Temperature compensation type surface acoustic wave device and preparation method and application thereof

Abstract

The application discloses a temperature compensation type surface acoustic wave device and a preparation method and application thereof, and belongs to the technical field of surface acoustic wave devices. The temperature compensation type surface acoustic wave device provided by the application comprises a piezoelectric substrate, an interdigital transducer electrode arranged on the surface of the piezoelectric substrate, and a temperature compensation layer covering the surface of the piezoelectric substrate and / or the interdigital transducer electrode. The temperature compensation layer is an amorphous silicon dioxide film, and the composition of the amorphous silicon dioxide film is expressed as SiO x , wherein 2.1<=x<=2.7. The oxygen-rich component interval defined in the application endows the temperature compensation layer with more excellent temperature compensation capability, and is beneficial to keeping the stability of frequency characteristics within the working temperature range of the device.

Description

Technical Field

[0001] This invention relates to the field of surface acoustic wave (SAW) device technology, and in particular to a temperature-compensated SAW device, its fabrication method, and its application. Background Technology

[0002] Surface acoustic wave (SAW) devices have wide applications in radio frequency filtering, frequency control, and sensing. To improve the temperature stability of these devices, existing technologies often deposit silicon dioxide thin films on the surface of piezoelectric substrates such as lithium niobate and above the electrodes. The temperature compensation structure is constructed by utilizing the difference in thermal and mechanical properties between this thin film and the piezoelectric material.

[0003] Existing solutions for optimizing the temperature compensation performance of silica thin films mainly focus on film thickness, coating method, device structure design, and electrode parameter adjustment, typically treating silica thin films as relatively uniform material layers with fixed properties. However, in actual deposition processes, silica thin films obtained under different deposition conditions often exhibit differences in microstructure and mechanical behavior, which may alter their moderating effect on surface acoustic wave propagation. Current technologies lack systematic research on these differences and their impact on temperature compensation effectiveness. They typically only compensate for the discrepancy between actual device performance and design expectations by adjusting film thickness or device structure, failing to fully explore the inherent potential of thin film materials in temperature compensation applications. Summary of the Invention

[0004] In view of this, the present invention provides a temperature-compensated surface acoustic wave device, its preparation method and application, aiming to improve the temperature compensation effect of the surface acoustic wave device by controlling the composition state of the silicon dioxide thin film.

[0005] In a first aspect, the present invention provides a temperature-compensated surface acoustic wave device, comprising: piezoelectric substrate; Interdigitated transducer electrodes are disposed on the surface of the piezoelectric substrate; A temperature compensation layer covering the surface of the piezoelectric substrate and / or the interdigital transducer electrode; The temperature compensation layer is an amorphous silicon dioxide thin film, and the composition of the amorphous silicon dioxide thin film is represented as SiO₂. x The value of x is in the range of 2.1 ≤ x ≤ 2.7.

[0006] Preferably, the composition of the amorphous silicon dioxide thin film satisfies 2.4 ≤ x ≤ 2.6.

[0007] Preferably, the thickness of the amorphous silicon dioxide film is 0.05λ~0.35λ, where λ is the propagation wavelength of surface acoustic waves.

[0008] Preferably, the piezoelectric substrate is made of lithium niobate single crystal or lithium tantalate single crystal.

[0009] Preferably, the interdigital transducer electrode is made of one or more of aluminum, gold, platinum, and copper, and has a thickness of 50~300 nm.

[0010] Secondly, the present invention provides a method for fabricating the above-mentioned temperature-compensated surface acoustic wave device, comprising the following steps: Provide piezoelectric substrates; Interdigitated transducer electrodes are fabricated on the surface of the piezoelectric substrate; An amorphous silicon dioxide thin film was deposited using reactive magnetron sputtering as a temperature compensation layer, and the composition of the amorphous silicon dioxide thin film was controlled to satisfy 2.1 ≤ x ≤ 2.7.

[0011] Preferably, in the reactive magnetron sputtering process, a silicon target is used as the sputtering source, and reactive magnetron sputtering is performed in a mixed working atmosphere containing inert gas and oxygen.

[0012] Furthermore, the sputtering power of the reactive magnetron sputtering is 1000~1800 W; the reaction gas pressure of the reactive magnetron sputtering is 0.3~0.6 Pa.

