An intra-resonance frequency comb based squeeze film air pressure sensor and method

Abstract

The application belongs to the technical field of MEMS resonant sensor, and particularly relates to a squeeze film gas pressure sensor and method based on internal resonance frequency comb; the sensor comprises a silicon substrate, a silicon dioxide layer is arranged on the silicon substrate, a resonant cavity, a gas channel, a square cavity, a source electrode and a drain electrode are arranged on the silicon dioxide layer, and a gate electrode is arranged on the silicon substrate corresponding to the resonant cavity, the gas channel and the square cavity; a two-dimensional diaphragm is arranged on the silicon dioxide layer, and the back end of the source electrode and the drain electrode and the resonant cavity are covered; the application realizes sensitivity amplification for gas pressure measurement based on the audio frequency comb effect, the audio frequency comb gas pressure sensing mechanism discloses the physical regulation mechanism of the internal resonance audio frequency comb in the two-dimensional resonator and the gas pressure sensing and sensitivity amplification mechanism, and provides a new solution for the difficult problem of the development of the muW level power consumption high-sensitivity gas pressure sensor.

Description

Technical Field

[0001] This invention belongs to the field of MEMS resonant sensor technology, and specifically relates to an extruded film pressure sensor and method based on an internal resonant frequency comb. Background Technology

[0002] Barometric pressure sensors are widely used in meteorology, aerospace, industrial automation, automotive, and consumer electronics. However, to date, the vast majority of high-precision pressure sensors still rely on imports and are expensive. Furthermore, traditional barometric pressure sensors are limited in performance by sensitivity, resolution, and stability, which restricts their widespread deployment in some high-end applications. In recent years, with the rapid development of MEMS technology, barometric pressure sensors have also seen extensive development. Among them, resonant sensors characterize pressure by detecting the resonant frequency of a resonator, and their high precision, high sensitivity, and fast response give them a performance advantage in certain specific fields.

[0003] While resonant MEMS pressure sensors offer superior performance, their fabrication process is highly complex, resulting in high manufacturing costs and low yields. Extruded diaphragm pressure sensors are a type of resonant pressure sensor, consisting of a cavity and a diaphragm. Changes in external air pressure cause a shift in the resonant frequency, with the magnitude of this frequency shift characterizing the change in external air pressure. A key feature of this structure is that it does not require an enclosed internal cavity; the internal cavity is open to the external air pressure. This structure not only simplifies manufacturing but also allows for the generation of a frequency comb phenomenon. A frequency comb is a set of frequency components with uniform spacing and a coherent, stable phase relationship generated in the frequency spectrum. Its unique equidistant characteristic of adjacent comb teeth allows us to amplify the fundamental frequency shift by a multiple of the number of comb teeth, significantly improving measurement sensitivity. Based on this principle, if the sensitivity of extruded diaphragm sensors can be amplified using the internal resonant frequency comb phenomenon, it holds promise for a technological breakthrough, filling the gap in high-end pressure sensor products and providing technical support for aerospace, consumer electronics, industrial control, and future emerging applications. Summary of the Invention

[0004] To overcome the above problems, this invention provides a squeeze-film pressure sensor and method based on an internal resonant frequency comb; it develops an NEMS high-sensitivity squeeze-film pressure sensor based on the acoustic comb effect to achieve sensitivity amplification using two-dimensional nanomaterials, and its manufacturing process reveals the physical modulation mechanism of the internal resonant acoustic comb in the two-dimensional resonator and the pressure sensing and sensitivity amplification mechanism. Furthermore, the optimized manufacturing process can significantly simplify the processing flow, providing a novel solution to the challenge of developing high-sensitivity pressure sensors with μW-level power consumption.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A pressure sensor for extruded diaphragm pressure based on an internal resonant frequency comb for sensitivity amplification includes: A silicon substrate 4 has a silicon dioxide layer 3 thereon. The silicon dioxide layer 3 has a resonant cavity 2, a gas channel 5, a square cavity, a source electrode 11, and a drain electrode 12. The resonant cavity 2 and the square cavity are connected through the gas channel 5. A gate electrode 13 is laid on the silicon substrate 4 corresponding to the resonant cavity 2, the gas channel 5, and the square cavity. A two-dimensional diaphragm 6 is laid on a silicon dioxide layer 3, covering the rear ends of the source electrode 11 and the drain electrode 12 as well as the resonant cavity 2.

[0006] The resonant cavity 2 has a source electrode 11 and a drain electrode 12 on both sides of its front end, and a two-dimensional diaphragm 6 is laid on the silicon dioxide layer 3, which can partially cover the resonant cavity 2 and the corresponding source electrode 11 and drain electrode 12 on both sides of the resonant cavity 2.

[0007] The source electrode 11 and drain electrode 12 have the same structure, each including a square sheet located at the front end of the surface of the silicon dioxide layer 3 and a long strip located in the middle of the surface of the silicon dioxide layer 3. The end of the square sheet extends towards the rear end of the silicon dioxide layer 3 to form a long strip.

[0008] The two-dimensional diaphragm 6 is laid on the silicon dioxide layer 3 and can cover the resonant cavity 2, the long strip of the source electrode 11, and the long strip of the drain electrode 12.

