A micro piezoelectric antenna based on a thin film bulk acoustic resonator structure

Abstract

The present invention provides a micro-piezoelectric antenna based on a thin film bulk acoustic wave resonator (FBAR) structure. The antenna comprises, from bottom to top, a FBAR, an insulating passivation layer, and a second piezoelectric layer. The FBAR structure generates and transmits acoustic waves to the second piezoelectric layer, and also receives acoustic waves from the second piezoelectric layer and generates corresponding electrical signals. The second piezoelectric layer, under the excitation of received acoustic waves, causes standing waves within the second piezoelectric layer along the thickness direction to be in phase, or largely in phase, thereby radiating electromagnetic waves outward. The antenna also receives external electromagnetic waves and, under the action of the electromagnetic wave's electric field component, generates acoustic waves, which are then transmitted to the FBAR. This micro-piezoelectric antenna is compact, capable of multi-frequency resonance, and significantly improves the radiation efficiency of piezoelectric materials. It represents a future solution for the miniaturization of wireless communication systems.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro-nanoelectronics and microwave communications, and in particular 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 growing. However, the size and energy consumption of traditional antennas in these applications limit the overall performance of the system. This problem is particularly prominent in environments with extremely stringent requirements on size and power consumption.

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

[0004] Patent application CN109103582A discloses a nanomechanical acoustic antenna with a thin film bulk acoustic resonator structure and its manufacturing method. The antenna comprises a substrate, a magnetostrictive layer, and a piezoelectric stack. The piezoelectric stack includes a piezoelectric film, a lower electrode, and an upper electrode. The lower electrode is positioned between the piezoelectric film and the substrate, while the magnetostrictive layer and the upper electrode are positioned above the piezoelectric film. A through-hole is provided in the substrate at the location of the lower electrode for electrical connection to the lower electrode. The antenna disclosed in this patent application is smaller in size and has a simple and reliable manufacturing process. The piezoelectric layer primarily deforms in response to voltage changes, thereby generating acoustic waves. Under acoustic excitation, the magnetostrictive layer generates an oscillating magnetic current due to the inverse magnetostrictive effect, resulting in the generation of corresponding electromagnetic waves. However, the performance and size of the antenna provided by this patent are limited by the magnetostrictive material, making further improvement difficult.

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

[0006] Unlike traditional electric antennas, micro-acoustically actuated antennas utilize the coupling mechanism of acoustic and electromagnetic waves to achieve signal reception and transmission, thus demonstrating greater adaptability in complex transmission environments. Currently, mainstream acoustically actuated micro-antennas typically use magnetostrictive materials as the radiating layer. Their performance is limited by the inherent losses of the magnetostrictive materials and the manufacturing process. Furthermore, the manufacturing difficulty of micro-antennas is relatively high, which affects their practicality and widespread application.

[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, have extremely low radiation efficiency, and are difficult to achieve further miniaturization. Summary of the Invention

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

[0009] The present invention provides a micro piezoelectric antenna based on a thin film bulk acoustic wave resonator structure, which includes, from bottom to top, a thin film bulk acoustic wave resonator structure and a second piezoelectric layer:

[0010] 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 sound waves from the second piezoelectric layer and generate corresponding electrical signals;

[0011] The second piezoelectric layer is used to make the standing waves inside the second piezoelectric layer along the thickness direction be in the same phase or most of them be in the same phase under the excitation of the received sound waves, that is, to make more than 70% of the sound waves in the part where the standing waves are distributed in the second piezoelectric layer be in the same phase, 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 resonator structure.

[0012] Preferably, the FBAR structure includes a first piezoelectric layer, and the thickness of the first piezoelectric layer and the second piezoelectric layer are respectively 100 nm-10 μm.