[0013] Furthermore, in the reactive magnetron sputtering process, the composition of the amorphous silicon dioxide thin film is controlled to satisfy 2.1 ≤ x ≤ 2.7 by adjusting the oxygen flow rate and / or sputtering power.

[0014] Thirdly, the present invention provides the application of the above-mentioned temperature-compensated surface acoustic wave device or the temperature-compensated surface acoustic wave device prepared by the above-mentioned preparation method in filters or resonators.

[0015] Compared with the prior art, the present invention has achieved the following beneficial effects: This invention limits the composition of the silicon dioxide film in the temperature compensation layer, specifically using amorphous oxygen-rich SiO2 with a composition in the range of 2.1 ≤ x ≤ 2.7. x Thin films. Within this composition range, the local structure, bonding state, and mechanical response behavior of the thin films change significantly compared to stoichiometric silicon dioxide, thus enabling the amorphous network to exhibit greater flexibility and tunability for temperature compensation. These changes improve the thermo-elastic coupling matching between the temperature compensation layer and the piezoelectric substrate, endowing the temperature compensation layer with superior temperature compensation capabilities, thereby enhancing the temperature stability of surface acoustic wave devices. Attached Figure Description

[0016] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. Obviously, those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0017] Figure 1 This is a scanning electron microscope image of the temperature-compensated surface acoustic wave device prepared in Example 5 of the present invention.

[0018] Figure 2 yes Figure 1 Enlarged view of the area within the Chinese border.

[0019] Figure 3 These are the infrared spectra of the amorphous silicon dioxide thin films on the device surfaces of Examples 3 (x≈2.3), 5 (x≈2.5), and Comparative Example 1 (x≈2.0) of the present invention.

[0020] Figure 4 The density and elastic constant (C) of the amorphous silica thin film on the sample surface in Examples 1-7 and Comparative Example 1 of this invention are shown. 11 ) variation pattern diagram; where A is the density variation pattern diagram; B is the elastic constant (C 11 ) Change pattern diagram.

[0021] Figure 5 The normalized frequency offset (Δ) of the devices in Embodiments 3 (x≈2.3), 5 (x≈2.5), 7 (x≈2.7), and Comparative Example 1 (x≈2.0) at different temperatures is shown. f / f ) Data graph; each point in the graph represents measured data, and each straight line represents the result of linear fitting of the measured data; where Δ f This represents the frequency offset of each temperature point relative to the -55℃ reference temperature point. f The frequency value is at room temperature (25℃). Detailed Implementation

[0022] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0023] In this invention, the term "and / or" includes any combination of the listed items and all combinations thereof. Specifically, the phrase "A and / or B" indicates that one of the following three conditions exists: only A (i.e., A exists but B does not exist), only B (i.e., B exists but A does not exist), or both A and B exist simultaneously.

[0024] This invention provides a temperature-compensated surface acoustic wave (SAW) device, its fabrication method, and its application. By controlling the compositional state of the amorphous silicon dioxide thin film in the temperature compensation layer, it offers a new technical approach for the temperature compensation design of SAW devices. In this invention, SiO... x The x value is the atomic ratio of oxygen atoms to silicon atoms in the thin film, as measured by X-ray photoelectron spectroscopy (XPS).

[0025] This invention provides a temperature-compensated surface acoustic wave device, comprising: piezoelectric substrate; Interdigitated transducer electrodes are disposed on the surface of the piezoelectric substrate; A temperature compensation layer covering the surface of the piezoelectric substrate and / or the interdigital transducer electrode; The temperature compensation layer is an amorphous silicon dioxide thin film, and the composition of the thin film is expressed as SiO2. x The value of x is in the range of 2.1 ≤ x ≤ 2.7, preferably 2.4 ≤ x ≤ 2.6.

[0026] In this invention, a piezoelectric substrate is used to excite and propagate surface acoustic waves. The piezoelectric substrate is a piezoelectric single-crystal material, which can be selected as lithium niobate (LiNbO3) single crystal or lithium tantalate (LiTaO3) single crystal. The specific tangent can be selected according to design requirements, for example, a 128° YX-cut lithium niobate single crystal substrate. The thickness, diameter, and other dimensional parameters of the piezoelectric substrate are determined according to the device operating frequency and process requirements, and can be conventionally selected by those skilled in the art.