[0009] A method for measuring air pressure using a squeeze-film pressure sensor with sensitivity amplification based on an internal resonant frequency comb includes the following: Step 1, DC bias adjustment: Step 1.1: Place the pressure sensor inside the vacuum test chamber and simultaneously irradiate the two-dimensional thin film 6 with the detection light source and the excitation light source; Step 1.2, apply a DC bias voltage V to the gate electrode 13. dc It gradually increases from 0V; Step 1.3: The light intensity of the interference fringes generated when the two-dimensional thin film 6 vibrates is collected by a photodetector as a function of time. The light intensity signal is converted into an electrical signal by the photodetector and sent to a lock-in amplifier for spectrum analysis to obtain the amplitude-frequency response curve. Step 1.4, during the DC bias adjustment process, until the harmonic relationship between the first-order resonant frequency ω1 and the second-order resonant frequency ω2 of the two-dimensional thin film 6 in the obtained amplitude-frequency response curve is as follows: At that time, the DC bias voltage adjustment is completed; Step 2: Calibrate the sensitivity of the barometric pressure sensor: Step 2.1: Apply an increasing AC voltage to the gate electrode 13 until the obtained amplitude-frequency response curve changes from a single-peak shape to a symmetrical double-peak shape; the AC voltage at this time is recorded as the target AC voltage, and at this time, the first-order mode amplitude-frequency curve and the second-order mode amplitude-frequency curve have an intersection region, and the frequency range corresponding to this region is the bifurcation quasi-static region. Step 2.2, Confirmation of the fixed-frequency excitation frequency Ω: Step 2.21: Control the reference frequency of the lock-in amplifier to the quasi-static region. Perform a frequency sweep analysis within this range to obtain the amplitude-frequency response curve. The frequency value corresponding to the lowest point of the dip in the middle of the first-order mode amplitude-frequency curve is f. d The frequency value corresponding to the highest point of the bulge in the middle of the second-order mode amplitude-frequency curve is f. p Record f d to f p All frequency points, including the endpoints; Step 2.22: Retain frequency points with amplitude fluctuations less than 5% from all frequency points as candidate frequency points, where the amplitude fluctuation of a frequency point = (amplitude of that frequency point - average amplitude of all frequency points) ÷ average amplitude of all frequency points * 100%; Step 2.23: Apply AC voltages at each candidate frequency point to the gate electrode 13 respectively, and collect the current signal output by the drain electrode 12 each time a different frequency AC voltage is applied, and send the current signal to the lock-in amplifier. The lock-in amplifier will perform spectrum analysis on the current signal to obtain the acoustic frequency comb image. Step 2.24: Select the acoustic frequency comb image that meets the following conditions from each acoustic frequency comb image as the candidate acoustic frequency comb image: A. The spacing deviation between any two adjacent comb teeth is <1%, where the spacing deviation between two adjacent comb teeth = (the spacing between two adjacent comb teeth - the average spacing of all comb teeth) ÷ the average spacing of all comb teeth * 100%; B. The difference between the amplitude corresponding to the frequency of the main comb tooth and the amplitude corresponding to the frequency of the comb teeth on both sides is >10dB; C. Each time an AC voltage of a certain frequency is applied to the gate electrode 13, the process must be repeated multiple times, and the resulting acoustic frequency comb image is the same each time. Step 2.25: Among the obtained candidate acoustic frequency comb images, select the candidate acoustic frequency comb image with the most comb teeth and the largest amplitude corresponding to the main comb teeth as the target acoustic frequency comb image, and the frequency of the AC voltage applied to it is the fixed frequency excitation frequency Ω. Step 2.3: Conduct a pressure calibration experiment and establish a pressure-frequency comb response model. Under different known air pressures, a constant frequency AC voltage V of Ω is applied to the gate electrode 13. ac, thus obtaining the acoustic frequency comb image; Step 2.4, calculate the frequency shift δf of the end comb teeth in the acoustic frequency comb image using the following formula. end : δf end =f end (p)-f end (p0); Where: f end (p) represents the frequency value of the end teeth of the acoustic frequency comb under the current known air pressure p, and f end (p0) is the initial frequency value of the end comb teeth in the acoustic frequency comb under the known air pressure p is the initial air pressure p0=10Pa; Step 2.5, input the known pressure p and the corresponding δf end The data is fitted to obtain the sensing line, and the slope S of the sensing line is determined, which is the sensitivity of the barometric pressure sensor. Step 3, Air Pressure Calculation Step 3.1: Place the barometric pressure sensor in an environment with unknown pressure and apply a constant frequency AC voltage V of Ω to the gate electrode 13. ac Drive the air pressure sensor to obtain an acoustic frequency comb image; Step 3.2: Calculate the frequency shift δf of the end comb teeth in the acoustic frequency comb image under this air pressure, following the steps in Step 2.4. end ; Step 3.3, calculate the air pressure p of the environment where the barometer sensor is located using the following formula. amb : p amb =S*δf end .

[0010] Steps one through three are all performed inside a vacuum test chamber.

[0011] A method for fabricating a squeeze-film pressure sensor with sensitivity amplification based on an internal resonant frequency comb includes the following: Step 1: Take a purchased 4-inch silicon wafer as the silicon substrate 4, and grow a 300nm thick silicon dioxide layer 3 on it through a thermal oxidation process. Then, pattern the silicon dioxide layer 3 through a photolithography process to etch out the resonant cavity 2, gas channel 5, and square cavity. The window where the resonant cavity 2, gas channel 5, and square cavity are located provides space for the gate electrode 13 to be deposited on the silicon substrate 4. The gate electrode 13 is sputtered into the cavity where the resonant cavity 2, gas channel 5, and square cavity are located, and is in contact with the silicon substrate 4, but does not fill the resonant cavity 2, gas channel 5, and square cavity. Step 2: Spin-coat photoresist onto the silicon dioxide layer 3 after photolithography, and use a mask to pattern the source electrode 11, drain electrode 12, and gate electrode 13 (cover the photoresist with a mask, expose, develop, and etch), while retaining the resonant cavity 2, gas channel 5, and square cavity for sputtering electrodes. Step 3: A 100nm thick chromium (Cr) metal layer and a gold (Au) metal layer are sequentially sputtered on the patterned silicon dioxide layer 3. The photoresist is then removed to obtain the source electrode 11, drain electrode 12, and gate electrode 13. Step four: The two-dimensional diaphragm 6 is transferred onto the resonant cavity 2, the source electrode 11, the drain electrode 12 and the silicon dioxide layer 3. The resonant cavity 2 between the two-dimensional diaphragm 6 and the silicon dioxide layer 3 forms a suspended drum-shaped structure, thus completing the processing of the barometric pressure sensor.

[0012] The beneficial effects of this invention are: This invention proposes an active control method for the acoustic comb configuration by establishing a high-precision internal resonance acoustic comb theoretical model of a two-dimensional graphene resonant band. This provides theoretical guidance for accurately exciting the required acoustic comb configuration. This helps solve common problems in the field and achieve precise control and optimization of the acoustic comb configuration.

[0013] This invention clarifies the evolution law of the acoustic comb during external air pressure changes and elucidates the ultra-low power extrusion membrane air pressure sensing mechanism based on an internal resonant acoustic comb. This provides a principle scheme for achieving μW-level sensing power consumption and micro-pressure detection, thereby greatly improving the sensitivity and detection limit of air pressure sensors.

