CN118337167A - Elastic wave device - Google Patents

Abstract

The application relates to an elastic wave device, and relates to the technical field of elastic waves. According to 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 piezoelectric layer is formed above the sapphire substrate, at least the IDT electrode and the reflector electrode are formed on the piezoelectric layer, the reflector electrodes are positioned on two sides of the IDT electrode along the propagation direction of elastic waves, and when the Euler angle of the sapphire substrate is in a specific range, high-order clutter caused by a composite multilayer structure based on the piezoelectric film can be restrained, and the preparation difficulty and the preparation cost of the device can be reduced.

Description

Elastic wave device

Technical Field

The present application relates to the field of elastic wave technology, and in particular to an elastic wave device capable of suppressing high-order clutter.

Background technique

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.

Mobile communication systems are developing from 3G and 4G to 5G. The 5G communication era places increasingly stringent requirements on the performance of surface acoustic wave filters, such as high frequency, high power, large bandwidth, and low loss. Traditional surface acoustic wave devices are subject to the limitations of the piezoelectric material itself, and the acoustic waves will inevitably leak toward the substrate, resulting in low Q value and coupling coefficient, which cannot fully meet the high performance requirements of mobile communications devices. The surface acoustic wave device based on the composite multilayer structure of lithium tantalate/lithium niobate piezoelectric film can effectively confine the acoustic energy inside the piezoelectric film, greatly improving the performance of the device. The composite multilayer structure has attracted much attention due to its advantages of low insertion loss, low temperature drift, large bandwidth, and high power.

However, the composite multilayer structure based on piezoelectric film will also cause many parasitic noise problems, such as high-order parasitic noise response, which will deteriorate the out-of-band suppression level of the filter and cause signal crosstalk between duplexers or RF modules, greatly affecting the performance of the communication device.

Patent Document 1 provides an elastic wave device capable of suppressing high-order modes.

Patent document 1: CN116601871A

However, in the elastic wave device disclosed in Patent Document 1, the substrate is specified to be silicon, and the patent does not impose any corresponding restrictions on the Euler angles of the substrate.

The composite multilayer structure has four layers and is relatively complex, which undoubtedly increases the difficulty and cost of preparing the device.

Summary of the invention

The purpose of the present application is to provide an elastic wave device to solve the problems existing in the above-mentioned prior art.

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

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

The sapphire substrate whose main surface is the a-plane has an Euler angle of (90°±2.5°, 90°±2.5°, ψ±2.5°);

A piezoelectric layer is disposed on the sapphire substrate, and under the premise that the wavelength of the elastic wave is set to λ, the thickness of the piezoelectric layer is 0.3λ;

An IDT electrode disposed on the piezoelectric layer; and

Reflector electrodes, which are arranged on the piezoelectric layer and are located on both sides of the IDT electrode along the propagation direction of the elastic wave;

Wherein, the ψ in the Euler angle of the sapphire substrate is 30°≤ψ≤95° or 210°≤ψ≤275°.

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

The sapphire substrate has a c-plane as the main surface, and its Euler angle is (0°±2.5°, 0°±2.5°, ψ±2.5°);

A piezoelectric layer is disposed on the sapphire substrate, and under the premise that the wavelength of the elastic wave is set to λ, the thickness of the piezoelectric layer is 0.3λ;

An IDT electrode disposed on the piezoelectric layer; and

Reflector electrodes, which are arranged on the piezoelectric layer and are located on both sides of the IDT electrode along the propagation direction of the elastic wave;

Among them, the ψ in the Euler angle of the sapphire substrate is 20°≤ψ≤28° or 40°≤ψ≤80° or 92°≤ψ≤100° or 140°≤ψ≤148° or 160°≤ψ≤200° or 212°≤ψ≤220° or 260°≤ψ≤268° or 280°≤ψ≤320° or 332°≤ψ≤340°.

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

The sapphire substrate with the main surface being the m-plane has an Euler angle of (0°±2.5°, 90°±2.5°, ψ±2.5°);

A piezoelectric layer is disposed on the sapphire substrate, and under the premise that the wavelength of the elastic wave is set to λ, the thickness of the piezoelectric layer is 0.3λ;

An IDT electrode disposed on the piezoelectric layer; and

Reflector electrodes, which are arranged on the piezoelectric layer and are located on both sides of the IDT electrode along the propagation direction of the elastic wave;

Among them, ψ in the Euler angle of the sapphire substrate is 60°≤ψ≤70° or 80°≤ψ≤95° or 100°≤ψ≤120° or 240°≤ψ≤260° or 265°≤ψ≤280° or 290°≤ψ≤300°.