[0027] In this invention, interdigital transducer electrodes are used to achieve the interconversion between electrical signals and surface acoustic waves. The interdigital transducer electrodes can be made of one or more commonly used metals such as aluminum, gold, platinum, and copper. The thickness of the interdigital transducer electrodes is 50–300 nm, specifically, for example, 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, 250 nm, or 300 nm. The finger width, period, aperture, and other parameters of the electrodes are designed according to the target center frequency and bandwidth, which is conventional technology in this field.

[0028] In this invention, a temperature compensation layer is used to counteract the frequency drift of the piezoelectric substrate caused by temperature changes. In this invention, the temperature compensation layer is an amorphous silicon dioxide thin film, and the composition of this film is expressed as SiO₂. x Here, x represents the atomic ratio of oxygen atoms to silicon atoms, and the value of x ranges from 2.1 ≤ x ≤ 2.7. Within this oxygen-rich composition range, the local structure of the thin film undergoes a detectable change relative to the stoichiometric silicon dioxide (x=2.0), which in turn affects its mechanical response behavior and temperature-dependent characteristics, thus providing additional degrees of freedom for temperature compensation.

[0029] Preferably, the composition of the amorphous silica film satisfies 2.4 ≤ x ≤ 2.6. This invention has found that when x is in the range of 2.4 to 2.6, the density and elastic constant of the film exhibit a characteristic change, which is beneficial for obtaining a more stable temperature compensation effect. Exemplarily, x can be 2.4, 2.5, or 2.6.

[0030] The thickness of the amorphous silica thin film affects the propagation characteristics and temperature compensation effect of surface acoustic waves. Optionally, the film thickness is 0.05λ~0.35λ, where λ is the propagation wavelength of the surface acoustic waves, which is usually determined by the pattern period of the interdigital transducer. The specific thickness can be optimized according to the device design requirements and operating frequency, and can be controlled by adjusting the deposition time in combination with the deposition rate.

[0031] The present invention also provides a method for fabricating the above-mentioned temperature-compensated surface acoustic wave device, comprising the following steps: Provide piezoelectric substrates; Interdigitated transducer electrodes are fabricated on the surface of the piezoelectric substrate; An amorphous silicon dioxide thin film was deposited using reactive magnetron sputtering as a temperature compensation layer, and the composition of the amorphous silicon dioxide thin film was controlled to satisfy 2.1 ≤ x ≤ 2.7.

[0032] The piezoelectric substrate is preferably a lithium niobate or lithium tantalate single-crystal wafer. Before depositing the thin film, the substrate typically needs to be cleaned to remove surface contaminants. For example, the substrate can be cleaned with an RBS cleaning agent, rinsed with deionized water, and dried with high-purity nitrogen. The RBS cleaning agent is a commercially available cleaning agent suitable for removing both organic and inorganic contaminants. To further remove residual adsorbates and improve the adhesion of subsequent electrodes and thin films, the piezoelectric substrate can be treated with oxygen plasma for, for example, 30–120 seconds.

[0033] The steps for fabricating interdigital transducer electrodes on a piezoelectric substrate include: First, spin-coating photoresist onto the piezoelectric substrate surface, followed by pre-baking, exposure, and development to form a predetermined interdigital transducer pattern. Subsequently, an electrode metal layer is deposited using magnetron sputtering or evaporation. The electrode metal layer is made of one or a combination of common metals such as aluminum, gold, platinum, and copper, with a thickness of 50–300 nm. After deposition, the photoresist and the overlying metal layer are removed using a lift-off process to obtain the interdigital transducer electrode structure. After electrode fabrication, low-temperature annealing can be performed to release internal stress and improve the bonding between the interdigital transducer electrode and the piezoelectric substrate. The low-temperature annealing temperature can be 100–300 °C.

[0034] In the reactive magnetron sputtering process described in this invention, a silicon target is used as the sputtering source, and the purity of the silicon target is not less than 99.99%. The sputtering atmosphere consists of a mixture of inert gas and oxygen. Argon is preferred as the inert gas to maintain plasma stability; oxygen is used as the reactive gas to react with the sputtered silicon atoms to generate silicon dioxide.