[0014] This invention reveals the key scientific issues of the evolution law of the internal resonant audio comb and the frequency response amplification mechanism when the external air pressure changes. It provides a method for accurately measuring the audio comb signal of a two-dimensional NEMS resonator by electricity, and reveals the ultra-low power trace air pressure sensing mechanism based on the audio comb, which further improves the performance and application value of the sensor. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention 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 the content of the embodiments of the present invention and these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of the air pressure sensor of the present invention; Figure 2 This is a top view of the barometric pressure sensor of the present invention; Figure 3It utilizes modal coupling to generate the thin-film vibration mode diagrams required for frequency comb generation; Figure 4 This is a schematic diagram showing the regulation of the first and second order mode resonant frequencies and their frequency ratios by DC voltage adjustment. Figure 5 This is a schematic diagram of the air pressure sensing principle and sensitivity amplification based on the frequency comb extrusion film principle; In the figure: 1. Electrode, 11. Source electrode, 12. Drain electrode, 13. Gate electrode; 2. Resonant cavity; 3. Silicon dioxide layer; 4. Silicon substrate; 5. Gas channel; 6. Two-dimensional diaphragm. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0018] Example 1 This invention utilizes MEMS fabrication technology to manufacture a grooved diaphragm structure capable of generating a frequency comb. The resonant cavity 2 can be circular, square, or elongated.

[0019] The material of the two-dimensional diaphragm 6 is graphene or molybdenum disulfide.

[0020] Based on thin film theory and the principle of internal resonance, this invention establishes a high-precision nonlinear motion model of the two-dimensional NEMS resonant band under significant size effects using the energy method. It reveals the structure-effect relationship between the configuration of the audio comb and its internal and external parameters, proposes an active control method for the configuration of the internal resonant audio comb, and uses the principle of extruded membrane to link air pressure with vibration offset, thus applying the internal vibration frequency comb to the field of sensing.

[0021] This invention utilizes the equal spacing and disturbance sensitivity of an acoustic comb to transform changes in external physical quantities into changes in comb tooth spacing under low-power, fixed-frequency driving conditions. Furthermore, it leverages the frequency locking and harmonic effects of multi-order comb teeth to exponentially enhance sensitivity, thereby constructing an ultra-low-power, ultra-high-performance trace gas sensing mechanism. This invention precisely constructs an acoustic comb with a large amplitude and multiple comb teeth to improve sensing resolution and sensitivity.

[0022] Please see Figure 1 and Figure 2 The embodiments of the present invention include: First, a high-sensitivity NEMS squeeze-film pressure sensor based on the acoustic comb effect and developed using two-dimensional nanomaterials was designed. This sensor comprises a two-dimensional diaphragm 6 and a resonant cavity 2 formed by the diaphragm, silicon substrate 4, and silicon dioxide layer 3. The resonant cavity 2 is connected to the external air through a channel 5, ultimately forming a drum-shaped resonator-type squeeze-film pressure sensor with its inner cavity connected to the atmosphere. The two-dimensional diaphragm 6 is constructed using single-layer graphene, molybdenum disulfide, and other two-dimensional NEMS materials, possessing excellent mechanical, electrical, and gas-sensitive properties. The resonant cavity 2 is not limited to a drum shape; strip-shaped, square, etc., can also be used as the pressure sensor structure of this invention. Specifically: A pressure sensor for extruded diaphragm pressure based on an internal resonant frequency comb for sensitivity amplification includes: A silicon substrate 4 has a silicon dioxide layer 3 on it. The silicon dioxide layer 3 has a resonant cavity 2, a gas channel 5, a square cavity, a source electrode 11, and a drain electrode 12. The resonant cavity 2 and the square cavity are connected through the gas channel 5. A gate electrode 13 is laid on the silicon substrate 4 corresponding to the resonant cavity 2, the gas channel 5, and the square cavity (the gate electrode 13 is set according to the shape of the resonant cavity 2, the gas channel 5, and the square cavity). A two-dimensional diaphragm 6 is laid on a silicon dioxide layer 3, covering the rear ends of the source electrode 11 and the drain electrode 12 as well as the resonant cavity 2.

[0023] The resonant cavity 2 has a source electrode 11 and a drain electrode 12 on both sides of its front end, and a two-dimensional diaphragm 6 is laid on the silicon dioxide layer 3, which can partially cover the resonant cavity 2 and the corresponding source electrode 11 and drain electrode 12 on both sides of the resonant cavity 2.

[0024] The source electrode 11 and the drain electrode 12 have the same structure, each including a square sheet located at the front end of the surface of the silicon dioxide layer 3 and a long strip located at the rear end of the surface of the silicon dioxide layer 3. The end of the square sheet extends towards the rear end of the silicon dioxide layer 3 to form a long strip.

[0025] The two-dimensional diaphragm 6 is laid on the silicon dioxide layer 3 and can cover the resonant cavity 2 and the source electrode 11 strip and drain electrode 12 strip on both sides of the resonant cavity 2. It should be emphasized here that the two-dimensional diaphragm 6 needs to completely cover the two-dimensional diaphragm 2, but the covered portion of the source electrode 11 strip and drain electrode 12 strip is not the entire strip, but only the strip corresponding to the strip on both sides of the resonant cavity 2.

[0026] A pressure sensor based on an internal resonant frequency comb for amplified sensitivity includes a circular window formed by etching a silicon dioxide layer 3 using a buffered hydrofluoric acid (BHF) solution, which serves as a resonant cavity 2; a silicon substrate 4; a silicon dioxide layer 3 on the silicon substrate 4 formed by thermal oxidation; a cuboid gas channel 5 etched within the silicon dioxide layer 3; a cubic cavity at the end of the channel; a two-dimensional diaphragm 6 bonded to the surface of the silicon dioxide layer 3 by van der Waals forces; a source electrode 11 and a drain electrode 12 sputtered and deposited on both sides of the silicon dioxide layer 3; a gate electrode 13 sputtered into the cubic cavity connected to the end of the gas channel 5; and a gate electrode 13 on the silicon substrate 4, wherein the silicon dioxide layer 3 is fixed to the silicon substrate 4 by thermal oxidation.

