Miniature piezoelectric antenna based on film bulk acoustic resonator structure

Abstract

The invention provides a miniature piezoelectric antenna based on a film bulk acoustic resonator structure, which sequentially comprises a film bulk acoustic resonator, an insulating passivation layer and a second piezoelectric layer from bottom to top, and is characterized in that the film bulk acoustic resonator structure is used for generating acoustic waves and transmitting the acoustic waves to the second piezoelectric layer; the second piezoelectric layer is also used for receiving sound waves from the second piezoelectric layer and generating corresponding electric signals; the second piezoelectric layer is used for enabling standing waves in the second piezoelectric layer in the thickness direction to be in the same phase or most of the standing waves are in the same phase under excitation of received sound waves, so that electromagnetic waves are radiated outwards, and the second piezoelectric layer is also used for generating sound waves under the action of electromagnetic wave electric field components after receiving external electromagnetic waves. And the generated sound wave is transmitted to the film bulk acoustic wave resonator. The miniature piezoelectric antenna is small in size, can realize multi-frequency resonance work, remarkably improves the radiation efficiency of the piezoelectric material, and is one of future solutions for miniaturization of a wireless communication system.

Description

Technical Field

[0001] The present invention belongs to the technical fields of micro-nano electronics and microwave communication, and particularly relates to a micro piezoelectric antenna based on a thin film bulk acoustic resonator structure. Background Art

[0002] In recent years, with the rapid development of wearable devices, implantable medical devices, and wireless communication technologies, the demand for miniaturization and intelligence of electronic devices has been increasing. However, the volume and energy consumption of traditional antennas in these applications limit the overall performance of the system, especially in environments with extremely strict requirements for size and power consumption, this problem is particularly prominent.

[0003] To address the challenges of antenna miniaturization, micro-acoustic actuated antennas based on thin film bulk acoustic resonators (FBARs) have received extensive attention in recent years due to their micron-scale size, low power consumption, and high operating frequency characteristics.

[0004] The patent application for invention with publication number CN109103582A discloses a nano-mechanical acoustic antenna based on a thin film bulk acoustic resonator structure and a manufacturing method thereof. The antenna includes a substrate, a magnetostrictive layer, and a piezoelectric stack; the piezoelectric stack includes a piezoelectric thin film, a lower electrode, and an upper electrode; the lower electrode is located between the piezoelectric thin film and the substrate, and the magnetostrictive layer and the upper electrode are located above the piezoelectric thin film. At the position of the lower electrode, a through hole is provided in the substrate for electrical connection of the lower electrode. The antenna disclosed in this patent application has a smaller size and simple and reliable process steps. The piezoelectric layer is mainly used to generate corresponding deformations due to voltage changes, thereby generating acoustic waves; the magnetostrictive layer can generate oscillating magnetic currents due to the internal alternating magnetization under the excitation of acoustic waves, thereby generating corresponding electromagnetic waves. However, the performance and size of the antenna provided by this invention patent are limited by the magnetostrictive material and it is difficult to have further improvement.

[0005] The patent application for invention with publication number CN118693512A discloses a magnetoelectric antenna based on a thin film bulk acoustic resonator structure excited by a flexible transverse field. It includes a flexible support substrate, a piezoelectric single crystal is provided on the flexible support substrate, a coplanar electrode is provided on the piezoelectric single crystal, the coplanar electrode is composed of an input electrode and a ground electrode, and a magnetostrictive thin film is provided between the input electrode and the ground electrode. The magnetoelectric antenna of this invention operates in an in-plane vibration mode and has a stronger magnetoelectric coupling coefficient, which can effectively improve the radiation power; compared with the traditional cavity FBAR magnetoelectric antenna, the magnetoelectric antenna excited by the flexible transverse field disclosed in this patent application not only has a simple manufacturing process and is compatible with the CMOS process, but also can work in flexible application scenarios and has a high quality factor. Similarly, the performance and size of the antenna disclosed in this patent application are limited by the magnetostrictive material.

[0006] Different from traditional electrical antennas, micro-acoustic actuated antennas utilize the coupling mechanism between acoustic waves and electromagnetic waves to achieve signal reception and transmission, thus showing stronger adaptability in complex transmission environments. Currently, mainstream acoustic actuated micro-antennas usually use magnetostrictive materials as the radiation layer, and their performance is restricted by the self-loss of magnetostrictive materials and the manufacturing process. At the same time, the manufacturing difficulty of micro-antennas is relatively high, which affects their practicality and popularization.

