] Fig.16 The schematic diagram and admittance / conductance test diagram of the elastic wave device 200 of the (0°, 0°, 0°) silicon substrate actually prepared are shown;

[0043] Fig.17 A graph showing the curvature of the horizontal shear wave curvature of a silicon substrate with a surface orientation of (100) as a function of ψ is shown;

[0044] Fig.18 A graph showing the curvature of the horizontal shear wave curvature of a silicon substrate with a surface orientation of (110) as a function of ψ is shown;

[0045] Fig.19 A schematic cross-sectional view of an elastic wave device 300 provided in Embodiment 2 of the present application is shown;

[0046] Fig. 20 The elastic wave device 300 of the silicon substrate at (0°, 0°, 45°) is shown with respect to h SiO2 / λ and h LT / λ slowness curve curvature heat map;

[0047] Fig.21 The elastic wave device 300 of the silicon substrate (0°, 0°, 0°) is shown with respect to h SiO2 / λ and hLT / λ slowness curve curvature heat map;

[0048] Fig. 22 The schematic diagram and admittance / conductance test diagram of the elastic wave device 200 of the silicon substrate (0°, 0°, 45°) actually prepared are shown;

[0049] Fig.23 A schematic diagram of an elastic wave device 200 of a silicon substrate (0°, 0°, 0°) actually prepared and a test diagram of admittance / conductance are shown. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0051] Among them, the same parts are represented by the same figure marks. It should be noted that the words "front", "rear", "left", "right", "up" and "down" used in the following description refer to the directions in the drawings of the present application specification, and the words "bottom surface" and "top surface", "inside" and "outside" refer to the direction towards or away from a specific component, respectively. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application specification, the meaning of "multiple" is two or more.

[0052] The present application is further described below in conjunction with the accompanying drawings and embodiments.

[0053] Device Description:

[0054] Figure 1 A schematic top view and a cross-sectional view of a typical piezoelectric composite substrate-based elastic wave device 100 are shown. In recent years, elastic wave devices based on piezoelectric composite substrates of a piezoelectric layer 1 and a non-piezoelectric substrate 3 have attracted wide attention due to their high Q value performance and have been applied to many fields such as radar, communication, and navigation.

[0055] The SAW resonator elastic wave device 100 based on a piezoelectric composite substrate is composed of a piezoelectric layer 1 and a conductive material thin film pattern formed on a piezoelectric composite substrate of a non-piezoelectric substrate 3. The piezoelectric layer 1 is a thin single crystal layer made of a piezoelectric material with a thickness of h. The piezoelectric material is lithium niobate, lithium tantalate, gallium nitride, aluminum nitride or zinc oxide. As is common knowledge, the piezoelectric layer 1 is cut so as to be consistent with the front and back crystal axes of the piezoelectric layer 1, so that the piezoelectric layer 1 has different tangent options. We often use Euler angles to define its tangent, for example, the Euler angle of the piezoelectric layer cut at 42°Y is (0°, 132°, 0°), the Euler angle of the piezoelectric layer cut at Z is (0°, 0°, 0°), the Euler angle of the piezoelectric layer cut at 128°Y is (0°, 38°, 0°), and the Euler angle of the piezoelectric layer cut at 32°Y45°X is (0°, 122°, 45°).

[0056] Admittance is a physical quantity that describes the response of a circuit element to alternating current and voltage, and is usually represented by the symbol Y. For a circuit element, its admittance Y is equal to the ratio of its conductance G to its susceptance B, that is, Y=G+jB, where j is an imaginary unit. In this embodiment, the admittance (dB) can be expressed by the formula Y=20×log 10 |Y| is obtained.

[0057] The admittance ratio is calculated by the formula "admittance ratio = (20 × log 10 |Y1|)-(20×log 10 |Y2|)”, Y1 is the admittance at the resonant frequency of the circuit element, and Y2 is the admittance at the anti-resonant frequency of the circuit element. To a certain extent, the admittance ratio can measure the strength of the resonance of the circuit element.

[0058] The quality factor (Q) is a measure of the energy losses in a resonator. When energy is converted from one form to another, a portion of the energy contained in the system will either escape directly or be repeatedly converted into an irrecoverable energy form.

