Frequency-tunable surface-acoustic-wave resonator and fabrication method therefor

Abstract

A frequency-tunable surface-acoustic-wave resonator and a fabrication method therefor. The surface-acoustic-wave resonator applies a uniform vertical electric field to a piezoelectric layer by means of an electric-field applying apparatus, wherein the electric field can change the interatomic spacing within crystals of the piezoelectric layer, thereby changing the dielectric constant of the piezoelectric layer, such that the center frequency and resonant frequency of the device, and a bandwidth, can be adjusted along with a change in the applied electric field. Compared with conventional surface-acoustic-wave devices, the operating frequency of the surface-acoustic-wave device can be accurately and rapidly tuned by using an electric field, and the operating frequency of the device can be precisely controlled and measured by means of precisely controlling the vertical electric field, such that a good tuning flexibility is achieved for the device, thereby satisfying requirements of modern communication systems for high data rates and large-capacity communications.

Description

A frequency-tunable surface acoustic wave resonator and its fabrication method Technical Field

[0001] This invention belongs to the field of communication device technology, and particularly relates to a frequency-tunable surface acoustic wave resonator and its fabrication method. Background Technology

[0002] Surface acoustic wave (SAW) devices mainly consist of a piezoelectric substrate and transducer electrodes. The piezoelectric substrate undergoes mechanical deformation under the drive of an electrical signal, which converts the electrical signal into a surface acoustic wave that propagates on the substrate. Piezoelectric materials with good piezoelectric properties are usually selected. The transducer electrodes are used to convert the electrical signal into a surface acoustic wave. They are usually designed with an interdigitated electrode (IDT) structure to excite the propagation of surface acoustic waves through the piezoelectric effect.

[0003] Most surface acoustic wave (SAW) devices on the market are resonator structures with reflective gratings at both ends. The reflective grating structure is used to reflect sound waves on a piezoelectric substrate. This reflection allows the sound waves to propagate back and forth in a fixed area to achieve a resonance effect, which can better reduce response time and insertion loss. It has been widely used in radio frequency systems, 5G communication, Internet of Things (IoT) and other fields.

[0004] With the development of modern communication technology, there is a greater demand for wide bandwidth and frequency flexibility. However, traditional surface acoustic wave resonators have only one specific resonant frequency, which is determined by the specific design of interdigitated electrodes (IDT). This means that the manufactured device can only work within a fixed bandwidth and frequency, which limits its dynamic frequency modulation performance and applicability, and it is no longer suitable for modern communication systems with higher requirements for dynamic response performance. Summary of the Invention

[0005] Therefore, the present invention aims to provide a frequency-tunable surface acoustic wave resonator and its fabrication method. Through the improved resonator structure, the device can change the resonant frequency and bandwidth, thus possessing better frequency flexibility.

[0006] In a first aspect, the present invention provides a frequency-tunable surface acoustic wave resonator, comprising a device substrate and an electric field application device;

[0007] The device substrate includes a piezoelectric layer and a transducer electrode formed on the piezoelectric layer;

[0008] An electric field application device is used to apply a uniform vertical electric field to a piezoelectric layer, and the applied uniform vertical electric field changes the interatomic spacing within the crystal of the piezoelectric layer.

[0009] Furthermore, the electric field applying device applies a uniform vertical electric field in the thickness direction of the piezoelectric layer.

[0010] Furthermore, the electric field application device includes conductive components uniformly formed on the surface of the device substrate.

[0011] Furthermore, the conductive component includes a first conductive layer and a second conductive layer. The first conductive layer is uniformly formed on the transducer electrode, and the second conductive layer is uniformly formed on the surface of the piezoelectric layer that is different from the transducer electrode, such that the piezoelectric layer and the transducer electrode are formed between the first conductive layer and the second conductive layer.

[0012] The first conductive layer is connected to an external voltage source, and the second conductive layer is grounded.

[0013] Furthermore, the material of the conductive component includes at least one of elemental metals, alloys, and graphite, or a composite material including at least one of elemental metals, alloys, and graphite.