[0035] In the reactive magnetron sputtering process, the oxygen-silicon ratio of the thin film can be controlled by adjusting the oxygen flow rate and / or sputtering power, thereby achieving SiO2. x The x-value is adjustable within the target range. The x-value is influenced by multiple factors, including oxygen flow rate and sputtering power. Those skilled in the art can determine the combination of process parameters corresponding to the target x-value through conventional experiments. Specifically, increasing the oxygen flow rate and / or decreasing the sputtering power will make the film more oxygen-rich and increase the x-value; conversely, decreasing the oxygen flow rate and / or decreasing the sputtering power will decrease the x-value.

[0036] In this invention, the preferred process parameters for reactive magnetron sputtering are as follows: sputtering power of 1000~1800 W, reaction gas pressure of 0.3~0.6 Pa, and chamber temperature of room temperature to 150℃. These parameters can be combined and adjusted according to the target composition range, deposition rate, film density, and structural stability to achieve controllable preparation of compositionally tunable silica films. After deposition, optional heat treatment can be performed, preferably at a temperature of 150~250℃ for 1~4 hours, to improve film density, release internal stress, and stabilize film properties.

[0037] The present invention also provides the application of the above-described temperature-compensated surface acoustic wave device or the temperature-compensated surface acoustic wave device prepared by the above-described preparation method in filters or resonators.

[0038] Because the temperature compensation layer of this device uses SiO with a specific oxygen-rich composition range. x The thin film exhibits excellent temperature stability because the absolute value of its frequency temperature coefficient can be significantly reduced. This device is particularly suitable for use in resonators within narrowband filters, broadband filters, and high-stability oscillators where high frequency accuracy is required. In practical applications, simply connecting the device to the appropriate circuit in a conventional manner can effectively suppress the drift of signal frequency caused by changes in ambient temperature.

[0039] In summary, the temperature compensation layer in this invention uses amorphous SiO with a composition in the range of 2.1 to 2.7. xThe thin film, within this oxygen-rich composition range, possesses a stable local structure and excellent mechanical response characteristics, effectively reducing the absolute value of the frequency temperature coefficient of surface acoustic wave (SAW) devices and significantly improving their temperature stability. Combined with a selected composition range and reactive magnetron sputtering fabrication process, devices with good consistency and stable compensation effects can be obtained. The fabricated devices are suitable for filters or resonators in communication and sensing fields where high temperature stability is required.

[0040] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0041] Example 1 This embodiment provides a temperature-compensated surface acoustic wave device, including a piezoelectric substrate, interdigitated transducer electrodes disposed on the surface of the piezoelectric substrate, and an amorphous silicon dioxide thin film (SiO2) covering the surfaces of the piezoelectric substrate and the interdigitated transducer electrodes. x The condition x≈2.1 is satisfied.

[0042] (1) Substrate preparation: A 128° YX-cut lithium niobate single crystal was selected as the piezoelectric substrate. The substrate was cleaned with RBS cleaning agent (available commercially), then rinsed with deionized water and dried with high-purity nitrogen. The substrate surface was then subjected to oxygen plasma treatment for 60 seconds.

[0043] (2) Fabrication of interdigital transducer electrodes: Photoresist was spin-coated onto the surface of a piezoelectric substrate, and the predetermined interdigital transducer pattern was formed after pre-baking, exposure, and development. Subsequently, a copper electrode layer was deposited on the surface of the piezoelectric substrate using DC magnetron sputtering at a sputtering power of 1500 W, an argon flow rate of 15 sccm, a working pressure of 0.3 Pa, and a deposition thickness of 200 nm. After deposition, the photoresist and the metal layer above it were removed by a stripping process to obtain the interdigital transducer electrode structure. After electrode fabrication, a low-temperature annealing treatment was performed at 200 °C in a nitrogen atmosphere for 1 hour.

[0044] (3) Temperature compensation layer deposition: Reactive magnetron sputtering was used with a silicon target of ≥99.99% purity as the sputtering source. The cavity was evacuated to 5×10⁻⁶ before sputtering. -5 Below Pa. Argon was introduced as the working gas and oxygen as the reactant gas, and deposition was carried out in a mixed working atmosphere. The argon flow rate was 15 sccm, the oxygen flow rate was 35 sccm, the working gas pressure was controlled at 0.3 Pa, and the sputtering power was 1500 W, resulting in the deposition of an amorphous silicon dioxide thin film. The film thickness was controlled at 0.08λ, where λ = 10 μm, with a thickness of approximately 800 nm.

