Automatic temperature control bulk acoustic wave resonator, filter and preparation method

Abstract

The invention provides a self-temperature-control bulk acoustic wave resonator, a filter and a preparation method, and relates to the technical field of bulk acoustic wave resonators. Comprising a substrate, a supporting layer, a bottom electrode, a piezoelectric layer and a top electrode which are stacked in sequence, a cavity is formed between the substrate and the supporting layer, a light starting layer and a light refrigeration layer are stacked on the top electrode in sequence, and the light starting layer is used for absorbing heat generated by the resonator and exciting low-energy fluorescence when the heat reaches the critical temperature; the light refrigeration layer can convert high-energy photons under the driving of low-energy fluorescence; and the light starting layer and the light refrigeration layer are matched for converting heat energy into light energy for consumption. The self-temperature-control bulk acoustic wave resonator solves the problems that in the prior art, control over heat of the resonator is not ideal, the temperature rises too fast under high frequency, and the resonator is prone to failure, the heat of a device is stably controlled under high frequency and high power capacity, and the reliability of the resonator is improved. And the power capacity of the bulk acoustic wave resonator and the filter is greatly improved while the long-term stable operation of the device is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of bulk acoustic wave resonators, and in particular, to a self-temperature-controlled bulk acoustic wave resonator, a filter and a preparation method thereof. Background Art

[0002] With the development of artificial intelligence technology, higher requirements are put forward for communication technology. For example, there is an urgent need for communication means with low latency and high information volume. This has greatly promoted the development of high-frequency communication technology with fast transmission speed and large data bandwidth. Among them, radio frequency filters are one of the core components in the high-frequency communication field, and their operating frequency mainly depends on the operating frequency band of the resonator. Therefore, the development of high-frequency bulk acoustic wave resonators is of great significance for the development of high-frequency communication technology.

[0003] However, defects in the piezoelectric thin film lead to acoustic wave loss, resulting in a large amount of heat generation, which may cause the resonant frequency of the device to drift and even cause the structure to burn out and fail. Moreover, as the operating frequency increases, the increase in the acoustic wave frequency promotes the increase in the heating phenomenon of the resonator, which results in the device showing a low power capacity at high frequencies. Therefore, developing a technology for temperature control and heat control to improve the power capacity of the bulk acoustic wave resonator is the core to achieve stable application of the device at high frequencies.

[0004] The current mainstream methods focus on improving the heat conduction efficiency of the device, such as by changing the device structure, introducing a heat conduction layer, etc. However, this method is not ideal for heat control of the resonator, and the temperature rises too fast at high frequencies, making it easy to fail.

[0005] In view of the above problems, there is currently no effective technical solution. Summary of the Invention

[0006] The purpose of the present invention is to provide a self-temperature-controlled bulk acoustic wave resonator, a filter and a preparation method thereof, which solve the problems of the existing technology that the heat control of the resonator is not ideal, the temperature rises too fast at high frequencies, and it is easy to fail, and achieve the effect of stably controlling the heat of the device at high frequencies and high power capacities, which is beneficial to ensuring the long-term stable operation of the device while greatly improving the power capacities of the bulk acoustic wave resonator and the filter.

[0007] In a first aspect, the present invention provides a self-temperature-controlled bulk acoustic wave resonator, including a substrate, a support layer, a bottom electrode, a piezoelectric layer and a top electrode stacked in sequence. A cavity is provided between the substrate and the support layer. A light activation layer and a photo-refrigeration layer are stacked in sequence on the top electrode. The light activation layer is used to absorb the heat generated by the resonator and emit low-energy fluorescence when reaching the critical temperature. The photo-refrigeration layer can convert into high-energy photons under the drive of the low-energy fluorescence. The light activation layer and the photo-refrigeration layer cooperate to convert thermal energy into light energy for consumption.

[0008] The self - temperature - controlled bulk acoustic wave resonator provided by the present invention realizes automatic temperature control based on a photo - initiation layer and a photo - refrigeration layer, greatly improving the power capacity of the bulk acoustic wave resonator and the filter, and effectively solving the problem of device failure caused by severe heating of the bulk acoustic wave resonator and the filter at high frequencies and high powers, which is beneficial to ensuring the long - term stable operation of the device.