[0027] Secondly, this invention reveals the theoretical basis for driving the barometric pressure sensor to generate a frequency comb effect. To achieve modal coupling and thus generate a frequency comb effect, it is necessary to adjust the modal frequencies to modify the coupling form of mode one and mode two. Specifically, this is achieved by adjusting the DC bias voltage V between the source electrode 11 and the gate electrode 13. dc To achieve modulation of the modal frequency coupling, we revealed the DC voltage regulation law through theoretical derivation and numerical simulation, enabling the pressure sensor to deterministically generate a frequency comb phenomenon. More specifically, adjusting the DC bias voltage V between the gate and drain... dc If the frequency ratio ω2 / ω1 is around 1:2, the amplitude-frequency curve will change from a single-peak form to a more symmetrical double-peak form. At the concave part of the first-mode amplitude-frequency curve, the second-mode amplitude-frequency curve will produce a small bulge. This small nonlinear region, namely the bifurcation quasi-static region, is where internal vibration occurs. In the bifurcation quasi-static region, the pressure sensor is driven at a fixed frequency, and the drain output current signal of the pressure sensor will generate a frequency comb in the frequency domain.

[0028] Finally, the frequency comb phenomenon was combined with the principle of extruded membrane air pressure sensing for the first time, and an air pressure sensing sensitivity amplification mechanism based on the acoustic comb effect was proposed. When the external air pressure of the NEMS high-sensitivity extruded membrane air pressure sensor changes, the change in external air pressure will affect the surface tension of the two-dimensional thin film 6 during vibration, causing a frequency shift in the natural frequency (center frequency) of the air pressure sensor, which in turn causes a frequency shift in the spacing of the frequency comb. The frequency shift of the end comb teeth will be amplified by a factor of 1. The change in air pressure is characterized by the frequency shift of the end comb teeth, thus realizing the air pressure sensing sensitivity amplification based on the acoustic comb effect.

[0029] To generate the frequency comb effect and realize a high-sensitivity NEMS extruded diaphragm pressure sensor based on the acoustic frequency comb effect sensitivity amplification, it is necessary to adjust the DC bias voltage V. dc Adjust the coupling frequency ratio between mode 1 and mode 2. The vibration modes of mode 1 and mode 2 are shown in [reference needed]. Figure 3 Due to the AC drive voltage V in the total drive voltage V acThe alternating current causes a change in the electrostatic force between the two-dimensional diaphragm 6 and part of the gate electrode 13, resulting in vibration. The vibration modes of the two-dimensional diaphragm 6 are as follows: Figure 3 As shown, the DC bias voltage V between the source electrode 11 and the gate electrode 13 connected to the external power supply can be gradually adjusted. dc This is to achieve mode frequency coupling adjustment. This is done by continuously changing the AC drive voltage V in the simulation. ac DC bias voltage V when =0 dc By observing the resonant frequency ω2 of mode two, the resonant frequency ω1 of mode one, and the frequency ratio ω2 / ω1 between the two modes, the DC voltage regulation law was revealed through simulation. (See [link to simulation]). Figure 4 DC bias voltage V dc The adjustment curve of the frequency ratio ω2 / ω1 between the resonant frequency ω2 of mode two and the resonant frequency ω1 of mode one exhibits an M-shape, and the DC bias voltage V dc The adjustment curve of the resonant frequency f1 of mode one exhibits a W-shape, and the DC bias voltage V dc The adjustment curve of the initial bias displacement W0 of the two-dimensional diaphragm 6 exhibits a U-shape. The DC bias voltage V applied to the gate electrode 13 is adjusted. dc By aligning the frequency ratio ω2 / ω1 of the first-order mode to that of the second-order mode to approximately 2:1, the amplitude-frequency curve will change from a single-peak to a double-peak pattern. (See [reference needed]). Figure 4 At the concave point of the amplitude-frequency curve of mode 1, a small bulge will appear in the amplitude-frequency curve of mode 2. A nonlinear region exists within this small area. (See [reference needed]). Figure 5 The circular marked area in (b) corresponds to a frequency range called the bifurcation quasi-static region, where an internal vibration frequency comb phenomenon occurs in the vibration frequency domain. Within the frequency range where the acoustic frequency comb is generated (quasi-static region), the signal generator applies a fixed-frequency AC voltage V of Ω to the gate electrode 13. ac The two-dimensional diaphragm 6 is driven to convert the output current signal I of the drain electrode 12 of the air pressure sensor into a spectrum signal through Fourier transform (FFT). This spectrum signal will generate a frequency comb in the frequency domain, amplifying the frequency shift caused by air pressure changes, which serves as the basis for amplifying the sensor's sensitivity.

[0030] The driving frequency Ω is Figure 5 (b) The specific range of the frequency range corresponding to the circular marked area varies from sensor to sensor. It is necessary to sweep the frequency to obtain the amplitude-frequency curve, and then gradually change the driving frequency to drive at a fixed frequency. The driving frequency when the frequency comb is generated is the start of this region, and the region where the frequency comb teeth are generated is the end of this region.