[0014] Furthermore, the materials of the first conductive layer and the second conductive layer may be the same or different.

[0015] Furthermore, the tangential direction of the piezoelectric layer is Y-tangential.

[0016] Furthermore, the piezoelectric layer material includes at least one of lithium aluminate, lithium niobate, lithium tantalate, quartz, aluminum nitride, zinc oxide, scandium-doped aluminum nitride, and gallium aluminum arsenide, or a composite layer material including at least one of lithium aluminate, lithium niobate, lithium tantalate, quartz, aluminum nitride, zinc oxide, scandium-doped aluminum nitride, and gallium aluminum arsenide.

[0017] Furthermore, the piezoelectric layer is made of lithium niobate with a 128°﹣Y tangential orientation.

[0018] Furthermore, the device substrate also includes a temperature compensation layer formed on the transducer electrode.

[0019] Furthermore, the device substrate also includes a temperature compensation layer formed between the transducer electrode and the conductive component.

[0020] Furthermore, a temperature compensation layer is formed between the first conductive layer and the transducer electrode.

[0021] Furthermore, the transducer electrode has an interdigitated electrode structure.

[0022] Furthermore, the electrode spacing of the interdigitated electrode structure is half the preset surface acoustic wave wavelength.

[0023] Furthermore, the material of the transducer electrode includes at least one of gold, silver, copper, aluminum, molybdenum, chromium, nickel, platinum, titanium, and tungsten, or an alloy including at least one of gold, silver, copper, aluminum, molybdenum, chromium, nickel, platinum, titanium, and tungsten.

[0024] Furthermore, the device substrate also includes a reflective grating, formed on the piezoelectric layer in the same plane as the transducer electrode.

[0025] Furthermore, the size of the device substrate is within the range of 700μm×40μm, and the size of the transducer electrode is 0.7~5μm.

[0026] Furthermore, the device substrate also includes a substrate on which the piezoelectric layer is formed.

[0027] Furthermore, the substrate material includes at least one of silicon dioxide, sapphire, gallium nitride, silicon carbide, and quartz, or a composite material including at least one of silicon dioxide, sapphire, gallium nitride, silicon carbide, and quartz.

[0028] In a second aspect, the present invention provides a method for fabricating a frequency-tunable surface acoustic wave (SAW) resonator, applied to the frequency-tunable SAW resonator described in the first aspect, comprising:

[0029] A transducer electrode is formed on the surface of the piezoelectric layer to fabricate the device substrate;

[0030] An electric field application device is connected to the device, so that the electric field application device applies a uniform vertical electric field to the piezoelectric layer, and the applied uniform vertical electric field changes the interatomic spacing within the crystal of the piezoelectric layer.

[0031] Furthermore, the electric field application device connected to the device includes:

[0032] An electric field application device is connected in the thickness direction of the piezoelectric layer, so that the electric field application device applies a uniform vertical electric field in the thickness direction of the piezoelectric layer.

[0033] Furthermore, the electric field applying device includes a conductive component, and connecting the electric field applying device to the device includes:

[0034] Conductive components are uniformly deposited on the surface of the device substrate to form conductive components.

[0035] Furthermore, the conductive component includes a first conductive layer and a second conductive layer, and the electric field application device connected to the device includes:

[0036] A first conductive layer is formed by uniformly depositing conductive material on the surface of the transducer electrode, and a second conductive layer is formed by depositing conductive material on the piezoelectric layer on a side different from the transducer electrode, such that the piezoelectric layer and the transducer electrode are formed between the first conductive layer and the second conductive layer.

[0037] The first conductive layer is connected to an external voltage source, and the second conductive layer is grounded.

[0038] Furthermore, forming a transducer electrode on the surface of the piezoelectric layer includes:

[0039] Transducer electrodes are patterned on the piezoelectric layer.