[0059] Electromechanical coupling coefficient (K 2 ), the resonant frequency of the resonator is set to f s , the anti-resonance frequency is set to f p Under the premise of 2 =π 2 / 4×(f p -f s ) / f p To obtain.

[0060] The non-piezoelectric substrate 3 is a single-layer or multi-layer substrate made of a high-acoustic-velocity material, and is therefore also referred to as a high-acoustic-velocity component. The acoustic velocity of the body wave propagating in the high-acoustic-velocity component is higher than the acoustic velocity of the elastic wave propagating in the piezoelectric layer, thereby increasing the acoustic velocity of the elastic wave in the piezoelectric layer and the frequency of the device. In addition, the high-acoustic-velocity component can effectively seal the elastic wave propagating in the piezoelectric layer in the piezoelectric layer without leakage, thereby increasing the Q value of the device.

[0061] The high acoustic velocity component is made of materials with relatively high acoustic velocity, such as silicon, sapphire, silicon carbide, aluminum nitride, quartz, etc. Table 1 shows the acoustic velocity of longitudinal wave (L), fast shear wave (SH), and slow shear wave (SV) in various materials.

[0062] [Table 1]:

[0063]

[0064] The conductive material film pattern includes the electrode 2a of the interdigital transducer (IDT), the electrode 2b of the reflector, the bus bar 4a of the interdigital transducer and the bus bar 4b of the reflector, and its thickness is h m . The electrode 2a of the interdigital transducer includes a plurality of first electrode fingers and a plurality of second electrode fingers that are interlaced with each other, and a first bus bar and a second bus bar that are opposite to each other in the direction in which the first electrode fingers and the second electrode fingers extend. The distance λ between adjacent first (or second) electrode fingers is usually referred to as the "wavelength" of the IDT. The distance AP where the first and second electrode fingers overlap is usually referred to as the "aperture" of the IDT. The electrode 2b of the reflector includes a plurality of third electrode fingers and a plurality of fourth electrode fingers that are interlaced with each other, and a third bus bar and a fourth bus bar that are opposite to each other in the direction in which the third electrode fingers and the fourth electrode fingers extend.

[0065] The transverse mode is the fluctuation between the resonant frequency and the anti-resonant frequency of the resonator, which is usually caused by the diffraction of elastic waves during propagation. Figure 2 A schematic diagram of elastic wave propagation is shown, wherein the sound wave 11 is a normally propagating sound wave, and the sound wave 10 is a sound wave that undergoes lateral diffraction.

[0066] Figure 3 The figure shows a typical admittance / conductance-frequency curve of an elastic wave device 100 based on a piezoelectric composite substrate. The main excitation mode is a horizontal shear wave. From the curve, it can be seen that a transverse mode appears in the elastic wave device, which is specifically manifested as fluctuations in admittance and conductance between the resonant frequency and the anti-resonant frequency.

[0067] Figure 4The figure shows a typical slowness curve of an elastic wave device 100 based on a piezoelectric composite substrate. In general, the slowness curve can predict the situation in which the elastic wave device generates a transverse mode. When the curvature γ of the slowness curve is greater than 0 (convex), the elastic wave device will generate a transverse mode; when the curvature γ of the slowness curve is less than or equal to 0 (concave), the elastic wave device will not generate a transverse mode. Therefore, it can be seen from the curve in the figure that the curvature γ of the slowness curve of a typical elastic wave device 100 is greater than 0, which will generate a transverse mode.

[0068] Embodiment 1:

[0069] Figure 5 A schematic cross-sectional view of an elastic wave device 200 provided in the first embodiment of the present application is shown. The high acoustic velocity component is a silicon substrate 5 (Silicon, Si), on which a piezoelectric layer 1 is formed, the silicon substrate 5 supports the piezoelectric layer 1, and a conductive material film pattern is formed on the piezoelectric layer 1, the conductive material film pattern includes an electrode 2a of the interdigital transducer, an electrode 2b of the reflector, a bus bar of the interdigital transducer (not shown in the figure) and a bus bar of the reflector (not shown in the figure). The direction parallel to the x-axis in the coordinate system is defined as the electrode finger arrangement direction, which is also the elastic wave propagation direction, the direction parallel to the y-axis in the coordinate system is defined as the electrode finger extension direction (not shown in the figure), and the direction parallel to the z-axis in the coordinate system is defined as the height direction of the elastic wave device 200.