[0013] The present invention sets appropriate thicknesses of the first piezoelectric layer and the second piezoelectric layer, and aims to ensure that the standing waves along the thickness direction inside the second piezoelectric layer are in the same phase or are mostly in the same phase under the excitation of acoustic waves. By modeling and calculating the set antenna through multi-physics field simulation software, the operating frequency of the antenna and the geometric parameters of each layer of the antenna can be obtained.

[0014] Further preferably, multi-physics field simulation software is used 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. The optimization goal is that the second piezoelectric layer is excited by the received sound wave so that the standing waves along the thickness direction inside the second piezoelectric layer are in the same phase or most of them are in the same phase, thereby obtaining the operating frequency of the antenna provided by the present invention and the geometric parameters of the antenna provided by the present invention.

[0015] Preferably, the second piezoelectric layer is composed of an alloy or a multilayer structure of one or more piezoelectric materials selected from aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lithium niobate, and lead zirconate titanate.

[0016] Further preferably, 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.

[0017] The further preferred material provided by the present invention has lower mechanical loss and electrical hysteresis loss. Due to the lower mechanical loss, the conversion efficiency of the acoustic wave can be improved during the electrical-acoustic wave conversion process. Due to the lower electrical hysteresis loss, the efficiency of the acoustic wave-polarization conversion can be improved, thereby improving the radiation capacity of the second piezoelectric layer.

[0018] Preferably, the lateral dimension of the second piezoelectric layer is 20 μm-1000 μm.

[0019] Preferably, the thin film bulk acoustic resonator structure includes a cavity type FBAR, a back-etched type FBAR, a solid assembly type FBAR or an HBAR structure.

[0020] The FBAR structure is a cavity-type FBAR, where the cavity is formed by providing a sacrificial layer and releasing the sacrificial layer through dry or wet etching; or the FBAR structure is a back-etched FBAR, where the cavity is formed by back-etching the substrate; or the FBAR structure is a solid-body FBAR, where the cavity is formed by depositing a Bragg reflector layer on the substrate. The piezoelectric antennas based on the cavity-type FBAR, back-etched FBAR, and solid-body FBAR structures can operate in first and second-order resonant modes. Alternatively, the antenna can operate in a high-overtone bulk acoustic wave mode, or HBAR mode, by retaining a sacrificial layer in the cavity region, or by directly depositing the FBAR structure on the substrate without creating a cavity.

[0021] Preferably, 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;

[0022] 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-engraved inside the substrate to the seed layer.

[0023] Further preferably, 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 5 nm-200 nm.

[0024] The insulating passivation layer provided in the specific embodiment of the present invention is used to protect the metal of the upper electrode layer and to adjust the resonant frequency of the antenna.

[0025] Further preferably, 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.

[0026] Preferably, the insulating passivation layer is made of aluminum nitride, scandium-doped aluminum nitride, aluminum oxide, silicon oxide and other materials and is used to protect the upper electrode layer during the process, with a thickness of 10 nm-2 μm.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention utilizes the acoustic wave excitation effect generated by the thin film bulk acoustic resonator (FBAR) structure for the first time to make the standing waves along the thickness direction inside the second piezoelectric layer be in the same phase or mostly in the same phase, so that the polarization rotation synchronized with the frequency of the acoustic wave inside is also in the same phase or mostly in the same phase, thereby making the internal electric dipole oscillation radiate, and realizing the antenna to radiate electromagnetic waves outward.

[0029] Since the wavelength of sound waves is 4-5 orders of magnitude smaller than the wavelength of electromagnetic waves of the same frequency, the overall size of the antenna provided in this application must match the wavelength of the sound waves. Compared with the antennas disclosed in the prior art that match the wavelength of electromagnetic waves, the size is smaller, breaking through the size limitations of traditional antennas and realizing a micron-level miniaturized design.