[0031] A pressure sensor based on the acoustic comb effect and a squeezed diaphragm NEMS pressure sensor is disclosed. The sensitivity amplification mechanism under the frequency shift and doubling effect of the acoustic comb is established. This includes: addressing the application of the acoustic comb effect in sensing and the construction of the sensitivity amplification mechanism; utilizing the equidistant characteristics of the acoustic comb teeth, the NEMS high-sensitivity squeezed diaphragm pressure sensor, based on the acoustic comb effect sensitivity amplification, addresses the issue that changes in external air pressure affect the surface tension of the two-dimensional diaphragm 6 during vibration, causing a frequency shift in the sensor's natural frequency (the center frequency of the frequency comb). The frequency shift δf of the center frequency of the frequency comb teeth conforms to the pressure sensing principle of squeezed diaphragms (squeezed diaphragms generally refer to resonant drum models that utilize the squeezed diaphragm principle for pressure sensing). , where ω center δf represents the initial center comb frequency, p represents the frequency shift of the center frequency of the comb teeth, and p represents the frequency shift of the center frequency of the comb teeth. amb Representing external air pressure, the frequency shift δf is derived from the initial center comb frequency ω. center and external air pressure p amb The frequency shift δf changes, and the frequency comb spacing d (see...) Figure 5 (e) ), with frequency shift δf of the center frequency and AC drive voltage V ac The frequency Ω changes with the frequency, and the variation law of the frequency comb tooth spacing δd is as follows: δd can be obtained by feature extraction and simple calculation of the frequency image after Fourier transform of the output current signal detected by drain electrode 12; however, due to the equal spacing characteristic of the comb teeth, changes in air pressure will cause equal spacing changes δd in the frequency of the comb teeth. If the number of comb teeth is N, then the frequency shift of the end comb teeth is δd. end Represented as N*δd, the frequency shift caused by air pressure changes will be amplified by a factor of N, and the frequency ω of the end comb teeth will be extracted. end For sensing, see Figure 5 (e) Due to the equidistant amplification effect of the frequency comb teeth, the frequency shift δd of the end comb teeth is used. end The sensitivity of the sensor will also be N times the number of comb teeth required for the frequency shift δd of all traditional sensors; based on this principle, the extruded membrane pressure sensor of this invention, which amplifies sensitivity using an internal resonant frequency comb, can achieve highly sensitive detection of pressure changes. The structural design is adjusted to increase the frequency shift δd of the device. end The pressure sensor exhibits a good linear relationship with changes in air pressure within its sensing range. Subsequently, a pressure calibration experiment was conducted. Specifically, the pressure sensor was placed within a pressure-adjustable chamber, and a precision barometer was used to measure the air pressure p within the chamber. amb Simultaneously, the frequency shift δd of the last comb tooth output by the extruded film pressure sensor, which is driven by the internal resonant frequency comb sensitivity amplification, is detected. endMultiple sets of data were measured, a sensing straight line was fitted, and the slope of the fitted sensing straight line was determined to be the sensitivity S of the extruded membrane pressure sensor based on the sensitivity amplification of the internal resonant frequency comb. The output pressure p was sensed using the end comb teeth. amb =S*δd end .

[0032] A fabrication process for an extruded NEMS pressure sensor based on the acoustic comb effect includes: solving the manufacturing problem of the designed pressure sensor; fabricating the sensor base using processes such as photolithography, etching, and metal sputtering; and transferring the prepared monolayer graphene onto the sensor base in a two-step process. The specific fabrication scheme is as follows: Step 1: Using plasma-enhanced chemical vapor deposition (PECVD) process, a silicon substrate 4 made of TEOS (tetraethoxysilane) material is used; silicon substrate 4 and oxygen are introduced into the PECVD reaction chamber, and the high energy of the plasma is used to promote the reaction, forming a 250nm thick silicon dioxide film on the silicon substrate 4, namely silicon dioxide layer 3. This silicon dioxide layer can be used as an insulating layer or a sacrificial layer. Step 2: Using OFPR 800LB34CP photoresist, spin coater is rotated at 500 rpm for 5 seconds to initially spread the photoresist on the surface of silicon dioxide layer 3. Then, the spin coater is accelerated to 3000 rpm and held for 30 seconds to evenly coat the photoresist on the surface of silicon dioxide layer 3, forming a photoresist layer of the required thickness. Generally, the faster the spin coating speed, the thinner the photoresist layer. The spin-coated wafer is placed on a hot plate and heated at 110℃ for 5 minutes for soft baking. This process causes the solvent in the photoresist to evaporate, allowing the photoresist layer to dry, harden, and firmly adhere to silicon dioxide layer 3. After drying the photoresist, the wafer is exposed using a photolithography machine. Step 3: Immerse the exposed wafer in a 2.38% (w / w) TMAH (tetramethylammonium hydroxide) solution for 60 seconds. TMAH is a commonly used developer, particularly suitable for positive photoresist. The developer dissolves the exposed areas, revealing the pattern. The development time should be precisely controlled to ensure pattern accuracy and resolution. Development forms the photolithographic patterns of resonant cavity 2, cuboid gas channels 5, and square cavities; thus removing the photoresist in the areas containing resonant cavity 2, cuboid gas channels 5, and square cavities. After development, the wafer is immediately transferred to deionized water and rinsed for 30 seconds to remove residual developer from the surface, preventing over-development or pattern defects. Then, a second rinse with deionized water is performed for 30 seconds to ensure that the developer residue is completely removed, further improving the clarity and edge resolution of the pattern.

[0033] Step 4: Use buffered hydrofluoric acid (BHF) solution (HF:NH4F=9:100). BHF solution is suitable for etching silicon dioxide layer 3, has good selectivity, and has little impact on silicon layer and photoresist. Etch on the wafer for 120 seconds at a rate of 200nm / min, with an etching depth of about 400nm, to form resonant cavity 2, cuboid gas channel 5 and square cavity. Step 5: Immerse the sample in acetone for 5 minutes to remove any remaining photoresist. Acetone is an organic solvent that effectively dissolves photoresist. Then, treat with O2 plasma for 30 minutes to remove any remaining organic matter and fine photoresist particles. This step thoroughly cleans the sample surface, improving adhesion for subsequent steps.

[0034] Step Six: First, coat the upper surface of the wafer with a LOR-5A photoresist remover layer, then coat with OFPR 800LB 34CP photoresist; this forms a double-layer photoresist structure, making the subsequent stripping process easier. Spin coat the photoresist at 500 rpm for 5 seconds to initially spread the photoresist, then accelerate to 3000 rpm for 30 seconds to evenly coat the photoresist layer; place the sample on a hot plate at 110℃ and bake for 5 minutes to remove the solvent and harden the photoresist. After drying the hardened photoresist, expose the wafer using a photolithography machine. Step 7: Immerse the exposed sample in a 2.38% (w / w) TMAH solution for 90 seconds for development. The development time is relatively long to ensure thorough development. Development forms the photolithographic pattern of source electrode 11, drain electrode 12, and gate electrode 13, removing the photoresist in the areas containing source electrode 11, drain electrode 12, and gate electrode 13. Rinse twice with deionized water. The first rinse is for 30 seconds in deionized water to remove the developer; the second rinse is also for 30 seconds in deionized water to ensure a clean surface. Step 8: Using an electron beam evaporation apparatus, deposit 10 nm thick chromium (Cr) and 10 nm thick gold (Au) films on the silicon dioxide layer 3 at the positions corresponding to the source electrode 11, drain electrode 12, and gate electrode 13. The chromium layer is used to enhance the adhesion between the gold and the substrate. The evaporation rate is set to 0.4 Å / s to ensure the uniformity and adhesion of the films, forming the source electrode 11, drain electrode 12, and gate electrode 13. Step 9: Place the sample in acetone for 15 minutes of ultrasonic cleaning to remove excess metal and photoresist, expose the patterned metal structure, and use TMAH solution to remove the LOR-5A photoresist removal layer to ensure a clean surface and reveal the final patterned structure. Step 10: First, a uniform monolayer of graphene is generated on copper foil using chemical vapor deposition (CVD). The grown graphene surface is cleaned with deionized water to ensure the absence of organic or inorganic contamination, thus guaranteeing the transfer effect. A layer of PMMA is coated on the graphene surface to provide mechanical support and prevent the graphene from cracking during the transfer process. The PMMA-coated graphene-copper composite layer is then immersed in a copper etchant (such as a 0.1 M ammonium persulfate solution) to etch away the copper layer and release the graphene film. The PMMA / graphene film is then transferred to deionized water for rinsing, and this rinsing is repeated several times to completely remove any residual etchant. The PMMA / graphene film is then removed from the water and gently applied to the target MEMS device, i.e., the sample processed in Step 9, at the desired location. Good contact between the PMMA / graphene film and the device surface is ensured. The film is then gently baked at 80℃-100℃ for a few minutes to ensure strong adhesion between the graphene film and the device surface and to remove any residual moisture, forming a two-dimensional diaphragm 6.

