A micro-displacement detection device based on frequency drift of bulk acoustic wave resonator

Abstract

The application discloses a kind of micro displacement detection devices based on bulk acoustic resonator frequency drift, comprising: displacement conduction module and displacement detection module;Wherein, displacement detection module includes: cantilever beam, one end of cantilever beam is fixed end, the other end is free end;Bulk acoustic resonator is arranged between fixed end and free end of cantilever beam;Displacement conversion structure is fixed in the free end of cantilever beam;When displacement conduction module moves, displacement conversion structure can drive cantilever beam to occur bending deformation under the pushing of displacement conduction module, to change the stress state of bulk acoustic resonator, make its resonant frequency drift.The technical scheme provided by the application keeps low power consumption, high integration, eliminates friction and interference caused by contact measurement, and improves the detection accuracy of micro displacement.

Description

Technical Field

[0001] This invention relates to the field of micro-displacement detection technology, and in particular to a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator. Background Technology

[0002] Micro-displacement detection technology has wide applications in precision manufacturing, semiconductor processing, biomedical engineering, and high-end consumer electronics. With the continuous improvement of system integration, higher demands are being placed on the size, power consumption, environmental adaptability, and cost of micro-displacement sensors. Traditional high-performance displacement sensors, such as laser interferometers, while possessing extremely high accuracy, are bulky, expensive, and consume a lot of power, making them difficult to integrate into portable or space-constrained systems. While some integrable microelectromechanical system (MEMS) sensors, such as capacitive and piezoresistive sensors, have advantages in miniaturization, they generally suffer from temperature drift issues in practical applications, and are mostly active detection methods, increasing system power consumption and signal processing complexity, making it difficult to meet the application requirements of high stability and low power consumption.

[0003] To overcome the aforementioned problems, passive sensing technology based on acoustic resonators has emerged in recent years. This approach uses a lead shaft to drive the axial movement of a pressing block, allowing the pressing block to directly contact different positions on the HBAR micro-displacement detector body. By changing the thickness or equivalent thickness of the piezoelectric element, a change in the resonant frequency is induced, thereby achieving displacement detection. This approach utilizes the passive characteristics of HBARs, reducing detection power consumption to some extent, and has the potential to be compatible with MEMS processes.

[0004] However, since its detection principle relies on direct contact between the extrusion block and the HBAR detector body, and changes the physical or equivalent thickness of the piezoelectric element through extrusion, it belongs to a contact measurement method. In practical applications, contact measurement may introduce mechanical friction, wear under long-term use, and interference from external stimuli, affecting the sensor's detection accuracy. Therefore, how to eliminate the friction and interference caused by contact measurement while maintaining low power consumption and high integration, and improve the detection accuracy of micro-displacements, is a technical problem that urgently needs to be solved by those in the field. Summary of the Invention

[0005] This invention provides a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator. While maintaining low power consumption and high integration, it eliminates friction and interference caused by contact measurement and improves the detection accuracy of micro-displacements.

[0006] This invention provides a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator, comprising: a displacement transmission module and a displacement detection module; wherein, the displacement detection module includes: A cantilever beam, wherein one end of the cantilever beam is a fixed end and the other end is a free end; A bulk acoustic resonator is disposed between the fixed end and the free end of the cantilever beam; The displacement conversion structure is fixed to the free end of the cantilever beam; When the displacement transmission module moves, the displacement conversion structure can drive the cantilever beam to bend and deform under the push of the displacement transmission module, thereby changing the stress state of the bulk acoustic resonator and causing its resonant frequency to drift.

[0007] Optionally, the micro-displacement detection device based on the frequency drift of a bulk acoustic resonator further includes: A frequency detection module is electrically connected to the bulk acoustic wave resonator; the frequency detection module is used to detect the resonant frequency drift of the bulk acoustic wave resonator and output the displacement according to a preset frequency drift-displacement mapping relationship.

[0008] Optionally, the displacement conversion structure has an inclined surface, and the displacement transmission module is in contact with the inclined surface of the displacement conversion structure; When the displacement transmission module moves, it slides along the inclined surface of the displacement conversion structure, driving the cantilever beam to bend and deform.

[0009] Optionally, the displacement transmission module includes a displacement rod and a displacement force application component, wherein the displacement force application component is disposed on the circumferential sidewall at one end of the displacement rod; When the displacement rod moves, the displacement force-applying component slides along the inclined surface of the displacement conversion structure, driving the cantilever beam to bend and deform.