[0040] Furthermore, forming a transducer electrode on the surface of the piezoelectric layer includes:

[0041] A conductive material is deposited on the piezoelectric layer using physical vapor deposition to form an interdigitated electrode structure, which serves as a transducer electrode.

[0042] Furthermore, the above method also includes:

[0043] During the deposition process to form the interdigitated electrode structure, the electrode spacing of the interdigitated electrode structure is controlled to be 1 / 2 of the preset surface acoustic wave wavelength.

[0044] Furthermore, the above method also includes:

[0045] A reflective grating is formed on the piezoelectric layer in the same plane as the transducer electrode.

[0046] Furthermore, the above method also includes:

[0047] A temperature compensation layer is formed on the transducer electrode.

[0048] Furthermore, the above method also includes:

[0049] A temperature compensation layer is deposited between the transducer electrode and the conductive component.

[0050] Furthermore, the above method also includes:

[0051] A substrate is formed on the surface of the piezoelectric layer that is backed by the transducer electrode, so that the piezoelectric layer is formed on the substrate.

[0052] Thirdly, the present invention also provides a surface acoustic wave filter, including the frequency-tunable surface acoustic wave resonator described in the first aspect above.

[0053] Fourthly, the present invention also provides a duplexer, including a transmitting filter and a receiving filter, at least one of which includes the surface acoustic wave filter described in the third aspect above.

[0054] Fifthly, the present invention also provides a surface acoustic wave sensor, including the frequency-tunable surface acoustic wave resonator described in the first aspect above.

[0055] As can be seen from the above technical solution, the present invention has the following beneficial effects:

[0056] The frequency-tunable surface acoustic wave (SAW) resonator provided by this invention applies a uniform vertical electric field to a piezoelectric layer using an electric field application device. This electric field alters the interatomic spacing within the piezoelectric layer, thereby changing its dielectric constant. This allows the device's center frequency, resonant frequency, and bandwidth to be adjusted according to the applied electric field. Compared to traditional SAW devices, this invention enables accurate and rapid tuning of the operating frequency using an electric field. Furthermore, precise control of the vertical electric field allows for precise control and detection of the device's operating frequency, resulting in excellent controllability. This meets the demands of modern communication systems for high data rates and large-capacity communication, while maintaining forward compatibility and supporting higher communication frequencies and data throughput. In further embodiments, the device structure provided by this invention is simplified, requiring no external circuitry, and can be integrated into various communication devices in a compact manner, significantly reducing production costs. Attached Figure Description

[0057] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0058] Figure 1 illustrates a perspective view (left) and a cross-sectional view (right) of the frequency-tunable surface acoustic wave resonator provided in an embodiment of the present invention;

[0059] Figure 2 illustrates the working principle of the frequency-tunable surface acoustic wave resonator provided in the embodiment of the present invention when applying a uniform vertical electric field;

[0060] Figure 3 illustrates the geometry of the frequency-tunable surface acoustic wave resonator provided in an embodiment of the present invention;

[0061] Figure 4 illustrates the curve of the operating frequency of the frequency-tunable surface acoustic wave resonator provided in the embodiment of the present invention as a function of a uniform vertical electric field.

[0062] Figure 5 illustrates the simulation performance of the frequency-tunable surface acoustic wave resonator with silicon dioxide as the temperature compensation layer provided in the embodiment of the present invention.

[0063] Figure 6 illustrates the simulation performance of the frequency-tunable surface acoustic wave resonator with borosilicate as the temperature compensation layer provided in the embodiment of the present invention.

[0064] Figure 7 illustrates the simulation performance of the frequency-tunable surface acoustic wave resonator with zinc oxide as the temperature compensation layer provided in the embodiment of the present invention.

[0065] Figure 8 illustrates a comparison of the coupling coefficient variation rates of frequency-tunable surface acoustic wave resonators provided in the embodiments of the present invention, which use silicon dioxide, (SiO2)borosilicate, and zinc oxide (ZnO) as temperature compensation layers, respectively.