[0035] Example 2 Similar to Example 1, the difference lies in a method for measuring air pressure using a squeeze-film pressure sensor with sensitivity amplification based on an internal resonant frequency comb, comprising the following: Step 1, DC bias adjustment: Step 1.1: Place the pressure sensor inside the vacuum test chamber, select a red laser with a wavelength of 633nm as the detection light source, and select a blue laser with a wavelength of 405nm as the excitation light source. Simultaneously irradiate the two-dimensional thin film 6 with the detection light source and the excitation light source. Step 1.2, apply a DC bias voltage V to the gate electrode 13. dc Starting from 0V and gradually increasing, when the two-dimensional thin film 6 vibrates, the phase difference between the reflected and transmitted light of the red laser will change, and they will meet in space and interfere, forming interference fringes. Step 1.3: The light intensity of the interference fringes generated when the two-dimensional thin film 6 vibrates is collected by a photodetector as a function of time. The light intensity signal is converted into an electrical signal by the photodetector and sent to a lock-in amplifier for spectrum analysis. The electrical signal is then subjected to Fourier analysis by the lock-in amplifier to obtain the amplitude-frequency response curve. Specifically: The lock-in amplifier performs frequency sweep analysis by adjusting the reference frequency to extract the amplitude of the electrical signal at each frequency point, thereby obtaining the amplitude-frequency response curve of the two-dimensional thin film 6, where the reference frequency is the excitation frequency of the excitation light, such as... Figure 5As shown in (a), the amplitude-frequency response curve has the excitation signal frequency of the excitation light source loaded on the two-dimensional thin film 6 as the horizontal axis (unit: Hz); and the response amplitude (i.e. voltage amplitude, unit: V) obtained after Fourier analysis by the lock-in amplifier as the vertical axis. The voltage amplitude is proportional to the vibration amplitude of the two-dimensional thin film 6 at the corresponding excitation frequency. The curve reflects the vibration response characteristics of the two-dimensional thin film 6, and the peak frequency in the curve corresponds to the resonance frequency of the two-dimensional thin film 6. The figure includes two amplitude-frequency response curves: one of which represents the first mode of the two-dimensional thin film 6. The amplitude-frequency response curve corresponds to the first-order vibration mode of the two-dimensional thin film 6, with its peak position representing the first-order resonant frequency ω1; the other amplitude-frequency response curve is the amplitude-frequency response curve of the second-order mode of the two-dimensional thin film 6, corresponding to the second-order vibration mode of the two-dimensional thin film 6, with its peak position representing the second-order resonant frequency ω2; as shown Figure 3 As shown; Step 1.4: During the DC bias adjustment process in steps 1.1-1.3, the corresponding amplitude-frequency response curve is obtained under each DC bias, until the harmonic relationship between the first-order resonant frequency ω1 and the second-order resonant frequency ω2 of the two-dimensional thin film 6 in the obtained amplitude-frequency response curve is... At that time, the DC bias voltage adjustment is completed; Step 2: Calibrate the sensitivity of the barometric pressure sensor: Step 2.1: Apply a gradually increasing AC voltage to the gate electrode 13 until the amplitude-frequency response curve obtained through the lock-in amplifier changes from a single-peak shape to a more symmetrical double-peak shape. This AC voltage is denoted as the target AC voltage. At this point, the first-mode amplitude-frequency curve and the second-mode amplitude-frequency curve intersect. This region corresponds to the depression in the first-mode amplitude-frequency curve (i.e., the valley between the two resonance peaks) and the convexity in the second-mode amplitude-frequency curve. The frequency range corresponding to the convexity is the nonlinear characteristic region, i.e., the quasi-static region of the bifurcation; that is, the critical transition interval before and after the system undergoes Hopf bifurcation (or saddle junction bifurcation) in the nonlinear dynamic response. Its specific characteristics and definition are as follows: This region precisely corresponds in the frequency domain to the entire frequency range where the right slope of the first-mode main resonance peak begins to decline, shows a depression, and eventually recovers and rises again. Furthermore, this frequency range completely coincides with the frequency range where the second-mode response shows a localized small convexity. Within this frequency range, although the system experiences amplitude modulation (such as first-order dips and second-order bulges), it has not yet entered a completely chaotic or unstable state. The rate of evolution of the vibration state slows down, and the change in amplitude over time exhibits a slow, approximately linear transition characteristic, meaning the system is in a "quasi-static" steady-state evolution process.