[0010] Optionally, the inclined surface of the displacement conversion structure is a plane; The end of the displacement force-applying component that contacts the displacement conversion structure is a spherical surface.

[0011] Optionally, the displacement transmission module and the bulk acoustic resonator are located on the same surface of the cantilever beam.

[0012] Optionally, the bulk acoustic resonator includes a substrate, a bottom electrode, a piezoelectric layer, and a top electrode stacked sequentially. The bulk acoustic resonance also includes a first external electrode electrically connected to the bottom electrode and a second external electrode electrically connected to the top electrode.

[0013] Optionally, the cantilever beam can be reused as the base.

[0014] Optionally, the bulk acoustic resonator is a thin-film bulk acoustic resonator.

[0015] Optionally, the bulk acoustic resonator is a high-order harmonic bulk acoustic resonator.

[0016] The technical solution provided by this invention involves placing a bulk acoustic wave resonator on a flexible cantilever beam and setting a displacement conversion structure at the free end of the cantilever beam. When the displacement transmission module undergoes displacement, it can compress the displacement conversion structure, causing the cantilever beam to bend and deform. This, in turn, causes strain in the bulk acoustic wave resonator on the cantilever beam, resulting in a drift in its characteristic frequency, thus quantifying the displacement. In other words, through the correlation link of micro-displacement-structural bending-bulk acoustic wave resonator frequency drift, the quantitative detection of micro-displacement is achieved, fundamentally avoiding friction and interference to the bulk acoustic wave resonator. The bulk acoustic wave resonator has passive characteristics, ensuring extremely low power consumption. Therefore, this invention, while maintaining low power consumption and high integration, eliminates the friction and interference caused by contact measurement, improving the detection accuracy of micro-displacement.

[0017] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a displacement detection module provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of another displacement detection module provided in an embodiment of the present invention; Figure 3 This is a flowchart illustrating the operation of a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator, as provided in an embodiment of the present invention. Figure 4 This is a flowchart of another micro-displacement detection device based on the frequency drift of a bulk acoustic resonator provided in an embodiment of the present invention; Figure 5 This is a schematic cross-sectional view of step S10 in the fabrication method of a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator provided in an embodiment of the present invention. Figure 6 This is a schematic cross-sectional view of step S20 in the fabrication method of a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator provided in an embodiment of the present invention. Figure 7This is a schematic cross-sectional view of step S30 in the fabrication method of a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator provided in an embodiment of the present invention. Figure 8 This is a schematic cross-sectional view of step S40 in the fabrication method of a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator provided in an embodiment of the present invention. Figure 9 This is a schematic cross-sectional view of step S50 in the fabrication method of a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator provided in an embodiment of the present invention. Figure 10 This is a schematic cross-sectional view of step S60 in the fabrication method of a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator provided in an embodiment of the present invention. Figure 11 This is a schematic cross-sectional view of step S70 in the fabrication method of a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator provided in an embodiment of the present invention. Figure 12 This is a schematic cross-sectional view of step S61 in the fabrication method of a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator provided in an embodiment of the present invention. Figure 13 This is a cross-sectional structural diagram corresponding to step S70 in the preparation method of another micro-displacement detection device based on the frequency drift of a bulk acoustic resonator provided in an embodiment of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0022] This invention provides a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator, comprising: a displacement transmission module and a displacement detection module; Figure 1 This is a schematic diagram of the structure of a displacement detection module provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of another displacement detection module provided in an embodiment of the present invention, for reference. Figure 1 and Figure 2 In the micro-displacement detection device, the displacement detection module 100 includes: Cantilever beam 10, one end of which is fixed end A, and the other end is free end B; A bulk acoustic resonator is installed between the fixed end A and the free end B of the cantilever beam 10; The displacement conversion structure 20 is fixed to the free end B of the cantilever beam 10; When the displacement transmission module moves, the displacement conversion structure 20 can drive the cantilever beam 10 to bend and deform under the push of the displacement transmission module, so as to change the stress state of the bulk acoustic resonator and cause its resonant frequency to drift.