[0007] On the other hand, piezoelectric signal transmitters that directly utilize the piezoelectric effect of piezoelectric materials to generate electromagnetic radiation usually operate in the KHz frequency band, with extremely low radiation efficiency and difficulty in further miniaturization. Summary of the Invention

[0008] The present invention provides a micro piezoelectric antenna based on a thin film bulk acoustic resonator structure, which has a smaller size and stronger electromagnetic radiation ability.

[0009] The present invention provides a micro piezoelectric antenna based on a thin film bulk acoustic resonator structure, which sequentially includes a thin film bulk acoustic resonator structure and a second piezoelectric layer from bottom to top: The thin film bulk acoustic resonator structure is used to generate acoustic waves, transmit acoustic waves to the second piezoelectric layer, and also used to receive acoustic waves from the second piezoelectric layer and generate corresponding electrical signals; The second piezoelectric layer is used to make the standing wave along the thickness direction inside the second piezoelectric layer in the same phase or mostly in the same phase under the excitation of the received acoustic wave, that is, to make more than 70% of the acoustic waves in the standing wave distribution in the second piezoelectric layer in the same phase, so as to realize the external radiation of electromagnetic waves. It is also used to generate acoustic waves under the action of the electric field component of the external electromagnetic wave after receiving the external electromagnetic wave, and transmit the generated acoustic waves to the thin film bulk acoustic resonator structure.

[0010] Preferably, the thin film bulk acoustic resonator structure includes a first piezoelectric layer, and the thicknesses of the first piezoelectric layer and the second piezoelectric layer are respectively 100 nm - 10 μm independently.

[0011] The present invention sets the thicknesses of the appropriate first piezoelectric layer and the second piezoelectric layer. With the goal that the standing wave along the thickness direction inside the second piezoelectric layer is in the same phase or mostly in the same phase under the excitation of acoustic waves, the working frequency of the antenna and the geometric parameters of each layer of the antenna can be obtained by modeling and calculating the set antenna through multi-physics field simulation software.

[0012] Further preferably, a multi-physics field simulation software is applied to model and calculate the antenna, including: setting the piezoelectric effect of the piezoelectric layer and scanning the geometric parameters of each layer of the micro piezoelectric antenna, calculating and optimizing the standing wave distribution, impedance and transmission parameters of the micro piezoelectric antenna, and the optimization objective is that the standing wave inside the second piezoelectric layer along the thickness direction is in the same phase or mostly in the same phase under the excitation of the received sound wave, so as to obtain the operating frequency of the antenna provided by the present invention and the geometric parameters of the antenna provided by the present invention.

[0013] Preferably, the second piezoelectric layer is composed of an alloy or a multi-layer structure of one or more materials among aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lithium niobate, and lead zirconate titanate piezoelectric materials.

[0014] Further preferably, the second piezoelectric layer is an alloy or a multi-layer structure of one or more materials among zinc oxide, aluminum nitride, and lithium niobate piezoelectric materials.

[0015] The further preferably provided materials of the present invention have low mechanical loss and hysteresis loss. Due to the low mechanical loss, the conversion efficiency of sound waves can be improved during the electro-acoustic conversion process. Due to the low hysteresis loss, the efficiency of acoustic-polarization conversion can be improved, thereby improving the radiation ability of the second piezoelectric layer.

[0016] Preferably, the lateral dimension of the second piezoelectric layer is 20μm - 1000μm.

[0017] Preferably, the thin film bulk acoustic resonator structure includes a cavity-type FBAR, a back-etched FBAR, a solid-assembled FBAR, or an HBAR structure.

[0018] The FBAR structure is a cavity-type FBAR, and the cavity is formed by setting a sacrificial layer and releasing the sacrificial layer through dry or wet etching; or the FBAR structure is a back-etched FBAR, and the cavity is formed by back-etching the substrate; or the FBAR structure is a solid-assembled FBAR, which is realized by depositing a Bragg reflector layer on the substrate; the piezoelectric antenna based on the cavity-type FBAR, back-etched FBAR, and solid-assembled FBAR structures can operate in the first and second order resonance modes. Or the antenna operates in the high overtone bulk acoustic wave mode, i.e., the HBAR mode, which is realized by retaining the sacrificial layer in the cavity region, or by directly depositing the FBAR structure on the substrate without manufacturing a cavity to realize the HBAR structure.