[0036] Step 2.2, confirming the fixed-frequency excitation frequency Ω, refers to selecting a specific excitation frequency value from the effective frequency range capable of exciting the sound frequency comb—that is, the aforementioned bifurcation quasi-static region—through the following steps: Step 2.21, Frequency Sweep Positioning: Under the target DC bias, a photodetector is used to collect the signal of the light intensity changing over time as interference fringes are generated by the vibration of the two-dimensional thin film 6. This light intensity signal is converted into a corresponding electrical signal and sent to a lock-in amplifier. The reference frequency of the lock-in amplifier is controlled within the quasi-static region. Frequency sweep analysis is performed within this range to obtain the amplitude-frequency response curve. The frequency value corresponding to the lowest point of the depression in the middle of the first-order mode amplitude-frequency curve is f. d The frequency value corresponding to the highest point of the bulge in the middle of the second-order mode amplitude-frequency curve is f. p Record f d to f p All frequency points including the endpoints (including f) d与 f p (two endpoints) Step 2.22, Filtering range: Retain frequency points with amplitude fluctuation less than 5% among all frequency points as candidate frequency points, where the amplitude fluctuation corresponding to a certain frequency point = (amplitude corresponding to that frequency point - average amplitude of all frequency points) ÷ average amplitude of all frequency points * 100%; Step 2.23, frequency verification: Apply AC voltages at each candidate frequency point to the gate electrode 13, and excite for more than 30 seconds. The response amplitude fluctuation is less than 2%. When applying AC voltages of different frequencies, the current signal output by the drain electrode 12 is collected and sent to the lock-in amplifier. The lock-in amplifier performs spectral analysis on the current signal to obtain the acoustic frequency comb image. Step 2.24: Select the acoustic frequency comb image that meets the following conditions from each acoustic frequency comb image as the candidate acoustic frequency comb image: A. The deviation between any two adjacent comb teeth is <1%, where the deviation between two adjacent comb teeth = (the distance between two adjacent comb teeth - the average distance between all comb teeth) ÷ the average distance between all comb teeth * 100%; the average distance between all comb teeth refers to the average distance between all two adjacent comb teeth; the distance between two adjacent comb teeth is described here as the distance between two adjacent comb teeth. B. The difference between the amplitude corresponding to the frequency of the main comb tooth and the amplitude corresponding to the frequency of the comb teeth on both sides is >10dB, and the spectrum is pure with no stray components. C. Each time an AC voltage of a certain frequency is applied to the gate electrode 13, the process is repeated multiple times, and the resulting acoustic frequency comb image is the same each time, that is, the same acoustic frequency comb characteristics can be reproduced. Step 2.25: Among the obtained candidate acoustic frequency comb images, select the candidate acoustic frequency comb image with the most comb teeth and the largest amplitude corresponding to the main comb teeth as the target acoustic frequency comb image, and the frequency of the AC voltage applied to it is the fixed frequency excitation frequency Ω. Step 2.3: Conduct a pressure calibration experiment and establish a pressure-frequency comb response model. The pressure sensor is placed in the pressure-adjustable cavity, and an AC voltage V with a fixed frequency of Ω is applied to the gate electrode 13 under different known pressures. ac The sensor is activated to obtain an acoustic frequency comb image. The acoustic frequency comb image contains a central comb tooth with the largest amplitude (corresponding to the main resonance response of the system) and several sidelobe comb teeth symmetrically distributed on both sides. When the external air pressure of the air pressure sensor changes, the surface tension of the two-dimensional thin film 6 changes accordingly, causing the natural frequency (i.e., the linear resonant frequency) of the air pressure sensor to shift. This shift will cause a collective frequency shift of the entire acoustic frequency comb. According to the nonlinear coupling characteristics, the frequency shift of the end comb teeth far from the center frequency is amplified by multiples. Therefore, by detecting the frequency shift of the end comb teeth relative to the reference state, high-sensitivity air pressure detection can be achieved.

[0037] Step 2.4, calculate the frequency shift δf of the end comb teeth in the acoustic frequency comb image using the following formula. end : δf end =f end (p)-f end (p0); Where: f end (p) represents the frequency value of the last comb tooth furthest from the center frequency in the acoustic frequency comb under the current known air pressure p, and f end (p0) is the initial frequency value of the end comb teeth in the acoustic frequency comb under the known air pressure p is the initial air pressure p0=10Pa; The difference δf end This refers to the frequency shift of the end comb teeth caused by changes in air pressure. By utilizing the correlation between this frequency shift and changes in air pressure, a calibration curve is constructed to achieve air pressure sensing based on the acoustic comb effect.

[0038] Step 2.5, input the known pressure p and the corresponding δf end The data is fitted to obtain the sensing line, and the slope S of the sensing line is determined, which is the sensitivity of the barometric pressure sensor. Step 3, Air Pressure Calculation Step 3.1: Place the barometric pressure sensor in an environment with unknown pressure and apply a constant frequency AC voltage V of Ω to the gate electrode 13. ac Drive the air pressure sensor to obtain an acoustic frequency comb image; Step 3.2: Calculate the frequency shift δf of the end comb teeth in the acoustic frequency comb image under this air pressure, following the steps in Step 2.4. end ; Step 3.3, calculate the air pressure p of the environment where the barometer sensor is located using the following formula. amb : pamb =S*δf end .

[0039] The pressure inside the cavity is measured using a precision barometer. The cavity has a vibration radius R = 3 μm for a two-dimensional thin film 6, a thickness h = 0.65 nm (single layer) for the two-dimensional thin film 6, a depth g = 300 nm for the resonant cavity 2, a pretension n0 = 0.1 N / m for the two-dimensional thin film 6, a driving frequency of 1.0025, and a driving force F = 0.06.

[0040] Steps one through three are all performed inside a vacuum test chamber.

[0041] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the scope of protection of the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, any person skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention within the scope of the technology disclosed in the present invention. These simple modifications are all within the scope of protection of the present invention.

Claims

1. A squeeze-film pressure sensor with sensitivity amplification based on an internal resonant frequency comb, characterized in that, include: A silicon substrate has a silicon dioxide layer thereon, and a resonant cavity, a gas channel, a square cavity, a source electrode, and a drain electrode are provided on the silicon dioxide layer. The resonant cavity and the square cavity are connected through the gas channel. Gate electrodes are deposited on the silicon substrate corresponding to the resonant cavity, the gas channel, and the square cavity. A two-dimensional diaphragm, which is laid on a silicon dioxide layer, covers the rear ends of the source and drain electrodes as well as the resonant cavity; The resonant cavity has source electrodes and drain electrodes on both sides of its front end, and a two-dimensional diaphragm is laid on a silicon dioxide layer, which can cover the resonant cavity and the corresponding source electrodes and drain electrodes on both sides of the resonant cavity.

2. The extrusion diaphragm pressure sensor with sensitivity amplification based on an internal resonant frequency comb according to claim 1, characterized in that, The source electrode and drain electrode have the same structure, each including a square sheet at the front end of the silicon dioxide layer surface and a long strip at the middle of the silicon dioxide layer surface, with the end of the square sheet extending towards the rear end of the silicon dioxide layer to form the long strip.