[0023] The technical solution provided by this invention involves placing a bulk acoustic wave resonator on a flexible cantilever beam 10 and setting a displacement conversion structure 20 at the free end B of the cantilever beam 10. When the displacement transmission module undergoes displacement, it can compress the displacement conversion structure 20, causing the cantilever beam 10 to bend and deform. This, in turn, causes strain in the bulk acoustic wave resonator on the cantilever beam 10, resulting in a drift in its characteristic frequency, thus quantifying the displacement. In other words, the quantitative detection of micro-displacement is achieved through the correlation link of micro-displacement, structural bending, and bulk acoustic wave resonator frequency drift, fundamentally avoiding friction on the bulk acoustic wave resonator. The bulk acoustic wave resonator has passive characteristics, ensuring extremely low power consumption. Therefore, this embodiment of the invention maintains the low power consumption and high integration of the micro-displacement detection device while eliminating friction and interference caused by contact measurement, improving the detection accuracy of micro-displacement.

[0024] The above are the core inventive points of this invention. The structure of the micro-displacement detection device based on the frequency drift of a bulk acoustic resonator will be described in detail below with reference to the accompanying drawings.

[0025] refer to Figure 1 The bulk acoustic resonator can be a film bulk acoustic resonator (FBAR). (See reference...) Figure 2Bulk acoustic resonators can also be classified as high-overtone bulk acoustic resonators (HBARs). Both belong to the category of bulk acoustic resonators, and their basic principle utilizes the inverse piezoelectric effect of piezoelectric materials to achieve frequency selection through acoustic wave resonance. Both FBARs and HBARs are passive, ensuring long-term measurement stability and extremely low power consumption in passive environments. Their miniaturized structure allows them to be embedded in various microsystems.

[0026] Both the thin-film bulk acoustic resonator (FBAR) and the high-harmonic bulk acoustic resonator (HBAR) include a substrate 34, a bottom electrode 31, a piezoelectric layer 33, and a top electrode 32, which are stacked sequentially. They also include a first external electrode 311 electrically connected to the bottom electrode 31 and a second external electrode 321 electrically connected to the top electrode 32. The FBAR uses a thin-film structure, and its resonant frequency is mainly determined by the thickness of the piezoelectric layer. The HBAR, on the other hand, typically consists of a thicker substrate 34 and a piezoelectric layer 33, capable of exciting high-harmonic waves and possessing a higher quality factor (Q value). Using the HBAR avoids the problem of insufficient structural strength caused by back etching, thus meeting the requirements of some wide measurement ranges.

[0027] The cantilever beam 10 is a beam structure with one end fixed and the other end free. The fixed end A of the cantilever beam 10 can be fixedly connected to a base or a shell; this invention does not limit this. The material of the cantilever beam 10 can include semiconductor materials, organic materials, or metallic materials. For example, the cantilever beam 10 can be made of silicon-based materials. Specifically, the cantilever beam 10 can be composed of one or more combinations of single-crystal silicon, polycrystalline silicon, or silicon nitride. Silicon-based materials have excellent mechanical strength, high elastic modulus, and high compatibility with MEMS processes, enabling precision machining at the micron or even nanometer scale, making them suitable for highly integrated, mass-produced microsystems. Alternatively, the cantilever beam 10 can be made of metallic materials. Specifically, the cantilever beam 10 can be composed of one or more combinations of molybdenum, aluminum, nickel, copper, or their alloys. Optionally, when the material of the cantilever beam 10 is silicon, the cantilever beam 10 can be reused as the substrate 34 in a bulk acoustic resonator, thereby facilitating the miniaturization of the micro-displacement detection device.

[0028] Figure 3 This is a flowchart illustrating the operation of a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator provided by the present invention. The device consists of... Figure 1 The displacement detection module 100 and the displacement transmission module 200 shown are combined. Figure 4 This is a flowchart illustrating the operation of another micro-displacement detection device based on the frequency drift of a bulk acoustic resonator provided by the present invention. The device consists of... Figure 2 The displacement detection module 100 and displacement transmission module 200 shown are combined. (Reference) Figure 3 and Figure 4The micro-displacement detection device provided in this embodiment works as follows: When the displacement source to be measured generates displacement, it drives the displacement transmission module 200 to move. The end of the displacement transmission module 200 squeezes the displacement conversion structure 20, thereby converting the displacement of the displacement transmission module 200 into a driving force for the cantilever beam 10 to bend and deform. When the cantilever beam 10 bends and deforms, stress is formed inside the bulk acoustic resonator installed on it, and the stress state of the bulk acoustic resonator changes with the degree of bending of the cantilever beam 10. Stress can be understood as the force per unit area inside an object, and it is a measure of the strength of the object's resistance to external loads. Strain can be understood as the relative deformation of an object under the action of force (stress), and it is a dimensionless measure of the degree of deformation of the object. Therefore, the bending and deforming cantilever beam 10' can drive the bulk acoustic resonator installed on it to generate strain. Strain affects the elastic constant of the material—when the material is subjected to strain, the interatomic distance and bond angle change slightly, changing the interatomic interaction potential energy, which is macroscopically manifested as a change in the elastic constant. The change in the elastic constant further affects the propagation speed of sound waves in the bulk acoustic resonator.