[0019] Preferably, the thin film bulk acoustic resonator structure sequentially includes a substrate, a cavity, a lower electrode layer, a first piezoelectric layer, and an upper electrode layer from bottom to top; Alternatively, from bottom to top, it sequentially includes a substrate, a cavity, a seed layer, a lower electrode layer, a first piezoelectric layer, an upper electrode layer, and an insulating passivation layer. Among them, the seed layer, the first piezoelectric layer, and the substrate enclose a cavity, or a cavity is etched back inside the substrate to the seed layer.

[0020] Further preferably, materials such as aluminum nitride are used for the seed layer to improve the quality of subsequent thin film deposition, and the thickness is 5nm - 200nm.

[0021] The insulating passivation layer provided in the specific embodiments of the present invention is used to protect the metal of the upper electrode layer and adjust the antenna resonance frequency.

[0022] Further preferably, the lower electrode layer and the upper electrode layer are each independently composed of one or more materials among aluminum, gold, molybdenum, chromium, and titanium metals, and the thickness is 10nm - 2μm.

[0023] Preferably, materials such as aluminum nitride, scandium-doped aluminum nitride, aluminum oxide, and silicon oxide are used for the insulating passivation layer to protect the upper electrode layer during the process, and the thickness is 10nm - 2μm.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: For the first time, the present invention utilizes the acoustic wave excitation effect generated by the thin film bulk acoustic resonator (FBAR) structure to make the standing wave inside the second piezoelectric layer along the thickness direction in the same phase or mostly in the same phase. As a result, the polarization rotation that is frequency-synchronized with the acoustic wave inside is also in the same phase or mostly in the same phase, and then the internal electric dipole oscillation radiation is enabled to realize the antenna radiating electromagnetic waves outward.

[0025] Since the acoustic wave wavelength is 4 - 5 orders of magnitude smaller than the electromagnetic wave wavelength of the same frequency, and the overall size of the antenna provided in this application needs to match the acoustic wave wavelength. Compared with the antenna disclosed in the prior art that matches the electromagnetic wave wavelength, the size is smaller, breaking through the size limitation of traditional antennas and realizing a micrometer-scale miniaturized design.

[0026] With the help of the resonance characteristics of the FBAR, the antenna provided by the present invention can operate in the millimeter wave and even sub-millimeter wave bands, and is suitable for high-frequency communication and sensing fields. The antenna obtained through the FBAR structure and the design of the second piezoelectric layer provided by the present invention, compared with the magnetostrictive-piezoelectric structure of the magnetoelectric antenna, utilizes the electromechanical coupling between the two piezoelectric layers to improve the acoustic-electric conversion efficiency, enhance the electromagnetic radiation ability and overall performance of the antenna. The antenna provided by the present invention can operate at 2 - 4GHz.

[0027] In addition, this antenna structure is compatible with existing CMOS and MEMS manufacturing processes, which helps to achieve large-scale production, and has broad application prospects in future wireless communication, wearable medical, micro sensors and other fields. Description of the Drawings

[0028] Figure 1 Schematic diagram of the structure of the micro piezoelectric acoustic actuator antenna based on thin film bulk acoustic resonators provided by a specific embodiment of the present invention, in which the sacrificial layer material in the cavity 101 is released, and the cavity is filled with air to form a suspended structure; Figure 2 Schematic diagram of the structure of the micro piezoelectric acoustic actuator antenna based on thin film bulk acoustic resonators provided by a specific embodiment of the present invention, in which a patterned sacrificial layer material is deposited on the substrate 100, and the cavity 101 is formed by releasing the sacrificial layer.