[0066] Figure 9 illustrates a comparison of the resonant frequency response of the frequency-tunable surface acoustic wave resonators provided in the embodiments of the present invention, which use silicon dioxide, (SiO2)borosilicate, and zinc oxide (ZnO) as temperature compensation layers, respectively, to the rate of change of electric field intensity.

[0067] Figure 10 illustrates a comparison of the rate of change of the center frequency response to the electric field intensity of the frequency-tunable surface acoustic wave resonators provided in the embodiments of the present invention, which use silicon dioxide, (SiO2)borosilicate, and zinc oxide (ZnO) as temperature compensation layers, respectively.

[0068] Figure 11 illustrates a flowchart of the fabrication method of the frequency-tunable surface acoustic wave resonator provided in an embodiment of the present invention;

[0069] Figure 12 illustrates the principle of frequency scanning monitoring using the frequency-tunable surface acoustic wave resonator provided in the embodiments of the present invention. Detailed Implementation

[0070] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0071] Modern radio frequency systems, 5G networks, the Internet of Things (IoT), and dynamic frequency applications require devices capable of rapidly adjusting their operating frequencies according to changing conditions, ensuring efficient operation in highly dynamic and fluctuating environments. Surface acoustic wave (SAW) resonators, as a crucial component in communication systems, are ideal filtering and frequency control elements due to their frequency selectivity, tuning capability, and miniaturization characteristics.

[0072] Through observation and research, the inventors of this invention discovered that, due to the piezoelectric effect, when a piezoelectric material crystal is subjected to a certain force from an external electric field, the electric field induces mechanical strain within the material. This strain leads to mechanical stress within the crystal lattice, causing atoms within the crystal to move closer together under the influence of the electric field. When the atoms are squeezed, the stress and the resulting strain cause a change in the resonant frequency of the crystal.

[0073] Based on the above research, the following embodiments of the present invention provide a frequency-tunable surface acoustic wave resonator and its fabrication method, and propose an improved resonator structure that enables the device to change the resonant frequency and bandwidth, thus possessing better frequency flexibility.

[0074] Referring to Figure 1, it illustrates a perspective view and a cross-sectional view of a frequency-tunable surface acoustic wave resonator provided in an embodiment of the present invention, including a device substrate and an electric field application device;

[0075] The device substrate includes a piezoelectric layer 111 and a transducer electrode 112 formed on the piezoelectric layer 111;

[0076] An electric field application device is used to apply a uniform vertical electric field to a piezoelectric layer, and the applied uniform vertical electric field changes the interatomic spacing within the crystal of the piezoelectric layer.

[0077] Figure 2 illustrates the working principle of the surface acoustic wave resonator provided in this embodiment of the invention. Based on the piezoelectric effect, when a piezoelectric material is subjected to an electric field (as shown by the DC source in Figure 2), it will generate mechanical strain, leading to deformation of the material. Under the action of the electric field, the lattice constant of the piezoelectric material changes, that is, the distance between atoms is compressed or stretched with the electric field strength. This structural change leads to a change in the polarization characteristics of the material. The change in interatomic spacing directly affects the polarization response of the material, thereby changing the dielectric constant. After applying an electric field to the surface of the piezoelectric material, the electric field induces mechanical strain, causing the position of atoms in the lattice to adjust, changing the interatomic spacing and distribution. Therefore, the dielectric constant of the material can be continuously or finely adjusted by precisely adjusting the strength of the applied electric field, thereby precisely controlling the operating frequency and bandwidth of the surface acoustic wave device.

[0078] The relationship between the dielectric constant of a piezoelectric layer and the electric field strength can be expressed by the following expression: k eff =k0+αE 2

[0079] Where, k eff α represents the calculated dielectric constant of the piezoelectric layer, k0 represents the initial dielectric constant of the piezoelectric layer material, α represents the magnetic susceptibility of the nonlinear medium, and E represents the electric field strength.