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

The sapphire substrate with the main surface being the r-plane has an Euler angle of (0°±2.5°, 123.23°±2.5°, ψ±2.5°);

A piezoelectric layer is disposed on the sapphire substrate, and under the premise that the wavelength of the elastic wave is set to λ, the thickness of the piezoelectric layer is 0.3λ;

An IDT electrode disposed on the piezoelectric layer; and

Reflector electrodes, which are arranged on the piezoelectric layer and are located on both sides of the IDT electrode along the propagation direction of the elastic wave;

Among them, the ψ in the Euler angle of the sapphire substrate is 0°≤ψ≤20° or 32°≤ψ≤38° or 108°≤ψ≤112° or 158°≤ψ≤170° or 190°≤ψ≤202° or 248°≤ψ≤252° or 322°≤ψ≤328° or 340°≤ψ≤360°.

In a fifth aspect, the present application provides a filter or a 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 described in any one of the above items.

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

A sapphire substrate whose main surface is an a-plane, c-plane, m-plane or r-plane is used as a supporting substrate, a piezoelectric layer is formed on the top, and at least an IDT electrode and a reflector electrode are formed on the piezoelectric layer. The reflector electrodes are located on both sides of the IDT electrode along the propagation direction of the elastic wave. When the Euler angle of the sapphire substrate is within a specific range, high-order noise caused by a composite multilayer structure based on the piezoelectric film can be suppressed, thereby reducing the difficulty and cost of device preparation.

BRIEF DESCRIPTION OF THE DRAWINGS

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:

FIG1 shows a schematic top view and a cross-sectional view of a typical surface acoustic wave (SAW) resonator 100 based on a piezoelectric composite substrate;

FIG. 2 shows a typical admittance/conductance-frequency graph of a surface acoustic wave (SAW) resonator 100 based on a piezoelectric composite substrate;

FIG3 shows a phase-frequency graph of a typical surface acoustic wave (SAW) resonator 100 based on a piezoelectric composite substrate;

FIG4 shows the definition of sapphire crystal axes and a schematic diagram of sapphire's a-plane, m-plane, c-plane and r-plane;

FIG5 shows a cross-sectional view of an elastic wave device 200 provided in Comparative Example 1 of the present application;

FIG6 shows a graph of the admittance/conductance-frequency of the elastic wave device 200 provided in Comparative Example 1 of the present application;

FIG. 7 shows a vibration mode diagram of the main mode 30 of the elastic wave device 200 provided in Comparative Example 1 of the present application;

FIG8 shows a vibration mode diagram of the clutter 31 of the elastic wave device 200 provided in Comparative Example 1 of the present application;

FIG. 9 shows a vibration mode diagram of the clutter 32 of the elastic wave device 200 provided in Comparative Example 1 of the present application;

FIG. 10 shows a phase-frequency curve diagram of the elastic wave device 200 provided in Comparative Example 1 of the present application;

FIG. 11 is a graph showing a change in the electromechanical coupling coefficient of the elastic wave device 200 provided in Comparative Example 1 of the present application as a function of the thickness h _LN of the piezoelectric layer;

FIG12 is a graph showing a variation curve of the minimum phase of the clutter response of the elastic wave device provided in the first embodiment of the present application as ψ varies;

FIG13 shows a curve diagram showing the maximum phase of the spurious response of the elastic wave device provided in the second embodiment of the present application as a function of ψ;

FIG14 shows a curve diagram showing the maximum phase of the spurious response of the elastic wave device provided in the third embodiment of the present application as a function of ψ;

FIG15 shows a curve diagram showing the maximum phase of the spurious response of the elastic wave device provided in the fourth embodiment of the present application as a function of ψ;

FIG16 shows a curve diagram showing the maximum phase of the spurious response of the elastic wave device provided in the fifth embodiment of the present application as a function of ψ;