[0009] Further, the photo - initiation layer is made of a thermoluminescent material.

[0010] Using a thermoluminescent material as the photo - initiation layer can realize the automatic temperature control of the resonator, improving the power capacity and stability of the device under high - frequency operation.

[0011] Further, the thermoluminescent material is any one of halides, sulfates, sulfides, binary oxides or ternary oxides that emit light when heated.

[0012] The limitation of the material type is beneficial for more easily finding thermoluminescent materials that meet the performance requirements in practical applications and simplifying the material screening and preparation process.

[0013] Further, the photo - refrigeration layer is made of a photoluminescent material.

[0014] Further, the photoluminescent material is halide perovskite or ytterbium - doped fluoride.

[0015] By selecting a suitable photoluminescent material, the energy conversion efficiency can be optimized, thereby improving the refrigeration effect of the photo - refrigeration layer.

[0016] Further, both the bottom electrode and the top electrode are made of any one or more of the materials Au, Ag, Ru, W, Mo, Ir, Al, Pt, Nb, Hf.

[0017] Further, the piezoelectric layer is made of any one of AlN, , , in the above - mentioned materials.

[0018] Further, the substrate is made of any one of Si, sapphire, SiC; the support layer is made of , any one or more of the materials SiC.

[0019] In a second aspect, the present invention provides a filter, including the above - mentioned self - temperature - controlled bulk acoustic wave resonator.

[0020] In a third aspect, the present invention provides a preparation method for preparing the above - mentioned self - temperature - controlled bulk acoustic wave resonator, including the following steps: S1. After making a groove on the upper surface of the substrate, grow a sacrificial layer on the groove; S2. Sequentially fabricate a support layer, a bottom electrode, a piezoelectric layer, and a top electrode covering the groove on the upper surface of the substrate; S3. Spin-coat a light-initiating layer on the top electrode; S4. After the light-initiating layer is dried, spin-coat a light-cooling layer on the light-initiating layer; S5. Release the sacrificial layer to form a cavity between the substrate and the support layer, thereby fabricating the self-controlled temperature bulk acoustic wave resonator.

[0021] As can be seen from the above, the self-controlled temperature bulk acoustic wave resonator provided by the present invention utilizes a thermoluminescent material to excite low-energy fluorescence to drive the light-cooling layer to convert into high-energy photons, thereby quickly consuming the heat of the resonator. When the heat is lower than the critical temperature of the luminescent material, it no longer emits light to drive the light-cooling layer to work, achieving the purpose of automatically adjusting the temperature of the resonator, realizing the long-term stable operation of the device at high frequency and high power capacity, and greatly improving the stability and power capacity of the device.

[0022] Other features and advantages of the present invention will be described in the subsequent specification, and, in part, will be obvious from the specification, or can be understood by implementing the embodiments of the present invention. The objectives and other advantages of the present invention can be realized and obtained by the structures specifically pointed out in the written specification and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 FIG. is a schematic structural diagram of a self-controlled temperature bulk acoustic wave resonator provided by an embodiment of the present invention.

[0024] Figure 2 FIG. is a flowchart of the preparation of a self-controlled temperature bulk acoustic wave resonator provided by an embodiment of the present invention.

[0025] Figure 3 FIG. is a flowchart of a preparation method provided by an embodiment of the present invention.

[0026] Reference Numerals: 100, substrate; 200, support layer; 300, bottom electrode; 400, piezoelectric layer; 500, top electrode; 600, cavity; 700, light-initiating layer; 800, light-cooling layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The following describes in detail the embodiments of the present invention. Examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0028] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and defined, the terms "mounted", "connected" and "coupled" shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection, an electrical connection or a connection capable of mutual communication; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention may be understood according to specific circumstances.

[0030] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0031] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use of other materials.