[0070] Specifically, the piezoelectric layer 1 is lithium tantalate (42°YX-LiTaO3) with a 42°Y tangent direction, an Euler angle of (0°, 132°, 0°), and a thickness of h LT ; The wavelength of the elastic wave is λ; The conductive film material pattern is composed of aluminum electrodes with a thickness of h Al .

[0071] Figure 6 The definition of silicon crystal axis and the schematic diagram of silicon (100), (110), (111) orientation are shown. Silicon is a single crystal with a tetragonal structure. Under the premise that the silicon crystal axis is set to (X, Y, Z), due to the symmetry of the crystal structure, the X axis, Y axis and Z axis are equivalent.

[0072] The main surface of the silicon substrate 5 can be a (100) surface, a (110) surface, or a (111) surface. When the main surface of the silicon substrate 5 is a (100) surface, the main surface on the side of the piezoelectric layer 1 in the silicon substrate 5 becomes a (100) surface. The so-called (100) surface is a surface orthogonal to the crystal axis represented by the Miller index

[100] in the crystal structure. In this state, the so-called propagation angle ψ of the elastic wave in the silicon substrate 5 is the angle between the propagation direction of the elastic wave and the crystal orientation

[001] of the Miller index of silicon when viewed from the main surface side of the electrode 2a forming the interdigital transducer of the piezoelectric layer 1. Here, the Euler angle of the silicon substrate 5 is set to (φ, θ, ψ), and ψ in the Euler angle is the above-mentioned propagation angle ψ. When the (100) surface is represented by the Euler angle, it is (0°, 0°, ψ).

[0073] When the main surface of the silicon substrate 5 is a (110) plane, the main surface of the silicon substrate 5 on the side of the piezoelectric layer 1 becomes a (110) plane. In this state, the so-called propagation angle ψ of the silicon substrate 5 is the angle between the propagation direction of the elastic wave and the crystal orientation

[001] of the Miller index of silicon when viewed from the main surface side of the electrode 2a forming the interdigital transducer of the piezoelectric layer 1. When the (110) plane is expressed as an Euler angle, it is (135°, 90°, ψ).

[0074] When the main surface of the silicon substrate is a (111) plane, the main surface of the piezoelectric layer 1 side of the silicon substrate 5 becomes a (111) plane. In this state, the so-called propagation angle ψ of the silicon substrate 5 is the angle between the propagation direction of the elastic wave and the crystal orientation [-1-12] of the Miller index of silicon when viewed from the main surface side of the electrode 2a forming the interdigital transducer of the piezoelectric layer 1. When the (111) plane is expressed as an Euler angle, it is (135°, 54.7°, ψ).

[0075] Figure 7 to Figure 9 The slowness curves of silicon substrates with the main surfaces being (100), (110), and (111) are shown. It can be seen from the curves that the curvature γ of the slowness curves of silicon substrates 5 with different main surfaces and propagation angles ψ is different. Therefore, the main surface and ψ will affect the transverse mode of the elastic wave device 200.

[0076] Fig.10 Shows different silicon substrates, different h Al / λ is a slowness curve of the elastic wave device 200. It can be seen from the curve that when the main surface of the silicon substrate 5 is (100) and the propagation angle ψ is 45°, regardless of h Al / λ, the curvature of the slowness curve of the elastic wave device 200 is greater than 0, and the elastic wave device 200 will generate a transverse mode. At this time, the horizontal shear wave curvature of the silicon substrate 5 is greater than 0 (γ=2.82); when the main surface of the silicon substrate 5 is (100) and the propagation angle ψ is 0°, the control h Al / λ is in the range of 0 to 6%, the curvature of the slowness curve of the elastic wave device 200 is less than or equal to 0, and the elastic wave device 200 does not generate a transverse mode. At this time, the horizontal shear wave curvature of the silicon substrate 5 is less than 0 (γ = -0.94); when the main surface of the silicon substrate 5 is (110) and the propagation angle ψ is 90°, the control h Al When / λ is in the range of 0 to 6%, the curvature of the slowness curve of the elastic wave device 200 is less than or equal to 0, and the elastic wave device 200 will not generate a transverse mode. At this time, the horizontal shear wave curvature of the silicon substrate 5 is less than 0 (γ=-0.58); when the main surface of the silicon substrate 5 is (111) and the propagation angle ψ is 0°, the curvature of the slowness curve of the elastic wave device 200 is greater than 0, and the elastic wave device 200 will generate a transverse mode. At this time, the horizontal shear wave curvature of the silicon substrate 5 is greater than 0 (γ=0.21).