FIG17 shows a curve diagram showing the maximum phase of the spurious response of the elastic wave device provided in Example 6 of the present application as a function of ψ;

FIG18 shows a curve diagram showing the maximum phase of the spurious response of the elastic wave device provided in Comparative Example 2 of the present application as a function of ψ;

FIG19 shows a graph showing the variation of the minimum phase 19 of the high-order clutter response of an elastic wave device with a piezoelectric layer thickness h _LN of 0.1λ to 0.4λ as ψ varies;

FIG20 shows an admittance/conductance-frequency curve of an elastic wave device according to an embodiment to achieve a high-order clutter response suppression effect;

FIG21 is a phase-frequency graph showing the effect of suppressing high-order clutter response achieved by the elastic wave device according to the embodiment;

FIG. 22 shows a cross-sectional view of an elastic wave device 300 provided in the first variation of the present application.

Detailed ways

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.

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.

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

Device Description:

Fig. 1 shows a schematic top view and a cross-sectional view of a typical piezoelectric composite substrate-based surface acoustic wave (SAW) resonator 100. In recent years, SAW resonators based on piezoelectric composite substrates of a piezoelectric layer 1 and a non-piezoelectric substrate 3 have attracted widespread attention due to their high Q value, large electromechanical coupling coefficient, good heat dissipation and other properties, and have been applied to many fields such as radar, communication, and navigation.

The SAW resonator based on the 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 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 relative to each other, 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 15°Y is (0°, 105°, 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°).

Admittance:

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 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 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.

The high acoustic velocity component is made of a material with a relatively high acoustic velocity, such as silicon, sapphire, silicon carbide, aluminum nitride, etc. Table 1 shows the acoustic velocities of three different modes of elastic waves in various materials.

Table 1:

2 shows a typical admittance/conductance-frequency curve of a surface acoustic wave (SAW) resonator 100 based on a piezoelectric composite substrate. From the curve, it can be seen that the resonator has a resonant frequency of 1911 MHz, an anti-resonant frequency of 2004 MHz, and an electromechanical coupling coefficient of 11.5%, and the high frequency region 60 has basically no spurious response.

Electromechanical coupling coefficient:

Assuming that the resonant frequency of the resonator is f _s and the anti-resonant frequency is f _p , the electromechanical coupling coefficient can be obtained by the formula K ² =π ² /4×(f _p -f _s )/f _p .

The quantitative measurement of the resonator's spurious response is usually reflected by the phase-frequency curve of the resonator. FIG3 shows a phase-frequency curve of a typical surface acoustic wave (SAW) resonator 100 based on a piezoelectric composite substrate. The phase of the high-order region 70 of the resonator is basically maintained at about 90°. When a spurious response occurs, the phase of the high-order region 70 of the resonator will suddenly change, and the amplitude of the mutation represents the intensity of the spurious response. Generally speaking, the larger the amplitude of the mutation, the stronger the spurious response; conversely, the weaker the spurious response.

At present, the surface acoustic wave (SAW) of piezoelectric composite substrates is mostly based on Si materials, such as LT/ _SiO2 /AlN/Si structure. However, in this structure, silicon is a semiconductor material, which will form parasitic conductivity at the interface, resulting in large RF loss. In addition, its structure is relatively complex, leading to problems such as cumbersome process and high cost. Compared with Si, sapphire has extremely high resistivity and is an insulator. At the same time, it has a low dielectric constant, which can reduce electrical loss. Therefore, sapphire can be used as a high-acoustic-velocity substrate to directly composite with piezoelectric materials to achieve the preparation of high-performance surface acoustic wave (SAW) devices with simple process and low cost.

The commercial sapphire substrate widely used at present has four crystal planes: a-plane, m-plane, c-plane and r-plane. Due to the anisotropy of the crystal material, the performance of sapphire with different crystal planes combined with the piezoelectric layer will be different. Figure 4 shows the definition of sapphire crystal axis and the schematic diagram of sapphire's a-plane, m-plane, c-plane and r-plane.

In this embodiment, the non-piezoelectric substrate 3 is a sapphire substrate. Sapphire is a single crystal with a hexagonal structure. When the crystal axes of sapphire are set to (α ₁ , α ₂ , α ₃ , C), the α ₁ axis, α ₂ axis and α ₃ axis are equivalent due to the symmetry of the crystal structure.