[0045] (4) Component Characterization: First, X-ray photoelectron spectroscopy (XPS) was used to analyze the composition of the prepared thin film, testing the Si 2p and O 1s peaks, and calculating the O / Si ratio based on the percentage of Si and O atoms in the film to determine the x value. Further, aberration-corrected transmission electron microscopy combined with X-ray energy dispersive spectroscopy (EDS) was used for local characterization of the film. The accelerating voltage was 300 kV, and the energy dispersive spectroscopy acquisition time was 120 seconds. Five points were selected in different regions of the film for component analysis to verify the uniformity of the film's component distribution. The results showed that the XPS and local component analysis were consistent, indicating that the amorphous silica thin film SiO2 prepared in this embodiment... x In the equation, x≈2.1.

[0046] Example 2 The difference between this embodiment and Example 1 is that the flow rate of oxygen as the reaction gas in step (3) is 40 sccm; and the amorphous silicon dioxide thin film SiO2 prepared in this embodiment is measured in step (4). x In the equation, x≈2.2.

[0047] Example 3 The difference between this embodiment and Example 1 is that the flow rate of oxygen as the reactant gas in step (3) is 45 sccm; and the amorphous silicon dioxide thin film SiO2 prepared in this embodiment is measured in step (4). x In the given information, x ≈ 2.3.

[0048] Example 4 The difference between this embodiment and Example 1 is that the flow rate of oxygen as the reaction gas in step (3) is 50 sccm; and the amorphous silicon dioxide thin film SiO2 prepared in this embodiment is measured in step (4). x In the equation, x ≈ 2.4.

[0049] Example 5 Compared with Example 1, the difference in this embodiment is that the flow rate of oxygen as the reaction gas in step (3) is 50 sccm and the sputtering power is 1200 W; and the amorphous silicon dioxide thin film SiO2 prepared in this embodiment is measured in step (4). x In the given information, x ≈ 2.5.

[0050] The scanning electron microscope image of the temperature-compensated surface acoustic wave device prepared in this embodiment is shown below. Figure 1 and Figure 2 As shown, the amorphous silicon dioxide film can be stably covered on the piezoelectric substrate and the interdigital transducer (IDT) electrode surface, and forms a good interfacial bond with the piezoelectric substrate and the IDT electrode.

[0051] Example 6 Compared with Example 1, the difference in this embodiment is that the flow rate of oxygen as the reaction gas in step (3) is 50 sccm and the sputtering power is 1000 W; and the amorphous silicon dioxide thin film SiO2 prepared in this embodiment is measured in step (4). x In the equation, x≈2.6.

[0052] Example 7 Compared with Example 1, the difference in this embodiment is that the flow rate of oxygen as the reaction gas in step (3) is 55 sccm and the sputtering power is 1000 W; and the amorphous silicon dioxide thin film SiO2 prepared in this embodiment is measured in step (4). x In the equation, x≈2.7.

[0053] Comparative Example 1 The difference between this comparative example and Example 1 is that the flow rate of oxygen as the reaction gas in step (3) is 30 sccm; and the amorphous silicon dioxide thin film SiO2 prepared in this comparative example is measured in step (4). x In this case, x ≈ 2.0.

[0054] Test case 1. Infrared spectroscopy characterization Infrared spectroscopy characterization was performed on the amorphous silicon dioxide thin films on the device surfaces of Examples 3 (x≈2.3), 5 (x≈2.5), and Comparative Example 1 (x≈2.0). The results are as follows: Figure 3 As shown, the characteristic absorption peaks of amorphous silica films with different x values ​​vary, indicating that the bonding environment and local structural characteristics inside the film change with the change of composition.