[0077] Therefore, it can be seen from the above results that the curvature of the slowness curve of the elastic wave device 200 is related to the curvature of the slowness curve of the silicon substrate 5. In order to prevent the elastic wave device 200 from generating a transverse mode, the horizontal shear wave curvature of the silicon substrate 5 should be ensured to be less than 0.

[0078] Fig.11 The elastic wave device 200 of the silicon substrate at (0°, 0°, 45°) is shown with respect to h Al / λ and h LT / λ slowness curve curvature heat map. The horizontal axis is h Al / λ, the ordinate is h LT / λ. To ensure that the curvature of the slowness curve is less than 0 and no transverse mode is generated, h Al / λ and h LT / λ must be guaranteed to be outside the dotted line in the upper left corner of the figure.

[0079] Fig.12 The elastic wave device 200 of the silicon substrate (0°, 0°, 0°) is shown with respect to h Al / λ and h LT / λ slowness curve curvature heat map. The horizontal axis is h Al / λ, the ordinate is h LT / λ. To ensure that the curvature of the slowness curve is less than 0 and no transverse mode is generated, h Al / λ and h LT / λ must be guaranteed to be outside the dotted line on the left side of the figure.

[0080] contrast Fig.11 and Fig.12 , (0°, 0°, 0°) The elastic wave device 200 of the silicon substrate does not generate a lateral mode in a larger area. Al / λ and h LT / λ has better selectivity.

[0081] Fig.13 The elastic wave device 200 of a silicon substrate (135°, 90°, 90°) [plane orientation (110)] with respect to h Al / λ and h LT / λ slowness curve curvature heat map. The horizontal axis is h Al / λ, the ordinate is h LT / λ. To ensure that the curvature of the slowness curve is less than 0 and no transverse mode is generated, h Al / λ and h LT / λ must be guaranteed to be outside the dotted line on the left side of the figure.

[0082] To further verify the suppression of the elastic wave device 200 by the two silicon substrates 5, Fig.14 The curvature of the slowness curve of the elastic wave device 200 on the silicon substrate at (0°, 0°, 0°) and the elastic wave device 200 on the silicon substrate at (0°, 0°, 45°) varies with h. Al / λ. From the curve, we can see that no matter h Al Regardless of the value of / λ, the curvature of the slowness curve of the elastic wave device 200 on the silicon substrate 5 (0°, 0°, 0°) is smaller than the curvature of the slowness curve of the elastic wave device 200 on the silicon substrate 5 (0°, 0°, 45°), and the curvature of the slowness curve of the elastic wave device 200 on the silicon substrate 5 (0°, 0°, 0°) is basically kept below 0. Therefore, the former is more conducive to the suppression of the lateral mode.

[0083] Fig.15 The schematic diagram and the admittance / conductance test diagram of the elastic wave device 200 of the silicon substrate (0°, 0°, 45°) actually prepared are shown. Al / λ is 7%, h LT / λ is 0.3. Similar to the above analysis, it can be seen from the test curve that there is a fluctuation between the resonant frequency and the anti-resonant frequency of the elastic wave device 200 on the silicon substrate 5 at (0°, 0°, 45°), indicating that the elastic wave device 200 on the silicon substrate 5 at (0°, 0°, 45°) has a transverse mode.

[0084] Fig.16 The schematic diagram and the admittance / conductance test diagram of the elastic wave device 200 of the (0°, 0°, 0°) silicon substrate actually prepared are shown. Al / λ is 7%, h LT / λ is 0.3. Similar to the above analysis, it can be seen from the test curve that there is no fluctuation between the resonant frequency and the anti-resonant frequency of the elastic wave device 200 on the silicon substrate 5 (0°, 0°, 0°), indicating that the elastic wave device 200 on the silicon substrate 5 (0°, 0°, 0°) does not have a transverse mode.