The main surface of the sapphire substrate can be an a-plane, an m-plane, a c-plane or an r-plane. When the main surface of the sapphire substrate is an a-plane, the main surface on the side of the piezoelectric layer 1 in the sapphire substrate becomes a (11-20) plane. The so-called (11-20) plane is a plane orthogonal to the crystal axis represented by the Miller index [11-20] in the crystal structure. In this state, the so-called propagation angle ψ of the elastic wave in the sapphire substrate, as shown in Figure 1, is the 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 main surface side of the piezoelectric layer 1 where the IDT electrode 2a is formed. Here, the Euler angle of the sapphire substrate is set to In addition, ψ in the Euler angle is the above-mentioned propagation angle ψ. When the (11-20) plane is expressed by the Euler angle, it is (90°, 90°, ψ).

When the main surface of the sapphire substrate is the c-plane, the main surface of the piezoelectric layer 1 side of the sapphire substrate becomes the (0001) plane. In this state, the so-called propagation angle ψ of the sapphire substrate is the 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 main surface side of the piezoelectric layer 1 where the IDT electrode 2a is formed, as shown in FIG1. When the (0001) plane is expressed as the Euler angle, it is (0°, 0°, ψ).

When the main surface of the sapphire substrate is an m-plane, the main surface of the sapphire substrate on the side of the piezoelectric layer 1 becomes a (1-100) plane. In this state, the so-called propagation angle ψ of the sapphire substrate is the 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 main surface side of the piezoelectric layer 1 where the IDT electrode 2a is formed, as shown in FIG1. When the (1-100) plane is expressed as an Euler angle, it is (0°, 90°, ψ).

When the main surface of the sapphire substrate is the r-plane, the main surface of the piezoelectric layer 1 side of the sapphire substrate becomes the (1-102) plane. In this state, the so-called propagation angle ψ of the sapphire substrate is the 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 main surface side of the piezoelectric layer 1 where the IDT electrode 2a is formed, as shown in FIG1. When the (1-102) plane is expressed as the Euler angle, it is (0°, 122.23°, ψ).

As shown in FIG1 , the conductive material film pattern includes an IDT (interdigital transducer) electrode 2a, a reflector electrode 2b, an IDT bus bar 4a and a reflector bus bar 4b, and the thickness is h _m . The IDT electrode 2a includes a plurality of first electrode fingers and a plurality of second electrode fingers interlaced with each other, and a first bus bar and a second bus bar facing each other in the extending direction of the first electrode fingers and the second electrode fingers. 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 reflector electrode 2b includes a plurality of third electrode fingers and a plurality of fourth electrode fingers interlaced with each other, and a third bus bar and a fourth bus bar facing each other in the extending direction of the third electrode fingers and the fourth electrode fingers.

Comparative Example 1:

FIG5 shows a cross-sectional view of the elastic wave device 200 provided in the first comparative example of the present application. The high acoustic velocity component 5 is a sapphire substrate of the a-plane, c-plane, m-plane or r-plane, on which a piezoelectric layer 1 is formed and supports the piezoelectric layer 1, and a conductive material film pattern is formed on the piezoelectric layer 1, and the conductive material film pattern includes an IDT electrode 2a, a reflector electrode 2b, an IDT bus bar (not shown in the figure) and a reflector bus bar (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.

FIG6 shows the admittance/conductance-frequency curve of the elastic wave device 200 provided in the comparative example 1 of the present application. As can be seen from the figure, the main mode 30 of the elastic wave device 200 has a resonant frequency of 1899 MHz and an anti-resonant frequency of 2199 MHz, and the electromechanical coupling coefficient is 33.7%. The clutter 31 has a resonant frequency of 2817 MHz, and the clutter 32 has a resonant frequency of 2919 MHz. The clutter 31 and 32 are far away from the main mode and appear in the high-frequency region of the resonator, which seriously damages the performance of the elastic wave device 200.

FIG7 shows a vibration modal diagram of the main mode 30 of the elastic wave device 200 provided in Comparative Example 1 of the present application. It can be seen from the modal diagram that this is a typical horizontal shear (SH) wave mode. In addition, FIG8 and FIG9 also show vibration modal diagrams of clutter 31 and 32, respectively, and these high-order clutter are SH high-order modes, Lamb waves, etc.