[0029] Figure 3 Schematic diagram of the structure of the micro piezoelectric acoustic actuator antenna based on thin film bulk acoustic resonators provided by a specific embodiment of the present invention, in which the cavity 101 forms a back-etched FBAR structure by back-etching the substrate 100; Figure 4 Schematic diagram of the structure of the micro piezoelectric acoustic actuator antenna based on thin film bulk acoustic resonators provided by a specific embodiment of the present invention, in which the area 101 is composed of Bragg reflector layer material; Figure 5 Schematic diagram of the structure of the micro piezoelectric acoustic actuator antenna based on thin film bulk acoustic resonators provided by a specific embodiment of the present invention, in which the sacrificial layer material in the cavity 101 is retained to form an HBAR structure; Figure 6 Schematic diagram of the structure of the micro piezoelectric acoustic actuator antenna based on thin film bulk acoustic resonators provided by a specific embodiment of the present invention, in which the cavity 101 area is not formed, and the thin films 102 - 107 are directly deposited on the substrate 100 to form an HBAR structure; Figure 7 Schematic diagram of the performance test system of the micro piezoelectric antenna provided by a specific embodiment of the present invention; Figure 8 Provided by a specific embodiment of the present invention Figure 1 Performance test result diagram of the micro piezoelectric antenna based on cavity-type FBAR shown in, including S 22 , S 21 and S 12 parameter test; Figure 9 Provided by a specific embodiment of the present invention Figure 1 Performance test result diagram of the micro piezoelectric antenna based on cavity-type FBAR shown in, including S 22 , S 21 and S 12 parameter test; Figure 10 Provided by a specific embodiment of the present invention Figure 4Performance test results of the HBAR-based micro piezoelectric antenna in its multiple resonance modes, including S 22 , S 21 and S 12 parameter tests; Among them, 100 - substrate layer, 101 - cavity, 102 - seed layer, 103 - lower electrode layer, 104 - first piezoelectric layer, 105 - upper electrode layer, 106 - insulating passivation layer, 107 - second piezoelectric layer. Detailed implementation manners

[0030] The present invention provides a micro piezoelectric acoustic actuating antenna based on a thin film bulk acoustic resonator, including a substrate, a cavity, a seed layer, an FBAR structure, an insulating passivation layer, and a second piezoelectric layer; compared with traditional antennas, the present invention uses piezoelectric materials to transmit and receive electromagnetic waves, realizes the miniaturization of the antenna, improves the radiation efficiency of the antenna, and finally obtains a new type of micro antenna.

[0031] A specific embodiment of the present invention provides a micro piezoelectric antenna based on a thin film bulk acoustic wave structure, which sequentially includes a thin film bulk acoustic resonator structure and a second piezoelectric layer from bottom to top: The thin film bulk acoustic resonator structure provided by the specific embodiment of the present invention is used to generate acoustic waves and transmit the acoustic waves to the second piezoelectric layer, and is also used to receive the acoustic waves from the second piezoelectric layer and generate corresponding electrical signals; The second piezoelectric layer provided by the specific embodiment of the present invention is used to make the standing wave inside the second piezoelectric layer along the thickness direction be in the same phase or mostly in the same phase under the excitation of the received acoustic waves, so as to realize the outward radiation of electromagnetic waves, and is also used to generate acoustic waves under the action of the electric field component of the external electromagnetic waves after receiving the external electromagnetic waves, and transmit the generated acoustic waves to the thin film bulk acoustic resonator.

[0032] A specific embodiment of the present invention proposes a micro piezoelectric antenna based on an FBAR structure. During the emission process, the antenna generates acoustic waves by using the FBAR structure and drives the piezoelectric material to vibrate. After being excited by the acoustic waves, the piezoelectric material will perform synchronous polarization rotation inside under the action of the piezoelectric effect and thus radiate outward. During the reception process, after the antenna receives electromagnetic waves, the piezoelectric material generates acoustic waves under the action of the electric field component of the electromagnetic waves, and the acoustic waves are transmitted into the FBAR structure and converted into electrical signals on the upper and lower electrodes, thereby realizing the efficient radiation and reception of electromagnetic waves. With the resonance characteristics of the FBAR structure, the antenna can not only effectively realize miniaturization, but also has the potential to expand to high frequency bands such as millimeter waves and sub - millimeter waves, so as to meet the requirements for miniaturized, high - frequency, and low - power antennas in complex environments. This technology has broad application prospects in the fields of wearable electronics, implantable medical devices, portable intelligent terminals, etc., and provides new ideas and technical bases for the research and application of next - generation high - performance micro antennas.