[0055] 2. Analysis of the variation law of density and elastic constant The density and elastic constant variations of the amorphous silica films on the surface of the samples in Examples 1-7 and Comparative Example 1 were analyzed. The film density was measured using the X-ray reflectance method, and the elastic constant C was measured using the Brillouin scattering method. 11 The results are as follows: Figure 4 As shown in Figures A and B, it can be seen that as x increases from 2.0 to 2.7, the film density gradually decreases, and the density change begins to slow down near x≈2.4. Elastic constant C 11 The temperature begins to decrease at x≈2.3 and abruptly changes at x≈2.4, indicating that the mechanical response mechanism of the thin film changes near this component. Comprehensive analysis shows that x≈2.4 is the key node for component regulation in this invention, while 2.4 ≤ x ≤ 2.6 is the preferred component range.

[0056] 3. Comparison of temperature compensation performance The temperature-compensated surface acoustic wave devices prepared in Examples 3, 5, 7, and Comparative Example 1 were placed in a temperature-controlled chamber, and the frequencies of each device were measured at different temperatures. The normalized frequency offset (Δ) was then calculated accordingly. f / f ), where Δ f This represents the frequency offset of each temperature point relative to the -55℃ reference temperature point. f This represents the frequency value at room temperature (25°C). For each device, Δ... f / f A linear fit was performed on the data showing temperature variation, and the slope of the fitted curve is the temperature coefficient of frequency (TCF). The result is as follows: Figure 5 As shown in Table 1.

[0057] Table 1. Normalized frequency offset across the entire temperature range (Δ) f / f and frequency temperature coefficient

[0058] Note: In Table 1, Δ for the entire temperature range f / f This refers to the normalized frequency offset of each device across the entire temperature range of -55℃ to 85℃, calculated from a fitted straight line of the normalized frequency offset, and its value is expressed in ppm; Frequency Temperature Coefficient (TCF) = (ΔF / ΔC) across the entire temperature range f / f ) / 140℃.

[0059] from Figure 5 As can be seen from Table 1, the absolute value of the frequency temperature coefficient of the device using oxygen-rich silica thin film as the temperature compensation layer is significantly lower than that of Comparative Example 1, showing better frequency temperature stability; among them, the temperature-compensated surface acoustic wave device of Example 5 exhibits the best frequency temperature stability.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A temperature-compensated surface acoustic wave device, characterized in that, include: piezoelectric substrate; Interdigitated transducer electrodes are disposed on the surface of the piezoelectric substrate; A temperature compensation layer covering the surface of the piezoelectric substrate and / or the interdigital transducer electrode; The temperature compensation layer is composed of an amorphous silicon dioxide thin film, the composition of which is represented as SiO2. x Where 2.4 ≤ x ≤ 2.6; The thickness of the amorphous silicon dioxide film is 0.05λ~0.35λ, where λ is the propagation wavelength of surface acoustic waves.

2. The temperature-compensated surface acoustic wave device as described in claim 1, characterized in that, The piezoelectric substrate is a single crystal of lithium niobate or a single crystal of lithium tantalate.

3. The temperature-compensated surface acoustic wave device as described in claim 1, characterized in that, The interdigital transducer electrodes are made of one or more of aluminum, gold, platinum, and copper, and have a thickness of 50~300 nm.

4. The method for fabricating a temperature-compensated surface acoustic wave device as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Provide piezoelectric substrates; Interdigitated transducer electrodes are fabricated on the surface of the piezoelectric substrate; An amorphous silicon dioxide thin film was deposited using reactive magnetron sputtering as a temperature compensation layer, and the composition of the amorphous silicon dioxide thin film was controlled to satisfy 2.4 ≤ x ≤ 2.

6.

5. The preparation method according to claim 4, characterized in that, In the reactive magnetron sputtering process, a silicon target is used as the sputtering source, and reactive magnetron sputtering is carried out in a mixed working atmosphere containing inert gas and oxygen.

6. The preparation method according to claim 5, characterized in that, The sputtering power of the reactive magnetron sputtering is 1000~1800 W; the reaction gas pressure of the reactive magnetron sputtering is 0.3~0.6 Pa.

7. The preparation method according to claim 5, characterized in that, In the reactive magnetron sputtering process, the composition of the amorphous silicon dioxide thin film is controlled to satisfy 2.4 ≤ x ≤ 2.6 by adjusting the oxygen flow rate and / or sputtering power.

8. The application of the temperature-compensated surface acoustic wave device as described in any one of claims 1 to 3 or the temperature-compensated surface acoustic wave device prepared by the preparation method described in any one of claims 4 to 7 in filters or resonators.

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