[0029] According to the formula for the speed of sound v = ,in C It is the elastic constant, or the elastic modulus of a material, commonly used (Using a fourth-order tensor) to represent, It refers to the density of the material and the speed of sound. v With elastic constant C The frequency of a bulk acoustic resonator changes with the speed of sound. Ultimately, the change in the speed of sound determines the characteristic frequency of the bulk acoustic resonator. For a thin-film bulk acoustic resonator, its resonant frequency approximately satisfies the following condition: ,in v For the speed of sound, h This is the equivalent thickness of the piezoelectric layer. When the speed of sound... v When it changes, the resonant frequency f 0 produces a corresponding drift. Since there is a good linear relationship between the curvature of the cantilever beam 10 and the frequency drift of the bulk acoustic resonator, and the displacement is linearly related to the curvature, the displacement can be accurately measured by detecting the drift of the characteristic frequency.

[0030] Based on the above embodiments, optionally, the micro-displacement detection device based on the frequency drift of a bulk acoustic resonator further includes: The frequency detection module is electrically connected to the bulk acoustic wave resonator. The frequency detection module is used to detect the resonant frequency drift of the bulk acoustic wave resonator and output the displacement according to the frequency drift-displacement mapping relationship.

[0031] Specifically, a vector network analyzer can be used to detect the characteristic frequency of the bulk acoustic wave resonator. The input and output terminals of the bulk acoustic wave resonator are connected to the test ports of the vector network analyzer; the detected real-time characteristic frequency is compared with a reference frequency to obtain the frequency drift. The displacement can then be output according to a preset frequency drift-displacement mapping relationship.

[0032] Optionally, the determination of the frequency drift-displacement mapping relationship may include: when the cantilever beam 10 is under different degrees of bending, continuously recording the changes in characteristic frequencies through a vector network analyzer, thereby establishing the frequency drift-displacement mapping relationship and providing a basis for back-calculation in subsequent practical applications.

[0033] In practical product applications, to meet the requirements of miniaturization, low power consumption, low cost, and real-time detection, integrated scanning circuits can be used to replace vector network analyzers. That is, the frequency detection module can also be an integrated scanning circuit. The scanning circuit can be integrated inside the driver chip and is essentially a signal generation and analysis circuit, specifically including: a sweep frequency signal generator, used to generate an excitation signal whose frequency changes continuously or in steps within a certain range; and a power detection unit, used to detect the energy or power of the excitation signal after passing through a bulk acoustic resonator. The power detection unit collects the output signal power after passing through the bulk acoustic resonator in real time, performs energy analysis on the signal after passing through FBAR or HBAR, and can detect the signal with the lowest or highest energy loss at a certain frequency, thereby obtaining the characteristic frequency. The detected real-time characteristic frequency is compared with the reference frequency to obtain the frequency drift.

[0034] Based on the above embodiments, refer to Figures 1-4 Optionally, the displacement conversion structure 20 has an inclined surface a. When the displacement transmission module 200 moves, it slides along the inclined surface a of the displacement conversion structure 20, driving the cantilever beam 10 to undergo bending deformation. It should be noted that when the displacement transmission module 200 is not displaced, it may or may not be in contact with the inclined surface a of the displacement conversion structure 20. In the case of no contact, the displacement amount must be increased by adding the initial distance between the displacement transmission module 200 and the inclined surface a of the displacement conversion structure 20.

[0035] Specifically, when the displacement source under test moves the displacement transmission module 200, the displacement transmission module 200 slides along the inclined plane a of the displacement conversion structure 20, converting the horizontal linear motion into a vertical driving force, which drives the cantilever beam 10 to bend and deform. The inclination angle of the inclined plane a can be designed according to the detection range and accuracy requirements. Different inclination angles of the inclined plane a can produce different degrees of bending for the same displacement, that is, the detection sensitivity of the detection device can be adjusted by changing the inclination angle of the inclined plane a. Different detection requirements can be flexibly matched without changing the structural dimensions of the cantilever beam 10 or the bulk acoustic resonator, thus enhancing the applicability of the device.