[0033] The antenna provided by the specific embodiments of the present invention will be further described below in conjunction with specific examples. For example Figure 1 FIG. is a schematic structural diagram of a micro piezoelectric acoustic actuator antenna based on a thin film bulk acoustic resonator provided by the present invention; from bottom to top, it sequentially includes a substrate 100, a cavity 101, a seed layer 102, a lower electrode layer 103, a first piezoelectric layer 104, an upper electrode layer 105, an insulating passivation layer 106, and a second piezoelectric layer 107; the lower electrode layer 103, the first piezoelectric layer 104, and the upper electrode layer 105 together form a thin film bulk acoustic resonator (FBAR) structure, the seed layer 102 is located below the lower electrode layer 103 of the thin film bulk acoustic resonator structure, and the insulating passivation layer 106 is used to isolate the upper electrode layer 105 and the second piezoelectric layer 107 of the FBAR structure; the cavity 101 is located between the upper surface of the substrate 100 and the seed layer 102.

[0034] A manufacturing and processing method of the present invention is as follows: 1) Take the insulating substrate 100 and place it in acetone, isopropyl alcohol, and deionized water for ultrasonic cleaning. Use RIE or ICP etching process to etch a cavity 101 on the substrate, with a depth of 3 μm.

[0035] 2) Deposit 3 μm - 5 μm of phosphosilicate glass (PSG) as a sacrificial layer material on the substrate 100 through processes such as chemical vapor deposition (CVD) or physical vapor deposition (PVD). Then, remove the excess PSG material through chemical mechanical polishing process (CMP), and only retain the sacrificial layer in the cavity 101.

[0036] 3) Deposit a 30 nm aluminum nitride seed layer 102 and 100 nm molybdenum as the lower electrode layer 103 on the substrate through processes such as CVD or magnetron sputtering, and pattern the seed layer 102 and the lower electrode layer 103 through ICP etching or photolithography - lift - off process.

[0037] 4) Deposit a 350 nm thick c - axis oriented scandium - doped aluminum nitride thin film as the first piezoelectric layer 104 through processes such as magnetron sputtering, CVD, or thermal evaporation, and pattern the first piezoelectric layer 104 through ICP etching or photolithography - lift - off process.

[0038] 5) Deposit a 150 nm molybdenum upper electrode layer 105 and a 120 nm aluminum nitride insulating passivation layer 106 on the first piezoelectric layer 104 through processes such as CVD or magnetron sputtering, and pattern the upper electrode layer 105 and the insulating passivation layer 106 through ICP etching or photolithography - lift - off process.

[0039] 6) Release the sacrificial layer by wet etching with hydrofluoric acid or other methods to form the cavity 101. 7) A c-axis oriented zinc oxide thin film with a thickness of 850 nm is sputtered by magnetron sputtering above the insulating passivation layer 106 as the second piezoelectric layer 107, and the patterned second piezoelectric layer 107 is formed by ICP etching or photolithography-lift-off process.

[0040] The substrate 100 material provided in the specific implementation of the present invention can be selected from one or a combination of silicon, silicon oxide, sapphire, silicon carbide, glass, quartz, etc. The cavity 101 structure is etched by wet etching, dry etching methods such as ICP and RIE. The pattern of the cavity can be any shape such as triangle, quadrilateral, pentagon, circle, etc., with a lateral dimension of 20 μm - 1000 μm and a thickness of 500 nm - 10 μm.

[0041] The seed layer 102 provided in the specific implementation of the present invention is made of materials such as aluminum nitride and is used to improve the thin film deposition quality of the lower electrode layer 103, with a thickness of 5 nm - 200 nm.

[0042] The lower electrode layer 103 provided in the specific implementation of the present invention is composed of one or more materials among metals such as aluminum, gold, molybdenum, chromium, titanium, etc., with a thickness of 10 nm - 2 μm. The lower electrode layer 103 can be fabricated with patterning through processes such as lift-off, dry etching, and wet etching.

[0043] The first piezoelectric layer 104 provided in the specific implementation of the present invention is composed of one or more materials among piezoelectric materials such as aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, etc., and the thickness of the first piezoelectric layer is 100 nm - 10 μm.

[0044] The upper electrode layer 105 provided in the specific implementation of the present invention is composed of one or more materials among metals such as aluminum, gold, molybdenum, chromium, titanium, etc., with a thickness of 10 nm - 2 μm. The upper electrode layer 105 can be fabricated with patterning through processes such as lift-off, dry etching, and wet etching.

[0045] The insulating passivation layer 106 provided in the specific implementation of the present invention is a combination of one or more materials among aluminum nitride, scandium-doped aluminum nitride, aluminum oxide, silicon oxide, etc.