[0030] With the help of the resonant characteristics of FBAR, the antenna provided by the present invention can operate in the millimeter wave and even submillimeter wave frequency bands, and is suitable for high-frequency communication and sensing fields. Compared with the magnetostrictive-piezoelectric structure of the magnetoelectric antenna, the antenna obtained by the FBAR structure and the second piezoelectric layer design provided by the present invention utilizes the electromechanical coupling between the two piezoelectric layers to improve the sound-to-electric conversion efficiency, enhance the electromagnetic radiation capability and overall performance of the antenna, and the antenna provided by the present invention can operate in the range of 2-4GHz.

[0031] In addition, the antenna structure is compatible with existing CMOS and MEMS manufacturing processes, which helps to achieve large-scale mass production and has broad application prospects in future wireless communications, wearable medical care, microsensors and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic structural diagram of a micro piezoelectric acoustically actuated antenna based on a thin film bulk acoustic resonator according to a specific embodiment of the present invention, wherein the sacrificial layer material in the cavity 101 is released, and the cavity is filled with air, forming a suspended structure;

[0033] Figure 2 A schematic structural diagram of a micro piezoelectric acoustically actuated antenna based on a thin film bulk acoustic resonator is provided in a specific embodiment of the present invention, wherein a patterned sacrificial layer material is deposited on a substrate 100 and a cavity 101 is formed by releasing the sacrificial layer.

[0034] Figure 3 A schematic structural diagram of a micro piezoelectric acoustically actuated antenna based on a thin film bulk acoustic resonator according to a specific embodiment of the present invention, wherein the cavity 101 is formed by back-etching the substrate 100 to form a back-etched FBAR structure;

[0035] Figure 4 A schematic structural diagram of a micro piezoelectric acoustically actuated antenna based on a thin film bulk acoustic resonator provided in a specific embodiment of the present invention, wherein region 101 is composed of Bragg reflection layer material;

[0036] Figure 5 A schematic structural diagram of a micro piezoelectric acoustically actuated antenna based on a thin film bulk acoustic resonator according to a specific embodiment of the present invention, wherein the sacrificial layer material in the cavity 101 is retained to form an HBAR structure;

[0037] Figure 6 A schematic structural diagram of a micro piezoelectric acoustically actuated antenna based on a thin film bulk acoustic resonator according to a specific embodiment of the present invention, wherein the cavity 101 region is not formed, and thin films 102-107 are directly deposited on a substrate 100 to form an HBAR structure;

[0038] Figure 7 Schematic diagram of a performance testing system for a micro piezoelectric antenna provided in a specific embodiment of the present invention;

[0039] Figure 8 The specific embodiment of the present invention provides Figure 1 The performance test results of the micro piezoelectric antenna based on the cavity FBAR in the first-order resonant mode are shown, including S 22 , S 21 and S 12 Parameter testing;

[0040] Figure 9 The specific embodiment of the present invention provides Figure 1 The performance test results of the micro piezoelectric antenna based on the cavity FBAR in the second-order resonant mode are shown, including S 22 , S 21 and S 12 Parameter testing;

[0041] Figure 10 The specific embodiment of the present invention provides Figure 4 The performance test results of the HBAR-based micro piezoelectric antenna in its multiple resonant modes, including S 22 , S 21 and S 12 Parameter testing;

[0042] Among them, 100 is a substrate layer, 101 is a cavity, 102 is a seed layer, 103 is a lower electrode layer, 104 is a first piezoelectric layer, 105 is an upper electrode layer, 106 is an insulating passivation layer, and 107 is a second piezoelectric layer. DETAILED DESCRIPTION

[0043] The present invention provides a micro piezoelectric acoustically actuated antenna based on a thin film bulk acoustic resonator, comprising 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, thereby miniaturizing the antenna and improving the radiation efficiency of the antenna, ultimately obtaining a new type of micro antenna.

[0044] A specific embodiment of the present invention provides a micro piezoelectric antenna based on a thin film bulk acoustic wave structure, which includes, from bottom to top, a thin film bulk acoustic wave resonator structure and a second piezoelectric layer:

[0045] The thin film bulk acoustic wave resonator structure provided in a specific embodiment of the present invention is used to generate sound waves and transmit the sound waves to the second piezoelectric layer, and is also used to receive sound waves from the second piezoelectric layer and generate corresponding electrical signals;

[0046] The second piezoelectric layer provided in a specific embodiment of the present invention is used to make the standing waves 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 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 resonator.