FIG10 shows a phase-frequency curve of the elastic wave device 200 provided in Example 1 of the present application. It can be seen from the figure that the phase of the high-order region 80 of the typical elastic wave device 200 has a maximum mutation of -73°, and the change amplitude reaches 163°, which shows that the typical elastic wave device 200 has a very strong stray response in the high-order region 80, which seriously damages its performance. -73° is defined as the minimum phase of the stray response of the high-order region 80 of the resonator, so as to analyze the change in the strength of the stray response.

FIG11 shows a graph of the electromechanical coupling coefficient of the elastic wave device 200 provided in the comparative example 1 of the present application as a function of the thickness of the piezoelectric layer h _LN . The sapphire substrates are selected from sapphires of the a-plane, c-plane, m-plane and r-plane, respectively, ψ is 0°, and the wavelength of the elastic wave is λ. As can be seen from the figure, when h _LN ≤0.3λ, the electromechanical coupling coefficient of the elastic wave device 200 increases as h _LN increases, and when h _LN ＞0.3λ, the electromechanical coupling coefficient of the elastic wave device 200 remains stable and is maintained at about 34%.

Embodiment 1:

The elastic wave device provided in the first embodiment has a substantially similar structure to the elastic wave device 200 provided in the first comparative example, except that:

The piezoelectric layer 1 is lithium niobate, the Euler angle is (0°, β, 0°), and the thickness is h _LN ;

The conductive film material pattern is composed of aluminum electrodes with a thickness h _m of 8%λ;

The wavelength of the elastic wave is λ;

The high-acoustic-velocity member 5 is made of a sapphire substrate whose main surface is an a-plane and whose Euler angles are (90°, 90°, ψ).

Figure 12 shows a curve chart showing the variation of the minimum phase of the spurious response of the elastic wave device provided in Example 1 of the present application with the change of ψ. In detail, h _LN is 0.3λ and β is 105°. When the minimum phase is greater than 30°, the high-order 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 curve chart, when 30°≤ψ≤95° or 210°≤ψ≤275°, the minimum phase of the spurious response of the elastic wave device is greater than 30°, and the spurious response is weak.

Embodiment 2:

The elastic wave device provided in the second embodiment has a substantially similar structure to the elastic wave device 200 provided in the first comparative example, except that:

The piezoelectric layer 1 is lithium niobate, the Euler angle is (0°, β, 0°), and the thickness is h _LN ;

The conductive film material pattern is composed of aluminum electrodes with a thickness h _m of 8%λ;

The wavelength of the elastic wave is λ;

The high-acoustic-velocity member 5 is made of a sapphire substrate whose main surface is a c-plane and whose Euler angles are (0°, 0°, ψ).

Figure 13 shows a curve chart showing the variation of the maximum phase of the spurious response of the elastic wave device provided in Example 2 of the present application with the change of ψ. In detail, h _LN is 0.3λ and β is 105°. When the minimum phase is greater than 30°, the high-order 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 curve chart, when 20°≤ψ≤28° or 40°≤ψ≤80° or 92°≤ψ≤100° or 140°≤ψ≤148° or 160°≤ψ≤200° or 212°≤ψ≤220° or 260°≤ψ≤268° or 280°≤ψ≤320° or 332°≤ψ≤340°, the minimum phase of the spurious response of the elastic wave device is greater than 30°, and the spurious response is weak.

Embodiment three:

The elastic wave device provided in the third embodiment has a substantially similar structure to the elastic wave device 200 provided in the first comparative example, except that:

The piezoelectric layer 1 is lithium niobate, the Euler angle is (0°, β, 0°), and the thickness is h _LN ;

The conductive film material pattern is composed of aluminum electrodes with a thickness h _m of 8%λ;

The wavelength of the elastic wave is λ;

The high-acoustic-velocity member 5 is made of a sapphire substrate whose main surface is an m-plane, and the Euler angles are (0°, 90°, ψ).