3. A squeeze-film pressure sensor with sensitivity amplification based on an internal resonant frequency comb according to claim 2, characterized in that, The two-dimensional diaphragm is laid on a silicon dioxide layer and can cover the resonant cavity, as well as the strips of the source electrode and the strips of the drain electrode.

4. A method for measuring air pressure using the extrusion diaphragm pressure sensor according to any one of claims 1-3, characterized in that, Includes the following: Step 1, DC bias adjustment: Step 1.1: Place the pressure sensor inside the vacuum test chamber and simultaneously illuminate the two-dimensional thin film with the detection light source and the excitation light source; Step 1.2, apply a DC bias voltage V to the gate electrode. dc It gradually increases from 0V; Step 1.3: The light intensity of the interference fringes generated by the vibration of the two-dimensional thin film is collected with time by a photodetector. The light intensity signal is converted into an electrical signal by the photodetector and sent to a lock-in amplifier for spectrum analysis to obtain the amplitude-frequency response curve. Step 1.4, during the DC bias adjustment process, until the harmonic relationship between the first-order resonant frequency ω and the second-order resonant frequency ω of the two-dimensional thin film in the obtained amplitude-frequency response curve is as follows: At that time, the DC bias voltage adjustment is completed; Step 2: Calibrate the sensitivity of the barometric pressure sensor: Step 2.1: Apply an increasing AC voltage to the gate electrode until the obtained amplitude-frequency response curve changes from a single-peak shape to a symmetrical double-peak shape; the AC voltage at this time is denoted as the target AC voltage, and at this time, the first-mode amplitude-frequency curve and the second-mode amplitude-frequency curve have an intersection region, and the frequency range corresponding to this region is the bifurcation quasi-static region. Step 2.2, Confirmation of the fixed-frequency excitation frequency Ω: Step 2.21: Control the reference frequency of the lock-in amplifier to the quasi-static region. Perform a frequency sweep analysis within this range to obtain the amplitude-frequency response curve. The frequency value corresponding to the lowest point of the dip in the middle of the first-order mode amplitude-frequency curve is f. d The frequency value corresponding to the highest point of the bulge in the middle of the second-order mode amplitude-frequency curve is f. p Record f d to f p All frequency points, including the endpoints; Step 2.22: Retain frequency points with amplitude fluctuations less than 5% from all frequency points as candidate frequency points, where the amplitude fluctuation of a frequency point = (amplitude of that frequency point - average amplitude of all frequency points) ÷ average amplitude of all frequency points * 100%; Step 2.23: Apply AC voltages at each candidate frequency point to the gate electrode, and collect the current signal output from the drain electrode each time a different frequency AC voltage is applied. Send the current signal to the lock-in amplifier, and the lock-in amplifier will perform spectral analysis on the current signal to obtain the acoustic frequency comb image. Step 2.24: Select the acoustic frequency comb image that meets the following conditions from each acoustic frequency comb image as the candidate acoustic frequency comb image: A. The spacing deviation between any two adjacent comb teeth is <1%, where the spacing deviation between two adjacent comb teeth = (the spacing between two adjacent comb teeth - the average spacing of all comb teeth) ÷ the average spacing of all comb teeth * 100%; B. The difference between the amplitude corresponding to the frequency of the main comb tooth and the amplitude corresponding to the frequency of the comb teeth on both sides is >10dB; C. Each time an AC voltage of a certain frequency is applied to the gate electrode, the process must be repeated multiple times, and the resulting acoustic frequency comb image is the same each time. Step 2.25: Among the obtained candidate acoustic frequency comb images, select the candidate acoustic frequency comb image with the most comb teeth and the largest amplitude corresponding to the main comb teeth as the target acoustic frequency comb image, and the frequency of the AC voltage applied to it is the fixed frequency excitation frequency Ω. Step 2.3: Conduct a pressure calibration experiment and establish a pressure-frequency comb response model. Under different known air pressures, a constant frequency AC voltage V is applied to the gate electrode. ac , thus obtaining the acoustic frequency comb image; Step 2.4, calculate the frequency shift δf of the end comb teeth in the acoustic frequency comb image using the following formula. end : δf end =f end (p)-f end (p0) Where: f end (p) represents the frequency value of the end teeth of the acoustic frequency comb under the current known air pressure p, and f end (p0) is the initial frequency value of the end comb teeth in the acoustic frequency comb under the known air pressure p is the initial air pressure p0=10Pa; Step 2.5, input the known pressure p and the corresponding δf end The data is fitted to obtain a sensing line, and the slope S of the sensing line is determined, which is the sensitivity of the barometric pressure sensor. Step 3, Air Pressure Calculation Step 3.1: Place the barometric pressure sensor in an environment with unknown pressure and apply a constant frequency AC voltage V to the gate electrode. ac Drive the air pressure sensor to obtain an acoustic frequency comb image; Step 3.2, following the steps, calculate the frequency shift δf of the end comb teeth in the acoustic frequency comb image under this air pressure. end ; Step 3.3, calculate the air pressure p of the environment where the barometer sensor is located using the following formula. amb : p amb =S*δf end 。 5. The method according to claim 4, characterized in that, Steps one through three are all performed inside a vacuum test chamber.

6. A method for manufacturing the extrusion diaphragm pressure sensor according to any one of claims 1-3, characterized in that, Includes the following: Step 1: Take a silicon wafer as the silicon substrate, grow a silicon dioxide layer on it through thermal oxidation process, and pattern the silicon dioxide layer through photolithography process to etch out the resonant cavity, gas channel and square cavity. Step 2: Spin-coat photoresist onto the silicon dioxide layer after photolithography, and use a mask to pattern the source electrode, drain electrode, and gate electrode. Step 3: Sputter Cr metal layer and Au metal layer sequentially on the patterned silicon dioxide layer, remove the photoresist, and obtain the source electrode, drain electrode, and gate electrode. Step four involves transferring the two-dimensional diaphragm onto the resonant cavity, source electrode, drain electrode, and silicon dioxide layer. The resonant cavity between the two-dimensional diaphragm and the silicon dioxide layer forms a suspended drum-shaped structure, thus completing the fabrication of the pressure sensor.

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