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0033] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined. At the same time, in the description of the present invention, the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0034] Referring to the attached Figure 1 , the present invention provides a self-controlled temperature bulk acoustic wave resonator, which includes a substrate 100, a support layer 200, a bottom electrode 300, a piezoelectric layer 400, and a top electrode 500 stacked in sequence. A cavity 600 is provided between the substrate 100 and the support layer 200. A light activation layer 700 and a light cooling layer 800 are stacked in sequence on the top electrode 500. The light activation layer 700 is used to absorb the heat generated by the resonator and emit low-energy fluorescence when reaching the critical temperature; the light cooling layer 800 can convert into high-energy photons under the drive of the low-energy fluorescence; the light activation layer 700 and the light cooling layer 800 cooperate to convert thermal energy into light energy for consumption.

[0035] Regarding the structure of a bulk acoustic wave resonator, the substrate serves as the support structure of the device, and the support layer is fabricated on top of the substrate to further support the functional thin film layer above. A cavity is provided between the substrate and the support layer to achieve acoustic isolation and energy concentration of the bulk acoustic wave resonator. The bottom electrode, piezoelectric layer, and top electrode are sequentially fabricated on the support layer to form the core structure of the bulk acoustic wave resonator. Among them, the piezoelectric layer is the key functional layer for realizing the conversion between electrical signals and acoustic signals, and the bottom electrode and top electrode are used to apply the driving voltage. The optical activation layer and the optical refrigeration layer are fabricated on the top electrode to form a stacked structure for regulating the temperature of the resonator. A possible implementation of the optical activation layer is made of a thermoluminescent material, which can spontaneously emit fluorescence when the temperature reaches a certain critical value after absorbing heat. Thermoluminescent materials can include halides, sulfates, sulfides, binary oxides, and ternary oxides that emit light when heated. A possible implementation of the optical refrigeration layer is made of a photoluminescent material, which can emit higher-energy photons after absorbing light with a specific wavelength to achieve the optical refrigeration effect. Photoluminescent materials can include halide perovskites, ytterbium-doped fluorides, etc. The bottom electrode and the top electrode can be made of any one or more of the materials such as gold, silver, ruthenium, tungsten, molybdenum, iridium, aluminum, platinum, niobium, and hafnium to meet the requirements of conductivity and process compatibility. The piezoelectric layer can be made of any one of the materials such as aluminum nitride, , , to achieve excellent piezoelectric properties. The substrate can be made of any one of the materials such as silicon, sapphire, and silicon carbide, and the support layer can be made of any one or more of the materials such as silicon nitride and silicon carbide to meet the requirements of mechanical strength and process.

[0036] Specifically, when the bulk acoustic wave resonator operates, acoustic wave loss occurs due to piezoelectric thin film defects, generating heat. When the generated heat is absorbed by the optical activation layer on the top electrode and the resonator temperature rises to the critical temperature of the optical activation layer, the optical activation layer is thermally excited and emits low-energy fluorescence. This low-energy fluorescence is then absorbed by the optical refrigeration layer above. After absorbing the low-energy fluorescence, the optical refrigeration layer undergoes a photon conversion process, converting the low-energy fluorescence into high-energy photons and emitting them. Through the synergistic effect of the optical activation layer and the optical refrigeration layer, the thermal energy generated inside the resonator is converted into light energy and consumed, reducing the temperature of the device. At the same time, when the heat is lower than the critical temperature of the optical activation layer, it no longer emits light to drive the optical refrigeration layer to work, realizing the self-controlled temperature of the bulk acoustic wave resonator. This self-controlled temperature mechanism does not require an external control system and fully relies on the optical physical properties of the material itself to achieve temperature regulation, which is beneficial to improving the stability and power capacity of the resonator under high-frequency operation. The bulk acoustic wave resonator adopting this technology can effectively solve the problems of frequency drift and reduced power capacity caused by heating during high-frequency operation, and improve the application performance of the device in the field of high-frequency communication.

[0037] In some embodiments, the optical activation layer 700 is made of a thermoluminescent material.