[0047] Specific embodiments of the present invention propose a micro piezoelectric antenna based on an FBAR structure. During transmission, the antenna utilizes the FBAR structure to generate acoustic waves and drive the piezoelectric material to vibrate. Upon being excited by the acoustic waves, the piezoelectric material undergoes internal polarization rotation synchronized with the acoustic waves due to the piezoelectric effect, radiating outward. During reception, the antenna receives electromagnetic waves, and the piezoelectric material, under the influence of the electromagnetic wave's electric field component, generates acoustic waves. These waves enter the FBAR structure and are converted into electrical signals on the upper and lower electrodes, achieving efficient radiation and reception of electromagnetic waves. Leveraging the resonant properties of the FBAR structure, the antenna not only enables efficient miniaturization but also has the potential to expand into higher frequency bands such as millimeter and submillimeter waves, thereby meeting the demand for compact, high-frequency, low-power antennas in complex environments. This technology has broad application prospects in wearable electronics, implantable medical devices, portable smart terminals, and other fields, providing new ideas and technical foundations for the research and application of next-generation high-performance micro antennas.

[0048] The antenna provided by the specific embodiment of the present invention is further described below with reference to specific examples. Figure 1 A schematic structural diagram of a micro piezoelectric acoustically actuated antenna based on a thin film bulk acoustic resonator provided by the present invention; from bottom to top, it 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 constitute 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.

[0049] A manufacturing method of the present invention comprises the following specific steps:

[0050] 1) An insulating substrate 100 is placed in acetone, isopropyl alcohol and deionized water for ultrasonic cleaning, and a cavity 101 is etched in the substrate using an RIE or ICP etching process with a depth of 3 μm.

[0051] 2) 3μm-5μm phosphosilicate glass (PSG) is deposited on the substrate 100 as a sacrificial layer material by a process such as chemical vapor deposition (CVD) or physical vapor deposition (PVD). Then, excess PSG material is removed by a chemical mechanical polishing process (CMP), leaving only the sacrificial layer in the cavity 101.

[0052] 3) A 30 nm aluminum nitride seed layer 102 and a 100 nm molybdenum layer are deposited on the substrate as the lower electrode layer 103 by CVD or magnetron sputtering, and the seed layer 102 and the lower electrode layer 103 are patterned by ICP etching or photolithography-stripping process.

[0053] 4) A 350 nm thick c-axis oriented scandium-doped aluminum nitride film is deposited as the first piezoelectric layer 104 by magnetron sputtering, CVD, thermal evaporation or other processes, and the first piezoelectric layer 104 is patterned by ICP etching or photolithography-lift-off process.

[0054] 5) A 150nm molybdenum top electrode layer 105 and a 120nm aluminum nitride insulating passivation layer 106 are deposited on the first piezoelectric layer 104 by CVD or magnetron sputtering, and the top electrode layer 105 and the insulating passivation layer 106 are patterned by ICP etching or photolithography-stripping process.

[0055] 6) Using hydrofluoric acid wet etching or other methods to release the sacrificial layer to form a cavity 101.

[0056] 7) A c-axis oriented zinc oxide film with a thickness of 850 nm is deposited on the insulating passivation layer 106 by magnetron sputtering as the second piezoelectric layer 107 , and a patterned second piezoelectric layer 107 is formed by ICP etching or photolithography-lift-off process.

[0057] The substrate 100 provided in this embodiment of the present invention can be made of one or a combination of silicon, silicon oxide, sapphire, silicon carbide, glass, quartz, etc. The cavity 101 structure is formed by wet etching, dry etching methods such as ICP and RIE. The cavity pattern can be any shape, such as a triangle, quadrilateral, pentagon, or circle, with a lateral dimension of 20 μm to 1000 μm and a thickness of 500 nm to 10 μm.