[0080] In this embodiment, the electric field application device applies a uniform vertical electric field in the thickness direction of the piezoelectric layer. Since the electric field acts uniformly on the piezoelectric layer, the change in the dielectric constant of the piezoelectric layer is also uniform.

[0081] In a further embodiment, the electric field application device includes a conductive component uniformly formed on the surface of the device substrate.

[0082] In a specific embodiment, as shown in FIG1, the conductive component includes a first conductive layer 121 and a second conductive layer 122. The first conductive layer 121 is uniformly formed on the transducer electrode 112, and the second conductive layer 122 is uniformly formed on the surface of the piezoelectric layer 111 that is different from the transducer electrode 112, such that the piezoelectric layer 111 and the transducer electrode 112 are formed between the first conductive layer 121 and the second conductive layer 122; wherein the first conductive layer 121 is connected to an external voltage source, and the second conductive layer 122 is grounded.

[0083] When a voltage difference is formed between the upper and lower conductive layers, a uniform electric field in the vertical direction is applied to the piezoelectric layer. By precisely controlling the change in the electric field strength, the operating frequency and bandwidth of the surface acoustic wave device can be precisely adjusted.

[0084] The conductive component is made of at least one of elemental metals, alloys, and graphite, or a composite material comprising at least one of elemental metals, alloys, and graphite. In a further embodiment, when the conductive component is presented as the aforementioned first conductive layer 121 and second conductive layer 122, the materials of the first conductive layer 121 and the second conductive layer 122 may be the same or different. For example, both the first conductive layer 121 and the second conductive layer 122 may be made of elemental gold or elemental silver, or an alloy containing gold or silver; or the first conductive layer 121 may use graphite, and the second conductive layer 122 may use copper.

[0085] In specific implementations, the voltage difference (which can be considered as the applied voltage range) formed by the uniform vertical electric field applied to the piezoelectric layer by the electric field application device is generally between ±1V and ±200V. The specific voltage required depends on the dielectric material, piezoelectric layer, layer thickness, and overall device structure inside the resonator device. This is affected by the dielectric constant, piezoelectric coupling coefficient, electrode geometry, and device layer thickness. For example, low-power resonators fabricated using thin-film piezoelectric layer devices such as zinc oxide or aluminum nitride can operate effectively within a voltage range of ±1V to ±50V; high-performance resonators fabricated using bulk (thicker) piezoelectric materials such as lithium niobate, or other thicker thin-film devices may require a voltage application of ±50V to ±200V.

[0086] In a further embodiment, the tangential direction of the piezoelectric layer is Y-shaped, and the material of the piezoelectric layer includes at least one of lithium aluminate, lithium niobate, lithium tantalate, quartz, aluminum nitride, zinc oxide, scandium-doped aluminum nitride, and gallium aluminum arsenide, or a composite layer material including at least one of lithium aluminate, lithium niobate, lithium tantalate, quartz, aluminum nitride, zinc oxide, scandium-doped aluminum nitride, and gallium aluminum arsenide.

[0087] In a more preferred embodiment, the piezoelectric layer is made of lithium niobate with a 128°﹣Y tangential orientation.

[0088] In a further embodiment, the device substrate also includes a temperature compensation layer formed on the transducer electrode, and in a more specific embodiment, the temperature compensation layer is formed between the transducer electrode and the conductive component.

[0089] The function of the temperature compensation layer is to reduce or compensate for the frequency drift of the resonator caused by temperature changes, thereby improving the frequency stability of the resonator.

[0090] The temperature compensation layer can be made of at least one of silicon dioxide (SiO2), aluminum, molybdenum, niobium, tungsten, titanium, magnesium, etc., or a composite material including at least one of the above-mentioned silicon dioxide (SiO2), aluminum, molybdenum, niobium, tungsten, titanium, magnesium, etc. Specifically, a material with opposite thermal expansion characteristics can be selected as the temperature compensation layer according to the thermal expansion characteristics of the piezoelectric layer.

[0091] Taking the device structure shown in Figure 1 as an example, the device substrate includes a temperature compensation layer 113, which is formed between the first conductive layer 121 and the transducer electrode 112.