[0038] The thermoluminescent material is selected to embody the material of the optical activation layer. The characteristic of the thermoluminescent material is that it can emit light after being heated. When the resonator operates, heat is generated, and the thermoluminescent material is used to absorb this heat. When the temperature rises to the excitation temperature of the thermoluminescent material, the material begins to emit low-energy fluorescence. This fluorescence can serve as the excitation light source for the optical refrigeration layer, driving the optical refrigeration layer to convert low-energy photons into high-energy photons, achieving a refrigeration effect and reducing the operating temperature of the resonator. Thus, by using the thermoluminescent material, it can be ensured that the optical activation layer can effectively respond to the heat generated by the resonator and start emitting light when the temperature reaches a certain level. This material can convert thermal energy into light energy, providing a driving light source for the subsequent optical refrigeration layer, thereby achieving the consumption of thermal energy and the temperature control of the device.

[0039] Specifically, when the bulk acoustic wave resonator operates, the piezoelectric layer generates heat due to acoustic wave loss. If the optical activation layer is made of a thermoluminescent material, this layer can be directly attached to the top electrode to quickly and effectively absorb the heat generated by the resonator. When the heat generated by the resonator raises the temperature of the optical activation layer to the excitation temperature of the thermoluminescent material, the thermoluminescent material begins to absorb thermal energy and release low-energy fluorescence. This low-energy fluorescence then irradiates the optical refrigeration layer, driving the optical refrigeration layer to work and convert low-energy photons into high-energy photons. Through the synergistic effect of the optical activation layer and the optical refrigeration layer, the thermal energy generated by the resonator is converted into light energy and consumed, thereby reducing the operating temperature of the resonator and avoiding the degradation and failure of device performance. Using the thermoluminescent material as the optical activation layer can achieve self-control regulation of the resonator temperature and improve the power capacity and stability of the device under high-frequency operation.

[0040] In some embodiments, the thermoluminescent material is any one of a halide, a sulfate, a sulfide, a binary oxide, or a ternary oxide that emits light when heated.

[0041] Halides refer to compounds formed by metal elements and halogen elements, such as sodium chloride, potassium iodide, etc. Sulfates refer to compounds containing sulfate ions, such as calcium sulfate, barium sulfate, etc. Sulfides refer to compounds formed by metal elements and sulfur elements, such as zinc sulfide, cadmium sulfide, etc. Binary oxides refer to oxides containing two elements, such as silicon dioxide, zinc oxide, etc. Ternary oxides refer to oxides containing three elements, such as yttrium aluminum garnet, barium titanate, etc. The common feature of these materials is that within a specific temperature range, when the temperature rises, the electrons inside the material will be thermally excited to high energy levels. When these high-energy-level electrons transition back to low energy levels, photons will be released, thereby generating a luminescence phenomenon. By defining that the light initiation layer is made of these specific material types, materials with excellent thermoluminescence performance can be more precisely selected, enabling the light initiation layer to more effectively absorb the heat generated by the resonator and emit low-energy fluorescence when a certain temperature is reached, providing a driving force for the subsequent optical refrigeration process. The limitation of the material type is beneficial for more easily finding thermoluminescent materials that meet the performance requirements in practical applications and simplifies the material screening and preparation process.

[0042] In some specific embodiments, the light initiation layer can be made of zinc sulfide material. Zinc sulfide is a typical sulfide thermoluminescent material. When the temperature rises, zinc sulfide can absorb thermal energy and emit fluorescence in the visible light band. For example, when the operating temperature of the resonator rises to 80 degrees Celsius, the zinc sulfide light initiation layer begins to absorb the heat generated by the resonator, and when the temperature reaches 100 degrees Celsius, the zinc sulfide material begins to emit green fluorescence. The heat-induced luminescence characteristics of the zinc sulfide material match the operating temperature range of the bulk acoustic wave resonator, and can effectively convert the thermal energy generated by the resonator into light energy, thereby reducing the operating temperature of the resonator and improving the power capacity and stability of the device. As a mature thermoluminescent material, zinc sulfide material has the advantages of low cost and easy preparation, which is beneficial for reducing the manufacturing cost of the self-controlled temperature bulk acoustic wave resonator and promoting the commercial application of this technology.

[0043] In certain embodiments, the optical refrigeration layer 800 is made of a photoluminescent material.