[0046] The second piezoelectric layer 107 provided in the specific implementation of the present invention is composed of one or more materials among piezoelectric materials such as aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lithium niobate, etc., and is patterned through processes such as lift-off, dry etching, and wet etching. The thickness of the second piezoelectric layer is 100 nm - 10 μm.

[0047] The above example is an example of the cavity-type FBAR structure described in the present invention, that is, the cavity is formed by setting a sacrificial layer and releasing the sacrificial layer through dry or wet etching to form a cavity suspended structure as Figure 1 and Figure 2 shown.

[0048] The back-etching of the substrate 100 to form the cavity 101 provided in the specific implementation of the present invention is as Figure 3 shown, and a back-etched FBAR structure can be formed; in addition, a solidly mounted (SMR) type FBAR can be constructed by setting a Bragg reflector layer on the substrate 100, as Figure 4 shown; it is also possible to make the FBAR operate in the high-mode bulk acoustic wave mode (i.e., HBAR) by retaining the sacrificial layer in the cavity, as Figure 5 shown; the HBAR structure can also be formed by depositing the thin film layers 102-107 directly on the substrate 100 by omitting the processing technology in the 101 area, as Figure 6 shown. Regardless of which structure is used, the antenna based on the present invention can drive the piezoelectric material at the resonance frequency of the corresponding structure to complete the functions of receiving and transmitting electromagnetic radiation, thereby constructing a new type of micro piezoelectric antenna.

[0049] A schematic diagram of a test system for a micro piezoelectric acoustic actuator antenna based on a cavity-type FBAR described in this example is as Figure 7 shown. This test system measures the gain of the piezoelectric antenna by the gain comparison method, and the system measures the antenna gain by the gain comparison method. During the test, the port 1 of the vector network analyzer is externally connected to a receiving antenna with a nominal gain, and the port 2 is connected to the micro piezoelectric acoustic actuator antenna described in the present invention. The system simultaneously records the echo loss curve (S 22 ) of the piezoelectric antenna and the transmission coefficient curves (S 21 and S 12 ) between the transmitting antenna and the receiving antenna. Among them, the S 22 curve reflects the ratio of the incident signal energy to the reflected signal energy of the antenna, and an obvious peak will appear near the resonance frequency of the antenna, indicating that the antenna operates in this mode; while the S 21 and S 12 curves represent the ratio of the transmission signals of the transmitting antenna and the receiving antenna. The coincidence of the S 12 and S 21 curves indicates that the test system network has reciprocity. When the S 21 (or S 12 ) curve forms the largest rising peak at the peak of the S 22 , it indicates that the tested piezoelectric antenna radiates the strongest signal at this frequency, that is, this frequency is the working center frequency of the antenna.

[0050] The performances of the first-order resonance mode and the second-order resonance mode provided in the specific embodiment of the present invention are respectively as Figure 8 and Figure 9 shown. At the resonance frequency of the antenna, that is, at the frequency corresponding to the peak of S 22 , the transmission coefficient S 21 / S 12Reaching the maximum value indicates that the intensity of the piezoelectric antenna radiating and receiving electromagnetic signals at this frequency reaches the highest, that is, the antenna operates within this frequency band; as Figure 10 shown, the micro piezoelectric acoustic actuator antenna based on HBAR described in this embodiment can operate in multiple higher-order resonance modes to broaden the operating frequency band of the antenna.

[0051] As Figure 8 shown, the peak of the S 22 curve is located at 1.85 GHz, that is, the first-order thickness resonance frequency of the antenna is 1.85 GHz, and the corresponding S 12 and S 21 curves also reach the maximum value at 1.85 GHz, indicating that the operating center frequency of the piezoelectric antenna is 1.85 GHz.

[0052] As Figure 9 shown, the peak of the S 22 curve is located at 3.92 GHz, that is, the second-order thickness resonance frequency of the antenna is 3.91 GHz, and the corresponding S 12 and S 21 curves also reach the maximum value at 3.91 GHz, indicating that the operating center frequency of the piezoelectric antenna is 3.92 GHz.

[0053] As Figure 10 shown, the peak envelope of the S 22 curve reaches the peak within the frequency band near 2 GHz, that is, the resonance characteristics of the piezoelectric antenna based on the HBAR structure are the most obvious in the 12 - 15 higher-order resonance modes in the frequency band near 2 GHz, and the corresponding S 12 and S 21 curves also reach the maximum value at each peak point of the S 22 within the frequency band near 2 GHz, indicating that the piezoelectric antenna operates in the 12 - 15 higher-order resonance frequency bands near 2 GHz.