[0036] Based on the above embodiments, refer to Figure 3 and Figure 4 Optionally, the displacement transmission module 200 includes a displacement rod 201 and a displacement force application component 202, with the displacement force application component 202 disposed on the circumferential sidewall at one end of the displacement rod 201. When the displacement rod 201 moves, the displacement force application member 202 slides along the inclined plane a of the displacement conversion structure 20, driving the cantilever beam 10 to bend and deform.

[0037] Specifically, when the displacement source to be measured moves the displacement rod 201, the displacement force-applying component 202 on the displacement rod 201 compresses the displacement conversion structure 20, causing the displacement conversion structure 20 to convert the horizontal linear motion of the displacement rod 201 into a vertical driving force on the cantilever beam 10, driving the cantilever beam 10 to bend and deform. During the bending deformation of the cantilever beam 10, the displacement force-applying component 202 slides along the inclined surface a of the displacement conversion structure 20. The displacement force-applying component 202 and the displacement rod 201 can be integrally installed, or the displacement force-applying component 202 can be detachably connected to the displacement rod 201.

[0038] Based on the above embodiments, optionally, the inclined surface a of the displacement conversion structure 20 can be a plane; the end of the displacement force application member 202 that contacts the displacement conversion structure 20 can be a spherical surface.

[0039] Specifically, when the spherical end of the displacement force-applying component 202 contacts the inclined plane a of the displacement conversion structure 20, point contact can be formed between them. Compared with surface contact or line contact, point contact significantly reduces the contact area, thereby greatly reducing frictional resistance and wear during sliding. On the one hand, it reduces the loss of mechanical energy, making displacement transmission more sensitive, and even a small displacement to be measured can cause bending deformation of the cantilever beam 10; on the other hand, it extends the service life of the device, making it particularly suitable for micro-displacement detection scenarios involving long-term reciprocating motion. In addition, setting the inclined plane a of the displacement conversion structure 20 as a plane allows for a linear mapping relationship between the horizontal displacement of the displacement rod 201 and the vertical bending displacement of the free end B of the cantilever beam 10, which simplifies the calibration calculation of the displacement.

[0040] Furthermore, the displacement transmission module 200 and the bulk acoustic resonator are located on the same surface of the cantilever beam 10.

[0041] Specifically, the displacement transmission module 200 (including the displacement rod 201 and the displacement force application component 202) and the bulk acoustic resonator are disposed on the same side surface of the cantilever beam 10. Specifically, the displacement conversion structure 20 is fixed to the upper surface of the free end B of the cantilever beam 10, and the bulk acoustic resonator is also disposed on this upper surface, either adjacent to or opposite to it. When the displacement rod 201 slides along the inclined plane a of the displacement conversion structure 20, the driving force acts directly on the upper surface of the free end B of the cantilever beam 10, causing the cantilever beam 10 to bend. Since the bulk acoustic resonator is also located on the upper surface, it is in the tensile strain region when the cantilever beam 10 bends.