[0085] Fig.17 and Fig.18The graphs of the horizontal shear wave curvature of the silicon substrate with the plane orientation of (100) and (110) as a function of ψ are shown respectively. The period of the silicon substrate with the plane orientation of (100) is 90°, and the period of the silicon substrate with the plane orientation of (110) is 180°.

[0086] Therefore, for the silicon substrate 5 with a surface orientation of (100), the propagation angle ψ needs to ensure that the horizontal shear wave curvature of the silicon substrate 5 is less than 0, that is, -15°+n×90°≤ψ≤15°+n×90° (n is an integer), and the elastic wave device will not generate a transverse mode; for the silicon substrate 5 with a surface orientation of (110), the propagation angle ψ needs to ensure that the horizontal shear wave curvature of the silicon substrate 5 is less than 0, that is, 80°+n×180°≤ψ≤100°+n×180° (n is an integer), and the elastic wave device will not generate a transverse mode.

[0087] Preferably, for the silicon substrate 5 with a surface orientation of (100), the propagation angle ψ is 0°+n×90° (n is an integer), that is, when the horizontal shear wave curvature of the silicon substrate 5 is -0.94, the elastic wave device 200 achieves the best lateral mode suppression effect; for the silicon substrate 5 with a surface orientation of (110), the propagation angle ψ is 90°+n×180° (n is an integer), that is, when the horizontal shear wave curvature of the silicon substrate 5 is -0.58, the elastic wave device 200 achieves the best lateral mode suppression effect.

[0088] Embodiment 2:

[0089] Fig.19 A schematic cross-sectional view of an elastic wave device 300 provided in the second embodiment of the present application is shown. The high acoustic velocity component is a silicon substrate 5 (Silicon, Si), on which a low acoustic velocity layer 6 is formed, on which a piezoelectric layer 1 is formed, the low acoustic velocity layer 6 supports the piezoelectric layer 1, and on which a conductive material film pattern is formed, the conductive material film pattern includes an electrode 2a of the interdigital transducer, an electrode 2b of the reflector, a bus bar of the interdigital transducer (not shown in the figure), and a bus bar of the reflector (not shown in the figure). The direction parallel to the x-axis in the coordinate system is defined as the electrode finger arrangement direction, which is also the elastic wave propagation direction, the direction parallel to the y-axis in the coordinate system is defined as the electrode finger extension direction (not shown in the figure), and the direction parallel to the z-axis in the coordinate system is defined as the height direction of the elastic wave device 300.

[0090] It is worth mentioning that the difference between the elastic wave device 300 and the elastic wave device 200 is that a low acoustic velocity layer 6 is present between the silicon substrate 5 and the piezoelectric layer 1 .

[0091] Specifically, the piezoelectric layer 1 is lithium tantalate (42°YX-LiTaO3) with a 42°Y tangent direction, an Euler angle of (0°, 132°, 0°), and a thickness of h LT; The low acoustic velocity layer 6 is silicon dioxide with a thickness of h SiO2 ; The wavelength of the elastic wave is λ; The conductive film material pattern is composed of aluminum electrodes with a thickness of h Al .

[0092] Fig. 20 The elastic wave device 300 of the silicon substrate at (0°, 0°, 45°) is shown with respect to h SiO2 / λ and h LT / λ slowness curve curvature heat map. Among them, h Al / λ is 6%, the horizontal axis is h SiO2 / λ, the ordinate is h LT / λ. To ensure that the curvature of the slowness curve is less than 0 and no transverse mode is generated, h SiO2 / λ and h LT / λ must be guaranteed to be located above the dotted line in the figure.

[0093] Fig.21 The elastic wave device 300 of the silicon substrate (0°, 0°, 0°) is shown with respect to h SiO2 / λ and h LT / λ slowness curve curvature heat map. Among them, h Al / λ is 6%, the horizontal axis is h SiO2 / λ, the ordinate is h LT / λ. To ensure that the curvature of the slowness curve is less than 0 and no transverse mode is generated, h SiO2 / λ and h LT / λ must be guaranteed to be located above the dotted line in the figure.

[0094] contrast Fig. 20 and Fig.21 , (0°, 0°, 0°) The elastic wave device 300 of the silicon substrate 5 has a larger area where no transverse mode is generated. SiO2 / λ and h LT / λ has better selectivity.