[0054] The above content is only the preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been described in detail through the above embodiments, it is not used to limit its scope of application. For those skilled in the art, without departing from the technical solution of the present invention, based on the technical content disclosed in this specification, certain adjustments or improvements are made to form a functionally equivalent deformation implementation scheme, which should be regarded as belonging to the technical scope of the present invention. Any simple modification, equivalent replacement or adjustment made to the above embodiments based on the technical essence of the present invention still falls within the protection scope of the present invention.

Claims

1. A micro piezoelectric antenna based on a thin film bulk acoustic wave resonator structure, characterized in that: From bottom to top, it includes the film bulk acoustic wave resonator structure and the second piezoelectric layer: The thin film bulk acoustic wave resonator structure is used to generate sound waves and transmit the sound waves to the second piezoelectric layer, and is also used to receive the sound waves from the second piezoelectric layer and generate corresponding electrical signals; The second piezoelectric layer is used to make the standing waves along the thickness direction inside the second piezoelectric layer in the same phase during resonance or make more than 70% of the sound waves distributed in the second piezoelectric layer in the same phase under the excitation of the received sound waves, thereby realizing the outward radiation of electromagnetic waves. It is also used to generate sound waves under the action of the electric field component of the electromagnetic waves after receiving external electromagnetic waves, and transmit the generated sound waves to the thin film bulk acoustic wave resonator structure.

2. The micro piezoelectric antenna based on a thin film bulk acoustic wave resonator structure according to claim 1 is characterized in that: The FBAR structure includes a first piezoelectric layer, and the thickness of the first piezoelectric layer and the second piezoelectric layer are 100 nm-10 μm respectively.

3. The micro piezoelectric antenna based on a thin film bulk acoustic wave resonator structure according to claim 1, characterized in that: The second piezoelectric layer is composed of an alloy or a multilayer structure of one or more materials selected from the group consisting of aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lithium niobate, and lead zirconate titanate piezoelectric materials.

4. The micro piezoelectric antenna based on a thin film bulk acoustic wave resonator structure according to claim 3 is characterized in that: The second piezoelectric layer is an alloy or a multilayer structure of one or more materials selected from zinc oxide, aluminum nitride, and lithium niobate piezoelectric materials.

5. The micro piezoelectric antenna based on a thin film bulk acoustic wave resonator structure according to claim 1, characterized in that: The lateral dimension of the second piezoelectric layer is 20 μm-1000 μm.

6. The micro piezoelectric antenna based on a thin film bulk acoustic wave resonator structure according to claim 1, characterized in that: The thin film bulk acoustic wave resonator structure is a cavity type FBAR, a back-etched type FBAR, a solid assembly type FBAR or a HBAR structure.

7. The micro piezoelectric antenna based on a thin film bulk acoustic wave resonator structure according to claim 1, characterized in that: The thin film bulk acoustic wave resonator structure comprises, from bottom to top, a substrate, a cavity, a lower electrode layer, a first piezoelectric layer and an upper electrode layer; Alternatively, from bottom to top, it includes a substrate, a cavity, a seed layer, a lower electrode layer, a first piezoelectric layer, an upper electrode layer and an insulating passivation layer, wherein the seed layer, the first piezoelectric layer and the substrate surround a cavity, or a cavity is back-etched from the bottom of the substrate to the seed layer.

8. The micro piezoelectric antenna based on a thin film bulk acoustic wave resonator structure according to claim 7, characterized in that: The seed layer is made of materials such as aluminum nitride and is used to improve the quality of subsequent thin film deposition, with a thickness of 5nm-200nm.

9. The micro piezoelectric antenna based on a thin film bulk acoustic wave resonator structure according to claim 7, characterized in that: The lower electrode layer and the upper electrode layer are respectively composed of one or more materials selected from aluminum, gold, molybdenum, chromium, and titanium, and have a thickness of 10 nm to 2 μm.

10. The micro piezoelectric antenna based on a thin film bulk acoustic wave resonator structure according to claim 7, characterized in that: The insulating passivation layer is made of materials such as aluminum nitride, scandium-doped aluminum nitride, aluminum oxide, silicon oxide, etc., and is used to protect the upper electrode layer during the process, with a thickness of 10nm-2μm.

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