[0092] In a further embodiment, the transducer electrode is an interdigitated electrode structure. In a specific design, the electrode spacing of the interdigitated electrode structure can be set to 1 / 2 of the preset surface acoustic wave wavelength.

[0093] The transducer electrode is made of at least one of gold, silver, copper, aluminum, molybdenum, chromium, nickel, platinum, titanium, and tungsten, or an alloy of at least one of gold, silver, copper, aluminum, molybdenum, chromium, nickel, platinum, titanium, and tungsten.

[0094] In a further embodiment, the device substrate also includes a reflective grating formed on the piezoelectric layer in the same plane as the transducer electrode.

[0095] In another embodiment of the present invention, to improve the mechanical stability and process feasibility of the device, the device substrate may further include a substrate on which the piezoelectric layer is formed to enhance mechanical strength, increase the durability and reliability of the device. Some substrate materials with higher thermal stability, such as quartz and silicon, can also improve the overall thermal stability of the device. When the piezoelectric layer needs to be fabricated into a piezoelectric thin film, the substrate can also more easily utilize microfabrication processes such as MEMS to help process the piezoelectric material into a thin layer, making it easier to mass-produce.

[0096] The substrate material includes at least one of silicon dioxide, sapphire, gallium nitride, silicon carbide, and quartz, or a composite material including at least one of silicon dioxide, sapphire, gallium nitride, silicon carbide, and quartz.

[0097] In one embodiment of the present invention, due to the simplified improved device structure, no complex peripheral circuitry is required, and therefore the overall resonator device structure is compact and can be fabricated into a small-sized part for integration into other devices.

[0098] Taking the device geometry diagram shown in Figure 3 as an example, the device substrate includes a lithium niobate piezoelectric layer 311, a pair of interdigitated electrodes 312 and a temperature compensation layer 313 made of silicon dioxide in the order of formation. Metal conductive layers 320 are formed on the upper and lower surfaces (not shown) of the device substrate. The overall size of the surface acoustic wave resonator can be controlled within the range of 700μm×40μm. The size of the interdigitated electrodes is 0.7~5μm, and the electrode spacing of the interdigitated electrode structure is 1 / 2 of the preset surface acoustic wave wavelength λ.

[0099] Figure 4 illustrates the relationship between the externally applied uniform vertical electric field and the frequency change generated by the surface acoustic wave resonator, demonstrating that the device can respond linearly to changes in the electric field, thereby achieving precise tuning.

[0100] Figures 5-7 illustrate the simulated performance of resonant devices using silicon dioxide (SiO2), borosilicate, and zinc oxide (ZnO) as temperature compensation layers, respectively. In Figures 5-7, the horizontal axis represents the resonant frequency, and the vertical axis represents the admittance. The different curves in each figure represent different applied uniform vertical electric field intensities. As shown in Figures 5-7, the resonant devices with different temperature compensation layers can all respond linearly to the uniform vertical electric field applied to the piezoelectric layer, and the curves are smooth between the resonant and anti-resonant points.

[0101] Figure 8 shows a comparison of the coupling coefficient variation rate of resonant devices with silicon dioxide (SiO2), borosilicate, and zinc oxide (ZnO) as temperature compensation layers. Figures 9 and 10 show the resonant frequency and center frequency of the resonant devices with the above three temperature compensation layers in response to the change of electric field strength. In Figures 8-10, the horizontal axis represents the electric field strength, and the vertical axis represents the variation rate.

[0102] Based on the above-described frequency-tunable surface acoustic wave resonator, the following embodiments of the present invention also provide a method for fabricating a frequency-tunable surface acoustic wave resonator.

[0103] Figure 11 illustrates a flowchart of a method for fabricating a frequency-tunable surface acoustic wave resonator according to an embodiment of the present invention, including the following steps:

[0104] Step S1110. Form a transducer electrode on the surface of the piezoelectric layer to prepare the device substrate.