[0044] The photoluminescent material can achieve light wavelength conversion. The optical refrigeration layer is designed to absorb the fluorescence emitted by the light initiation layer and convert it into photons. The energy conversion process removes heat from the resonator, thereby achieving a refrigeration effect. The use of the photoluminescent material enables the conversion of thermal energy into light energy with high efficiency, thereby enhancing the refrigeration effect of the optical refrigeration layer. Specifically, the selection of the photoluminescent material can be optimized based on the emission spectrum of the light initiation layer to ensure that the optical refrigeration layer can effectively absorb the fluorescence emitted by the light initiation layer. The optical refrigeration layer can be prepared in a thin film structure and deposited on top of the light initiation layer to maximize the contact area with the fluorescence. When the resonator operates, the vibration of the piezoelectric layer generates heat, which is absorbed by the light initiation layer and converted into low-energy fluorescence. The low-energy fluorescence is then absorbed by the optical refrigeration layer, and the photoluminescent material in the optical refrigeration layer converts these low-energy fluorescence photons into high-energy photons and emits them. Since the energy of the emitted photons is higher than the energy of the absorbed photons, and the difference in energy comes from the thermal energy in the resonator, the refrigeration of the resonator is achieved.

[0045] Specifically, the optical refrigeration layer uses a photoluminescent material to absorb the low-energy fluorescence from the light initiation layer and convert these low-energy photons into high-energy photons. This energy conversion process effectively converts the thermal energy inside the resonator into light energy and dissipates it, achieving the cooling of the resonator. By selecting a suitable photoluminescent material, the energy conversion efficiency can be optimized, thereby enhancing the refrigeration effect of the optical refrigeration layer. For example, when the temperature of the resonator increases and causes the light initiation layer to emit fluorescence of a specific wavelength, the photoluminescent material in the optical refrigeration layer absorbs this fluorescence and emits photons with a shorter wavelength and higher energy through the photoluminescence process. This process continues, constantly consuming the thermal energy generated by the resonator in the form of light, maintaining the resonator at a lower operating temperature, and thereby enhancing the performance and stability of the device.

[0046] In some embodiments, the photoluminescent material is a halide perovskite or ytterbium-doped fluoride.

[0047] The material selection of the optical refrigeration layer is limited to halide perovskites or ytterbium-doped fluorides. Both halide perovskites and ytterbium-doped fluorides are photoluminescent materials, and the characteristic of such materials is that they can emit high-energy photons under the excitation of low-energy photons. Thus, when the light initiation layer absorbs the heat generated by the resonator and emits low-energy fluorescence, the optical refrigeration layer can be driven by the low-energy fluorescence and then convert high-energy photons. Through the cooperation of the light initiation layer and the optical refrigeration layer, the purpose of converting thermal energy into light energy and consuming it is achieved. Limiting the optical refrigeration layer to be made of halide perovskites or ytterbium-doped fluorides clarifies the selection range of the optical refrigeration layer material, ensuring that the optical refrigeration layer can effectively achieve optical refrigeration and thereby ensuring the device performance.

[0048] In some embodiments, both the bottom electrode 300 and the top electrode 500 are made of any one or more materials selected from Au, Ag, Ru, W, Mo, Ir, Al, Pt, Nb, and Hf.

[0049] In some embodiments, the piezoelectric layer 400 is made of any one material selected from AlN, , , and so on.

[0050] In some embodiments, the substrate 100 is made of any one material selected from Si, sapphire, and SiC; the support layer 200 is made of , any one or more materials selected from SiC and so on.

[0051] The present invention provides a filter, including the self - controlled temperature bulk acoustic wave resonator in the above - mentioned embodiments.

[0052] Referring to Attached Figure 2 and Attached Figure 3 , the present invention provides a preparation method for preparing the self - controlled temperature bulk acoustic wave resonator in the above - mentioned embodiments, including the following steps: S1. After making a groove on the upper surface of the substrate, grow a sacrificial layer on the groove; S2. Sequentially make a support layer, a bottom electrode, a piezoelectric layer, and a top electrode covering the groove on the upper surface of the substrate; S3. Spin - coat a photo - initiation layer on the top electrode; S4. After the photo - initiation layer is dried, spin - coat a photo - cooling layer on the photo - initiation layer; S5. Release the sacrificial layer to form a cavity between the substrate and the support layer, thus obtaining the self - controlled temperature bulk acoustic wave resonator.