[0042] This invention also provides a method for fabricating a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator, referring to... Figures 5-11 The fabrication method of a micro-displacement detection device based on the frequency drift of a bulk acoustic resonator includes: S10. A substrate 1 is provided, a first conductive layer is formed on a first surface of the substrate 1, and the first conductive layer is patterned to form a bottom electrode 31; wherein the bottom electrode 31 can be made of a metallic material. (Reference) Figure 5 ) S20. A piezoelectric layer 33 is formed on the side of the bottom electrode 31 away from the substrate 1, and the piezoelectric layer 33 is etched to form a first opening 01; the first opening 01 exposes a portion of the bottom electrode 31. (Reference) Figure 6 ) S30. A second conductive layer is formed on the side of the piezoelectric layer 33 away from the substrate 1 and on the sidewall of the first opening 01, and the second conductive layer is etched to electrically isolate the second conductive layer on the sidewall of the first opening 01 from the second conductive layer on the side of the piezoelectric layer 33 away from the substrate 1; wherein, the second conductive layer on the side of the piezoelectric layer 33 away from the substrate 1 forms the top electrode 32. (Reference) Figure 7 ) S40. A second external electrode 321 is formed on the side of the top electrode 32 away from the substrate 1, and a first external electrode 311 is formed in the first opening 01. (Reference) Figure 8 ) S50, A release groove K1 is formed on the first surface of substrate 1. (Reference) Figure 9 ) S60. Etch substrate 1 from its second surface to form cavity Q; wherein, release groove K1 and bottom electrode 31 are located in the region corresponding to cavity Q. (Reference) Figure 10 ) for Figure 2The structure shown includes, after step S60, etching the substrate 1 from the second surface of the substrate 1 to form the cavity Q, the following steps: S70. Etch the top surface of cavity Q at the corresponding position of release groove K1, so that the bottom of release groove K1 is connected to the etched area on the top surface of cavity, forming release opening K; thereby separating the free end B of cantilever beam 10 from substrate 1. (Reference) Figure 11 ) for Figure 1 The structure shown includes, after step S60, etching the substrate 1 from the second surface of the substrate 1 to form the cavity Q, the following steps: S61, A second opening O2 is formed by etching the substrate 1 from the top surface of the cavity Q to expose a portion of the bottom electrode 31. (Reference) Figure 12 ) S70. Etch the top surface of cavity Q at the corresponding position of release groove K1, so that the bottom of release groove K1 is connected to the etched area on the top surface of cavity, forming release opening K; thereby separating the free end B of cantilever beam 10 from substrate 1. (Reference) Figure 13 ) Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A micro-displacement detection device based on the frequency drift of a bulk acoustic resonator, characterized in that, include: A displacement transmission module and a displacement detection module; wherein, the displacement detection module includes: A cantilever beam, wherein one end of the cantilever beam is a fixed end and the other end is a free end; A bulk acoustic resonator is disposed between the fixed end and the free end of the cantilever beam; The displacement conversion structure is fixed to the free end of the cantilever beam; When the displacement transmission module moves, the displacement conversion structure can drive the cantilever beam to bend and deform under the push of the displacement transmission module, thereby changing the stress state of the bulk acoustic resonator and causing its resonant frequency to drift.

2. The micro-displacement detection device based on the frequency drift of a bulk acoustic resonator according to claim 1, characterized in that, Also includes: The frequency detection module is electrically connected to the bulk acoustic resonator; The frequency detection module is used to detect the resonant frequency drift of the bulk acoustic resonator and output the displacement according to the preset frequency drift-displacement mapping relationship.

3. The micro-displacement detection device based on the frequency drift of a bulk acoustic resonator according to claim 1, characterized in that, The displacement conversion structure has an inclined surface, and the displacement transmission module is in contact with the inclined surface of the displacement conversion structure. When the displacement transmission module moves, it slides along the inclined surface of the displacement conversion structure, driving the cantilever beam to bend and deform.

4. The micro-displacement detection device based on the frequency drift of a bulk acoustic resonator according to claim 3, characterized in that, The displacement transmission module includes a displacement rod and a displacement force application component, wherein the displacement force application component is disposed on the circumferential sidewall at one end of the displacement rod; When the displacement rod moves, the displacement force-applying component slides along the inclined surface of the displacement conversion structure, driving the cantilever beam to bend and deform.

5. The micro-displacement detection device based on the frequency drift of a bulk acoustic resonator according to claim 4, characterized in that, The inclined surface of the displacement conversion structure is a plane; The end of the displacement force-applying component that contacts the displacement conversion structure is a spherical surface.

6. The micro-displacement detection device based on the frequency drift of a bulk acoustic resonator according to claim 4, characterized in that, The displacement transmission module and the bulk acoustic resonator are located on the same surface of the cantilever beam.

7. The micro-displacement detection device based on the frequency drift of a bulk acoustic resonator according to claim 1, characterized in that, The bulk acoustic resonator includes a substrate, a bottom electrode, a piezoelectric layer, and a top electrode stacked in sequence. The bulk acoustic resonance also includes a first external electrode electrically connected to the bottom electrode and a second external electrode electrically connected to the top electrode.

8. The micro-displacement detection device based on the frequency drift of a bulk acoustic resonator according to claim 7, characterized in that, The cantilever beam is reused as the base.

9. The micro-displacement detection device based on the frequency drift of a bulk acoustic resonator according to any one of claims 1 to 8, characterized in that, The bulk acoustic resonator is a thin-film bulk acoustic resonator.

10. The micro-displacement detection device based on the frequency drift of a bulk acoustic resonator according to any one of claims 1 to 8, characterized in that, The bulk acoustic resonator is a high-order harmonic bulk acoustic resonator.

Images