[0105] Step S1120. Connect an electric field application device to the device so that the electric field application device applies a uniform vertical electric field to the piezoelectric layer, and the applied uniform vertical electric field changes the interatomic spacing within the crystal of the piezoelectric layer.

[0106] In a further embodiment, step S1120 includes:

[0107] An electric field application device is connected in the thickness direction of the piezoelectric layer, so that the electric field application device applies a uniform vertical electric field in the thickness direction of the piezoelectric layer.

[0108] Specifically, when the electric field applying device includes a conductive component, the conductive component can be uniformly deposited on the surface of the device substrate.

[0109] In a more specific embodiment, the conductive component includes a first conductive layer and a second conductive layer, and step S1120 includes the following steps:

[0110] A first conductive layer is formed by uniformly depositing conductive material on the surface of the transducer electrode, and a second conductive layer is formed by depositing conductive material on the piezoelectric layer on a side different from the transducer electrode, such that the piezoelectric layer and the transducer electrode are formed between the first conductive layer and the second conductive layer.

[0111] The first conductive layer is connected to an external positive voltage source, and the second conductive layer is grounded.

[0112] In a further embodiment, step S1110 includes the following steps:

[0113] Transducer electrodes are patterned on the piezoelectric layer.

[0114] In a more specific embodiment, step S1110 includes the following steps:

[0115] A conductive material is deposited on the piezoelectric layer using physical vapor deposition to form an interdigitated electrode structure, which serves as a transducer electrode.

[0116] In a more specific embodiment, during the deposition of the interdigitated electrode structure, the electrode spacing of the interdigitated electrode structure is controlled to be 1 / 2 of the preset surface acoustic wave wavelength, and the electrode size is controlled to be between 0.7 and 5 μm.

[0117] In a more specific embodiment, photolithography is used to pattern the interdigitated electrode structure on the surface of the piezoelectric layer, and physical vapor deposition is used to deposit conductive material as the interdigitated electrode.

[0118] In a further embodiment, the above method further includes:

[0119] A reflective grating is formed on the piezoelectric layer in the same plane as the transducer electrode.

[0120] In a further embodiment, the above method further includes:

[0121] A temperature compensation layer is formed on the transducer electrode.

[0122] In a further embodiment, the above method further includes:

[0123] A temperature compensation layer is deposited between the transducer electrode and the conductive component.

[0124] In a further embodiment, the above method further includes:

[0125] A substrate is formed on the surface of the piezoelectric layer that is backed by the transducer electrode, so that the piezoelectric layer is formed on the substrate.

[0126] As shown in Figure 12, according to the above embodiments of the present invention, since the device frequency can respond linearly to changes in the electric field, an external frequency scanning monitor can be connected to the device to continuously scan the frequency of the resonator and obtain its S-parameters. The S-parameters change linearly in response to the voltage difference between the conductive components. Through the correlation formula, the electric field strength applied to the device can be accurately calculated based on the changes in the S-parameters. This allows the surface acoustic wave device provided by the embodiments of the present invention to be used not only as a filter but also as a sensor.

[0127] Another embodiment of the present invention relates to a surface acoustic wave filter, including the surface acoustic wave resonator provided in the foregoing embodiments.

[0128] Another embodiment of the present invention provides a duplexer including a transmitting filter and a receiving filter, at least one of which includes the surface acoustic wave filter provided in the foregoing embodiments.

[0129] Embodiments of the present invention also provide a surface acoustic wave sensor, including the surface acoustic wave resonator provided in the foregoing embodiments.

[0130] Those skilled in the art will understand that the structures shown in the figures are merely block diagrams of some structures related to the present application and do not constitute a limitation on the terminal device to which the present application is applied. Specific terminal devices may include more or fewer components than those shown in the figures, or combine certain components, or have different component arrangements.

[0131] In the description of this specification, the use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "possible design," etc., refers to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0132] When using expressions such as "at least one of A, B, and C", they should generally be interpreted in accordance with the meaning that is commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B, and C, etc.).