Figure 14 shows a curve chart showing the variation of the maximum phase of the spurious response of the elastic wave device provided in Example 3 of the present application with the change of ψ. In detail, h _LN is 0.3λ and β is 105°. When the minimum phase is greater than 30°, the high-order clutter response of the elastic wave device is at an acceptable level, and the performance of the resonator is not greatly affected. According to the curve chart, when 60°≤ψ≤70° or 80°≤ψ≤95° or 100°≤ψ≤120° or 240°≤ψ≤260° or 265°≤ψ≤280° or 290°≤ψ≤300°, the minimum phase of the spurious response of the elastic wave device is greater than 30°, and the clutter response is weak.

Embodiment 4:

The elastic wave device provided in the fourth embodiment has a substantially similar structure to the elastic wave device 200 provided in the first comparative example, except that:

The piezoelectric layer 1 is lithium niobate, the Euler angle is (0°, β, 0°), and the thickness is h _LN ;

The conductive film material pattern is composed of aluminum electrodes with a thickness h _m of 8%λ;

The wavelength of the elastic wave is λ;

The high-acoustic-velocity component 5 is made of a sapphire substrate whose main surface is an r-plane, and the Euler angle is (0°, 122.23°, ψ).

Figure 15 shows a curve chart showing the variation of the maximum phase of the spurious response of the elastic wave device provided in Example 4 of the present application with the change of ψ. In detail, h _LN is 0.3λ and β is 105°. When the minimum phase is greater than 30°, the high-order 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 curve chart, when 0°≤ψ≤20° or 32°≤ψ≤38° or 108°≤ψ≤112° or 158°≤ψ≤170° or 190°≤ψ≤202° or 248°≤ψ≤252° or 322°≤ψ≤328° or 340°≤ψ≤360°, the minimum phase of the spurious response of the elastic wave device is greater than 30°, and the spurious response is weak.

Embodiment five:

The elastic wave device provided in the fifth embodiment has a substantially similar structure to the elastic wave device 200 provided in the first comparative example, except that:

The piezoelectric layer 1 is lithium niobate, the Euler angle is (0°, β, 0°), and the thickness is h _LN ;

The conductive film material pattern is composed of aluminum electrodes with a thickness h _m of 8%λ;

The wavelength of the elastic wave is λ;

The high-acoustic-velocity member 5 is made of a sapphire substrate whose main surface is a c-plane and whose Euler angles are (0°, 0°, ψ).

Figure 16 shows a curve chart showing the variation of the maximum phase of the spurious response of the elastic wave device provided in Example 5 of the present application with the change of ψ. In detail, h _LN is 0.3λ and β is 122°. When the minimum phase is greater than 30°, the high-order 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 curve chart, when 0°≤ψ≤8° or 112°≤ψ≤128° or 232°≤ψ≤248° or 352°≤ψ≤360°, the minimum phase of the spurious response of the elastic wave device is greater than 30°, and the spurious response is weak.

Embodiment six:

The elastic wave device provided in the sixth embodiment has a substantially similar structure to the elastic wave device 200 provided in the first comparative example, except that:

The piezoelectric layer 1 is lithium niobate, the Euler angle is (0°, β, 0°), and the thickness is h _LN ;

The conductive film material pattern is composed of aluminum electrodes with a thickness h _m of 8%λ;

The wavelength of the elastic wave is λ;

The high-acoustic-velocity member 5 is made of a sapphire substrate whose main surface is a c-plane and whose Euler angles are (0°, 0°, ψ).

Figure 17 shows a curve chart showing the variation of the maximum phase of the spurious response of the elastic wave device provided in Example 6 of the present application with the change of ψ. In detail, h _LN is 0.3λ and β is 90°. When the minimum phase is greater than 30°, the high-order 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 curve chart, when 18°≤ψ≤102° or 138°≤ψ≤222° or 258°≤ψ≤342°, the minimum phase of the spurious response of the elastic wave device is greater than 30°, and the spurious response is weak.

It is worth noting that by comparing the second embodiment, the fifth embodiment and the sixth embodiment, it can be found that, under the same other conditions, the smaller β is, the larger the range of ψ for high-order clutter suppression becomes. Therefore, the high-order clutter suppression of LN with different Euler angles β achieved by the present application through different face sapphires is also within the scope of this protection.