[0053] In step S1, making a groove on the upper surface of the substrate provides a structural basis for forming a cavity subsequently, and the groove can be made by an etching process. The sacrificial layer grows on the groove and is used to be released in subsequent steps to form a cavity structure.

[0054] In step S2, the support layer, the bottom electrode, the piezoelectric layer, and the top electrode are sequentially made on the upper surface of the substrate, and these thin - film layers together construct the basic structure of the bulk acoustic wave resonator. The support layer is used to support the upper thin - film layers, the bottom electrode and the top electrode are used to apply electrical signals, and the piezoelectric layer is a functional layer for realizing acoustic - electrical conversion.

[0055] In steps S3 and S4, the photo - initiation layer and the photo - cooling layer are prepared on the upper surface of the top electrode by a spin - coating process. The spin - coating method is a common method for preparing thin films and can achieve uniform coverage of the thin films. The photo - initiation layer is spin - coated first, and after drying, the photo - cooling layer is spin - coated to form a laminated structure.

[0056] In step S5, the sacrificial layer is released, and a cavity is formed between the substrate and the support layer. The formation of the cavity structure endows the resonator with good acoustic performance. The release of the sacrificial layer usually adopts a wet etching process. By selecting a suitable etching solution, the sacrificial layer is selectively removed on the premise of not damaging other film layers.

[0057] Specifically, aiming at the problem that the high-frequency bulk acoustic wave resonator generates heat and causes device failure, this method provides an effective way to fabricate a self-temperature-controlled bulk acoustic wave resonator. By fabricating a photoinitiation layer and a photorefrigeration layer on the top electrode of the resonator, the conversion and consumption of thermal energy into light energy are realized. When the resonator operates and generates heat, the photoinitiation layer absorbs the heat and emits low-energy fluorescence. The photorefrigeration layer converts into high-energy photons under the drive of the low-energy fluorescence, thereby consuming the thermal energy in the form of light energy, reducing the device temperature, enhancing the device power capacity, and ensuring the stable operation of the device at high frequencies. The fabrication method includes making a groove and a sacrificial layer on the substrate to prepare for the subsequent formation of the cavity structure; fabricating each film layer constituting the resonator and the light energy conversion functional layer on the upper surface of the substrate through processes such as deposition and spin coating; and finally forming a bulk acoustic wave resonator with self-temperature-controlled function by releasing the sacrificial layer.

[0058] In some specific embodiments, first, the substrate is cleaned and dried with acetone and hydrofluoric acid, then a 3-μm deep groove is fabricated on the surface of the silicon substrate by plasma etching, and then a sacrificial layer is grown by PVD method with a thickness of 3.1 μm. Subsequently, the sacrificial layer is polished, and a support layer with a thickness of 50 nm is grown by plasma-enhanced CVD technology. Then, a bottom electrode with a thickness of 500 nm is deposited on the surface of the sacrificial layer by PVD method. Then, a piezoelectric layer with a thickness of 1 μm is grown on the bottom electrode by PVD. Then, a top electrode with a thickness of 500 nm is grown on the piezoelectric layer by PVD. Then, a 200-nm thick photoinitiation layer is grown on the top electrode by spin coating. After drying, a 300-nm thick photorefrigeration layer is spin-coated continuously. Finally, the above resonator is placed in gaseous hydrogen fluoride for release, and the sacrificial layer is removed by dry etching to fabricate the resonator.