[0133] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0134] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A frequency-tunable surface acoustic wave resonator, characterized in that, Includes the device substrate and the electric field application device; The device substrate includes a piezoelectric layer and a transducer electrode formed on the piezoelectric layer; The electric field applying device is used to apply a uniform vertical electric field to the piezoelectric layer, and the applied uniform vertical electric field changes the interatomic spacing within the crystal of the piezoelectric layer.

2. The surface acoustic wave resonator according to claim 1, characterized in that, The electric field applying device applies a uniform vertical electric field in the thickness direction of the piezoelectric layer.

3. The surface acoustic wave resonator according to claim 1, characterized in that, The electric field application device includes conductive components uniformly formed on the surface of the device substrate.

4. The surface acoustic wave resonator according to claim 3, characterized in that, The conductive component includes a first conductive layer and a second conductive layer. The first conductive layer is uniformly formed on the transducer electrode, and the second conductive layer is uniformly formed on the surface of the piezoelectric layer that is different from the transducer electrode, such that the piezoelectric layer and the transducer electrode are formed between the first conductive layer and the second conductive layer. The first conductive layer is connected to an external voltage source, and the second conductive layer is grounded.

5. The surface acoustic wave resonator according to claim 1, characterized in that, The transducer electrode has an interdigitated electrode structure.

6. The surface acoustic wave resonator according to claim 5, characterized in that, The electrode spacing of the interdigitated electrode structure is 1 / 2 of the preset surface acoustic wave wavelength.

7. A method for fabricating a frequency-tunable surface acoustic wave resonator, characterized in that, The surface acoustic wave resonator, which is frequency-tunable as described in any one of claims 1 to 6, comprises: A transducer electrode is formed on the surface of the piezoelectric layer to fabricate the device substrate; An electric field application device is connected to the device substrate, so that the electric field application device applies a uniform vertical electric field to the piezoelectric layer, and the applied uniform vertical electric field changes the interatomic spacing within the crystal of the piezoelectric layer.

8. The method according to claim 7, characterized in that, The electric field application device applied to the device substrate includes: An electric field applying device is connected in the thickness direction of the piezoelectric layer, so that the electric field applying device applies a uniform vertical electric field in the thickness direction of the piezoelectric layer.

9. The method according to claim 7, characterized in that, The electric field applying device includes a conductive component, and the connection of the electric field applying device on the device substrate includes: Conductive components are uniformly deposited on the surface of the device substrate to form conductive components.

10. The method according to claim 9, characterized in that, The conductive component includes a first conductive layer and a second conductive layer, and the electric field application device connected to the device substrate includes: A first conductive layer is formed by uniformly depositing a conductive material on the surface of the transducer electrode, and a second conductive layer is formed by depositing a conductive material on the piezoelectric layer on a surface different from the transducer electrode, such that the piezoelectric layer and the transducer electrode are formed between the first conductive layer and the second conductive layer. The first conductive layer is connected to an external voltage source, and the second conductive layer is grounded.

11. The method according to claim 7, characterized in that, The formation of the transducer electrode on the surface of the piezoelectric layer includes: A conductive material is deposited on the piezoelectric layer using physical vapor deposition to form an interdigitated electrode structure, which serves as a transducer electrode.

12. The method according to claim 11, characterized in that, The method further includes: During the deposition process to form the interdigitated electrode structure, the electrode spacing of the interdigitated electrode structure is controlled to be 1 / 2 of the preset surface acoustic wave wavelength.

13. A surface acoustic wave filter, characterized in that, Includes the frequency-tunable surface acoustic wave resonator as described in any one of claims 1 to 6.

14. A duplexer, comprising a transmitting filter and a receiving filter, characterized in that, At least one of the transmitting filter and the receiving filter includes the surface acoustic wave filter as described in claim 13.

15. A surface acoustic wave sensor, characterized in that, Includes the frequency-tunable surface acoustic wave resonator as described in any one of claims 1 to 6.

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