Comparative Example 2:

The elastic wave device provided in the second comparative example has a substantially similar structure to the elastic wave device 200 provided in the first comparative example, except that:

The piezoelectric layer 1 is lithium niobate, the Euler angle is (0°, β, 0°), and the thickness is h _LN ;

The conductive film material pattern is composed of aluminum electrodes with a thickness h _m of 8%λ;

The wavelength of the elastic wave is λ;

The high-acoustic-velocity member 5 is made of a sapphire substrate whose main surface is an m-plane, and the Euler angles are (0°, 90°, ψ).

Figure 18 shows a graph showing the variation of the maximum phase of the spurious response of the elastic wave device provided in Example 2 of the present application with the change of ψ. In detail, h _LN is 0.3λ and β is 122°. When the minimum phase is greater than 30°, the high-order clutter 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, there is no 0°≤ψ≤360° that satisfies the minimum phase of the spurious response of the elastic wave device greater than 30°. Therefore, the elastic wave device provided in Example 2 cannot suppress high-order clutter responses.

The above embodiments are all based on the piezoelectric layer thickness h _LN being 0.3λ. However, it should be noted that the change in the thickness of the piezoelectric layer also affects the appropriate angle range of ψ. Figure 19 shows a curve of the minimum phase 19 of the high-order stray wave response of an elastic wave device with a piezoelectric layer thickness h _LN of 0.1λ to 0.4λ as ψ changes. Among them, the sapphire substrate uses c-plane sapphire. It can be seen from the figure that the elastic wave devices with different piezoelectric layer thicknesses have different sensitivities to the change of ψ in the stray response. As h _LN increases, the appropriate range of ψ gradually shrinks.

Therefore, for elastic wave devices, as the thickness of the piezoelectric layer increases, the suitable range of ψ for high-order clutter response suppression by sapphire will also be reduced. In other words, the thinner the piezoelectric layer, the more conducive it is to the suppression of high-order clutter response by ψ. The high-order clutter suppression achieved by this patent through sapphires of different thicknesses LN on different faces is also within the scope of this protection.

FIG20 shows an admittance/conductance-frequency curve of an elastic wave device according to an embodiment to achieve a high-order clutter response suppression effect. Among them, the sapphire substrate uses r-plane sapphire, and the thickness h _LN of the piezoelectric layer is 0.3λ. It can be seen from the figure that the main mode 30 of the elastic wave device has a resonant frequency of 1980MHz and an anti-resonant frequency of 2283MHz, and the electromechanical coupling coefficient is 32.7%. It should be noted that the clutter in the high-frequency region 90 is basically suppressed. FIG21 shows a phase-frequency curve of an elastic wave device according to an embodiment to achieve a high-order clutter response suppression effect. Similar to the previous analysis, for a sapphire substrate with an r-plane and ψ of 0°, the minimum phase of the high-order region 80 of the elastic wave device is 50°, which is much larger than the acceptable phase level of 30°, and the high-order clutter response of the elastic wave device is well suppressed.

Modification 1:

FIG22 shows a cross-sectional view of an elastic wave device 300 provided in the first variant of the present application. The high acoustic velocity component 5 is a sapphire substrate of the a-plane, c-plane, m-plane or r-plane, on which a low acoustic velocity material layer 5 is formed, and the piezoelectric layer 1 is supported. A conductive material film pattern is formed on the piezoelectric layer 1, and the conductive material film pattern includes an IDT electrode 2a, a reflector electrode 2b, an IDT bus bar (not shown in the figure) and a reflector bus bar (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.

In detail, the piezoelectric layer 1 is lithium niobate, the Euler angle is (0°, β, 0°), and the thickness is h _LN ;

The conductive film material pattern is composed of aluminum electrodes with a thickness h _m of 8%λ;

The low acoustic velocity material layer 6 is silicon dioxide.

The structural difference from the elastic wave device provided in the above embodiment is that a low acoustic velocity material layer is present between the sapphire substrate and the piezoelectric layer.

The sound velocity of the body wave propagating in the low-acoustic-velocity material layer is lower than the sound velocity of the body wave propagating in the piezoelectric layer. It is usually composed of silicon dioxide, glass, silicon oxynitride, tantalum oxide, or a material with fluorine, carbon, or boron compounds added to silicon dioxide as the main component. It can improve the frequency-temperature drift coefficient of the elastic wave device.