[0058] The seed layer 102 provided in a specific embodiment of the present invention is made of materials such as aluminum nitride and is used to improve the film deposition quality of the lower electrode layer 103, with a thickness of 5nm-200nm.

[0059] The lower electrode layer 103 provided in the embodiment of the present invention is composed of one or more materials selected from aluminum, gold, molybdenum, chromium, titanium, etc., and has a thickness of 10nm-2μm. The lower electrode layer 103 can be patterned by processes such as stripping, dry etching, and wet etching.

[0060] The first piezoelectric layer 104 provided in a specific embodiment of the present invention is composed of one or more piezoelectric materials such as aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lead zirconate titanate, and lithium niobate. The thickness of the first piezoelectric layer is 100 nm-10 μm.

[0061] The upper electrode layer 105 provided in the embodiment of the present invention is composed of one or more materials selected from aluminum, gold, molybdenum, chromium, titanium, etc., and has a thickness of 10nm-2μm. The upper electrode layer 105 can be patterned by processes such as stripping, dry etching, and wet etching.

[0062] The insulating passivation layer 106 provided in a specific embodiment of the present invention is a combination of one or more materials selected from aluminum nitride, scandium-doped aluminum nitride, aluminum oxide, silicon oxide, and the like.

[0063] The second piezoelectric layer 107 provided in the specific embodiment of the present invention is composed of one or more piezoelectric materials such as aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lithium niobate, etc., and is patterned by processes such as stripping, dry etching, and wet etching. The thickness of the second piezoelectric layer is 100nm-10μm.

[0064] The above example is an example of the FBAR structure of the present invention being a cavity type FBAR, that is, the cavity is formed by setting a sacrificial layer and releasing the sacrificial layer by dry or wet etching to form a cavity suspended structure. Figure 1 and Figure 2 shown.

[0065] The present invention provides a method for back etching the substrate 100 to form a cavity 101. Figure 3 As shown, a back-etched FBAR structure can be formed; in addition, a solid-state assembly (SMR) type FBAR is constructed by providing a Bragg reflection layer on the substrate 100, as shown in FIG. Figure 4 As shown; FBAR can also be made to work in high-mode bulk acoustic wave mode (HBAR) by retaining a sacrificial layer in the cavity, as shown Figure 5 As shown; the HBAR structure can also be formed by omitting the processing technology of the region 101 and directly depositing the thin film layers 102-107 on the substrate 100, as shown Figure 6 Regardless of which structure is used, the antenna according to the present invention can drive the piezoelectric material at the resonant frequency of the corresponding structure to complete the function of transmitting and receiving electromagnetic radiation, thereby constructing a new type of micro piezoelectric antenna.

[0066] The schematic diagram of a test system for a micro piezoelectric acoustically actuated antenna based on a cavity-type FBAR described in this example is shown in FIG. Figure 7 As shown in Figure 1, this test system measures the gain of a piezoelectric antenna using the gain comparison method. During testing, port 1 of the vector network analyzer is connected to an external receiving antenna with nominal gain, while port 2 is connected to the miniature piezoelectric acoustically actuated antenna described in this invention. The system also records the return loss curve (S) of the piezoelectric antenna. 22 ) and the transmission coefficient curve between the transmitting antenna and the receiving antenna (S 21 and S 12 ). Among them, S22 The curve reflects the ratio of the energy of the incident signal to the energy of the reflected signal. There will be an obvious peak near the antenna resonant frequency, indicating that the antenna is working in this mode. 21 and S 12 The curve represents the ratio of the signal transmitted by the transmitting antenna to that transmitted by the receiving antenna, S 12 and S 21 The overlap of the curves indicates that the test system network has reciprocity. 21 (or S 12 ) curve in S 22 When the maximum rising peak is formed at the peak value, it indicates that the radiation signal of the tested piezoelectric antenna is the strongest at this frequency, that is, this frequency is the working center frequency of the antenna.