[0095] Fig. 22 The schematic diagram and the admittance / conductance test diagram of the elastic wave device 200 of the silicon substrate (0°, 0°, 45°) actually prepared are shown. Al / λ is 6%, h LT / λ is 0.27. Similar to the above analysis, it can be seen from the test curve that there is a fluctuation between the resonant frequency and the anti-resonant frequency of the elastic wave device 300 on the silicon substrate 5 at (0°, 0°, 45°), indicating that the elastic wave device 300 on the silicon substrate 5 at (0°, 0°, 45°) has a transverse mode.

[0096] Fig.23 The schematic diagram and the admittance / conductance test diagram of the elastic wave device 200 of the (0°, 0°, 0°) silicon substrate actually prepared are shown.Al / λ is 6%, h LT / λ is 0.27. Similar to the above analysis, it can be seen from the test curve that there is no fluctuation between the resonant frequency and the anti-resonant frequency of the elastic wave device 300 on the silicon substrate 5 at (0°, 0°, 0°), indicating that the elastic wave device 300 on the silicon substrate 5 at (0°, 0°, 0°) does not have a transverse mode.

[0097] Therefore, for the silicon substrate 5 with a surface orientation of (100), the propagation angle ψ needs to ensure that the horizontal shear wave curvature of the silicon substrate 5 is less than 0, that is, -15°+n×90°≤ψ≤15°+n×90° (n is an integer), and the elastic wave device will not generate a transverse mode.

[0098] Preferably, for the silicon substrate 5 with a plane orientation of (100), the propagation angle ψ is 0°+n×90° (n is an integer), that is, when the horizontal shear wave curvature of the silicon substrate 5 is -0.94, the elastic wave device 300 achieves the best lateral mode suppression effect.

[0099] In summary, the present application sets a silicon substrate with a horizontal shear wave curvature less than -0.58, sets a piezoelectric layer on the silicon substrate, the Euler angle of the piezoelectric layer is (0±2.5°, β±2.5°, 0±2.5°), where β satisfies 90°≤β≤150°, and sets an interdigital transducer on the piezoelectric layer. In this case, a large-bandwidth elastic wave device capable of suppressing an intrinsic transverse mode is provided.

[0100] In the embodiments disclosed in the present application, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments disclosed in the present application can be understood according to specific circumstances.

[0101] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. An elastic wave device, characterized in that: include: Silicon substrate, whose horizontal shear wave curvature is less than -0.58; A piezoelectric layer, which is disposed on the silicon substrate, and has an Euler angle of (0±2.5°, β±2.5°, 0±2.5°), wherein β satisfies 90°≤β≤150°; and The interdigital transducer is arranged on the piezoelectric layer.

2. The elastic wave device according to claim 1, wherein: The Euler angle of the silicon substrate is set to (0°, 0°, ψ); Wherein, ψ satisfies -15°+n×90°≤ψ≤15°+n×90°, and n is an integer.

3. The elastic wave device according to claim 1, wherein: The Euler angles of the silicon substrate are set to (135°, 90°, ψ); Wherein, ψ satisfies 80°+n×180°≤ψ≤100°+n×180°, and n is an integer.

4. The elastic wave device according to claim 1, wherein: The speed of sound propagation in the silicon substrate is higher than the speed of sound propagation in the piezoelectric layer.

5. The elastic wave device according to claim 1, wherein: The interdigital transducer is formed by stacking one or more metal material films.

6. The elastic wave device according to claim 1, wherein: A low acoustic velocity layer is further provided between the silicon substrate and the piezoelectric layer.

7. The elastic wave device according to claim 6, characterized in that: The low acoustic velocity layer is composed of one or more combinations of relatively low acoustic velocity materials such as silicon dioxide, glass, silicon oxynitride, tantalum oxide, or silicon dioxide added with a compound mainly composed of fluorine, carbon, or boron.

8. The elastic wave device according to claim 1, wherein: The interdigital transducer also has reflectors on both sides along the propagation direction of the elastic wave.

9. A filter device comprising: a series arm resonator; and a parallel arm resonator, At least one of the series arm resonator and the parallel arm resonator is the elastic wave device according to any one of claims 1 to 8.

10. A multiplexer comprising: an antenna terminal connected to an antenna; and A plurality of filter devices are commonly connected to the antenna terminal, and at least one of the filter devices is the filter device according to claim 9.

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