Based on the same reasons as those of the first, second, third, fourth, fifth or sixth embodiment, the structure of this variation can exhibit good high-order clutter suppression function.

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.

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 (9)

1. An elastic wave device, comprising: The sapphire substrate whose main surface is the a-plane has an Euler angle of (90°±2.5°, 90°±2.5°, ψ±2.5°); A piezoelectric layer is disposed on the sapphire substrate, and under the premise that the wavelength of the elastic wave is set to λ, the thickness of the piezoelectric layer is 0.3λ; An IDT electrode disposed on the piezoelectric layer; and Reflector electrodes, which are arranged on the piezoelectric layer and are located on both sides of the IDT electrode along the propagation direction of the elastic wave; Wherein, the ψ in the Euler angle of the sapphire substrate is 30°≤ψ≤95° or 210°≤ψ≤275°. 2. An elastic wave device, comprising: The sapphire substrate has a c-plane as the main surface, and its Euler angle is (0°±2.5°, 0°±2.5°, ψ±2.5°); A piezoelectric layer is disposed on the sapphire substrate, and under the premise that the wavelength of the elastic wave is set to λ, the thickness of the piezoelectric layer is 0.3λ; An IDT electrode disposed on the piezoelectric layer; and Reflector electrodes, which are arranged on the piezoelectric layer and are located on both sides of the IDT electrode along the propagation direction of the elastic wave; Among them, the ψ in the Euler angle of the sapphire substrate is 20°≤ψ≤28° or 40°≤ψ≤80° or 92°≤ψ≤100° or 140°≤ψ≤148° or 160°≤ψ≤200° or 212°≤ψ≤220° or 260°≤ψ≤268° or 280°≤ψ≤320° or 332°≤ψ≤340°. 3. An elastic wave device, comprising: The main surface of the sapphire substrate is the m-plane, and its Euler angle is (0°±2.5°, 90°±2.5°, ψ±2.5°); A piezoelectric layer is disposed on the sapphire substrate, and under the premise that the wavelength of the elastic wave is set to λ, the thickness of the piezoelectric layer is 0.3λ; An IDT electrode disposed on the piezoelectric layer; and Reflector electrodes, which are arranged on the piezoelectric layer and are located on both sides of the IDT electrode along the propagation direction of the elastic wave; Among them, ψ in the Euler angle of the sapphire substrate is 60°≤ψ≤70° or 80°≤ψ≤95° or 100°≤ψ≤120° or 240°≤ψ≤260° or 265°≤ψ≤280° or 290°≤ψ≤300°. 4. An elastic wave device, comprising: The sapphire substrate with the main surface being the r-plane has an Euler angle of (0°±2.5°, 123.23°±2.5°, ψ±2.5°); A piezoelectric layer is disposed on the sapphire substrate, and under the premise that the wavelength of the elastic wave is set to λ, the thickness of the piezoelectric layer is 0.3λ; An IDT electrode disposed on the piezoelectric layer; and Reflector electrodes, which are arranged on the piezoelectric layer and are located on both sides of the IDT electrode along the propagation direction of the elastic wave; Among them, the ψ in the Euler angle of the sapphire substrate is 0°≤ψ≤20° or 32°≤ψ≤38° or 108°≤ψ≤112° or 158°≤ψ≤170° or 190°≤ψ≤202° or 248°≤ψ≤252° or 322°≤ψ≤328° or 340°≤ψ≤360°. 5. The elastic wave device according to any one of claims 1 to 4, characterized in that: The piezoelectric layer is lithium niobate, and the Euler angle is (0°, 105°, 0°). 6. The elastic wave device according to any one of claims 1 to 4, characterized in that: The elastic wave device further includes a low acoustic velocity material layer, and the low acoustic velocity material layer is provided between the sapphire substrate and the piezoelectric layer. 7. The elastic wave device according to claim 6, characterized in that: The acoustic velocity of the body wave propagating in the low acoustic velocity material layer is lower than the acoustic velocity of the body wave propagating in the piezoelectric layer; The acoustic velocity of the bulk wave propagating in the sapphire substrate is higher than the acoustic velocity of the bulk wave propagating in the piezoelectric layer. 8. The elastic wave device according to any one of claims 1 to 4, characterized in that: The IDT electrode is formed by stacking one or more metal material films. 9. 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 8.