[0067] The performance of the first-order resonance mode and the second-order resonance mode provided by the specific embodiment of the present invention are as follows: Figure 8 and Figure 9 As shown, the antenna is at the resonant frequency, i.e. S 22 At the peak frequency, the transmission coefficient S 21 / S 12 reaches the maximum value, indicating that the intensity of the electromagnetic signal radiated and received by the piezoelectric antenna at this frequency reaches the highest, that is, the antenna works within this frequency band; Figure 10 As shown, the HBAR-based micro piezoelectric acoustically actuated antenna described in this example can operate in multiple high-order resonance modes, thereby widening the antenna's operating frequency band.

[0068] like Figure 8 As shown, S 22 The peak of the curve is at 1.85GHz, that is, the first-order thickness resonant frequency of the antenna is 1.85GHz, and the corresponding S 12 and S 21 The curve also reaches a maximum value at 1.85 GHz, indicating that the operating center frequency of the piezoelectric antenna is 1.85 GHz.

[0069] like Figure 9 As shown, S 22 The peak of the curve is at 3.92GHz, that is, the second-order thickness resonance frequency of the antenna is 3.91GHz, and the corresponding S 12 and S 21 The curve also reaches a maximum value at 3.91 GHz, indicating that the operating center frequency of the piezoelectric antenna is 3.92 GHz.

[0070] like Figure 10 As shown, S 22 The peak envelope of the curve reaches its peak in the frequency band near 2GHz, that is, the resonance characteristics of the 12-15 high-order resonance modes of the piezoelectric antenna based on the HBAR structure are most obvious in the frequency band near 2GHz, and the corresponding S 12 and S 21The curve is also in the inner S of the frequency band near 2GHz 22 It reaches the maximum value at each peak point, indicating that the piezoelectric antenna operates in 12-15 high-order resonant frequency bands near the 2 GHz frequency band.

[0071] The above contents are only preferred embodiments of the present invention and do 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 intended to limit its scope of application. For those skilled in the art, without departing from the technical solution of the present invention, certain adjustments or improvements are made based on the technical contents disclosed in this specification to form functionally equivalent variant implementation plans, which should be regarded as belonging to the technical scope of the present invention. Any simple modification, equivalent replacement or adjustment of the above implementation plans based on the technical essence of the present invention still falls within the scope of protection of the present invention.

Claims

1. A micro piezoelectric antenna based on a thin film bulk acoustic resonator structure, characterized in that: From bottom to top, it includes the thin film bulk acoustic 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 sound waves from the second piezoelectric layer and generate corresponding electrical signals; The second piezoelectric layer is configured to, under the excitation of received sound waves, cause standing waves along the thickness direction of the second piezoelectric layer to be in the same phase during resonance, or cause more than 70% of the sound waves distributed in the second piezoelectric layer to be in the same phase. Under the action of the piezoelectric effect, the second piezoelectric layer will undergo synchronous polarization rotation with the sound waves, thereby radiating electromagnetic waves outward. The second piezoelectric layer is further configured 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 resonator structure. 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.

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

3. The micro piezoelectric antenna based on a thin film bulk acoustic 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 piezoelectric materials selected from aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lithium niobate, and lead zirconate titanate.

4. The micro piezoelectric antenna based on a thin film bulk acoustic resonator structure according to claim 3, 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 resonator structure according to claim 1, characterized in that: The lateral size of the second piezoelectric layer is 20 μm-1000 μm.

6. The micro piezoelectric antenna based on a thin film bulk acoustic 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.

7. The micro piezoelectric antenna based on a thin film bulk acoustic resonator structure according to claim 6, 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.

8. The micro piezoelectric antenna based on a thin film bulk acoustic resonator structure according to claim 6, 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.

9. The micro piezoelectric antenna based on a thin film bulk acoustic resonator structure according to claim 6, 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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