[0059] In some specific embodiments, first, a silicon substrate is selected, and a groove with a depth of 2 micrometers is fabricated on the upper surface of the silicon substrate through photolithography and etching processes. Subsequently, a silicon dioxide sacrificial layer with a thickness of 0.5 micrometers is grown on the groove by chemical vapor deposition. Then, on the upper surface of the silicon substrate, a silicon nitride support layer with a thickness of 0.2 micrometers is deposited by chemical vapor deposition; a molybdenum bottom electrode, an aluminum nitride piezoelectric layer, and a gold top electrode are sequentially deposited by magnetron sputtering, with thicknesses of 0.1 micrometer, 1 micrometer, and 0.1 micrometer, respectively. Then, a thermoluminescent halide photoinitiation layer is spin-coated on the upper surface of the gold top electrode at a spin-coating speed of 1000 revolutions per minute for 30 seconds and dried at 100 degrees Celsius for 30 minutes. After the photoinitiation layer is dried, a halide perovskite photothermal cooling layer is spin-coated on the upper surface of the photoinitiation layer at a spin-coating speed of 800 revolutions per minute for 30 seconds. Finally, the silicon dioxide sacrificial layer is released using a hydrofluoric acid solution to form a cavity structure, and a self-controlled temperature bulk acoustic wave resonator is fabricated.

[0060] The self-controlled temperature bulk acoustic wave resonator prepared through the above embodiments can effectively solve the heating problem under high-frequency operation and improve the performance and reliability of the device.

[0061] In this document, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0062] The description with reference to terms such as "one embodiment", "certain embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0063] The above description is only for the embodiments of the present invention and is not intended to limit the protection scope of the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A self-controlled temperature bulk acoustic wave resonator, comprising a substrate (100), a support layer (200), a bottom electrode (300), a piezoelectric layer (400) and a top electrode (500) stacked in sequence, wherein a cavity (600) is provided between the substrate (100) and the support layer (200), characterized in that: A light start layer (700) and a light cooling layer (800) are sequentially stacked on the top electrode (500); the light start layer (700) is used to absorb heat generated by the resonator and stimulate low-energy fluorescence when a critical temperature is reached; the light cooling layer (800) can convert high-energy photons under the drive of the low-energy fluorescence; the light start layer (700) and the light cooling layer (800) cooperate to convert thermal energy into light energy for consumption.

2. The self-temperature-controlled bulk acoustic wave resonator according to claim 1, characterized in that: The light-activated layer (700) is made of thermoluminescent material.

3. The self-temperature-controlled bulk acoustic wave resonator according to claim 2, characterized in that: The thermoluminescent material is any one of halides, sulfates, sulfides, binary oxides or ternary oxides that emit light under heat.

4. The self-temperature-controlled bulk acoustic wave resonator according to claim 1, characterized in that: The optical cooling layer (800) is made of photoluminescent material.

5. The self-temperature-controlled bulk acoustic wave resonator according to claim 4, characterized in that: The photoluminescent material is a halide perovskite or an ytterbium-doped fluoride.

6. The self-temperature-controlled bulk acoustic wave resonator according to claim 1, characterized in that: The bottom electrode (300) and the top electrode (500) are both made of any one or more materials selected from the group consisting of Au, Ag, Ru, W, Mo, Ir, Al, Pt, Nb, and Hf.

7. The self-temperature-controlled bulk acoustic wave resonator according to claim 1, characterized in that: The piezoelectric layer (400) is made of AlN, , , Made of any material.

8. The self-temperature-controlled bulk acoustic wave resonator according to claim 1, characterized in that: The substrate (100) is made of any one of Si, sapphire and SiC; the support layer (200) is made of , SiC or any one or more materials.

9. A filter, characterized in that: It comprises the self-temperature-controlled bulk acoustic wave resonator as claimed in any one of claims 1 to 8.

10. A method for preparing the self-temperature-controlled bulk acoustic wave resonator according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. After making a groove on the upper surface of the substrate, a sacrificial layer is grown on the groove; S2. A support layer, a bottom electrode, a piezoelectric layer and a top electrode covering the groove are sequentially formed on the upper surface of the substrate; S3. Spin-coating a light-activated layer on the top electrode; S4. After the optical activation layer is dried, a photorefrigeration layer is spin-coated on the optical activation layer; S5. releasing the sacrificial layer to form a cavity between the substrate and the supporting layer, thereby obtaining the self-temperature-controlled bulk acoustic wave resonator.

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