A beam resonator vacuum degree monitoring device working at a nonlinear flexion point

Abstract

The utility model provides a kind of beam resonator vacuum degree monitoring device working at nonlinear buckling point, belong to micro electro mechanical system technical field.Monitoring device includes electrode block, vibrating beam, drive electrode and inductive electrode.Vibrating beam is provided with electrode block along the both ends of its own axial direction, electrode block exerts mechanical axial compressive stress to vibrating beam, electrode block exerts direct current to vibrating beam to make it thermal expansion.Electrode block can constrain vibrating beam, so that axial thermal compressive stress is generated.Vibrating beam stiffness is reduced under the superimposed action of axial thermal compressive stress and mechanical axial compressive stress, so that the resonant frequency of vibrating beam is reduced, also make vibrating beam more sensitive to the change of vacuum degree.When vacuum degree reaches threshold value, the resonant frequency of vibrating beam is same with the excitation frequency of drive electrode, trigger the action of vacuum degree switch corresponding to monitoring device.The utility model can actively adjust drive frequency to realize programmable adjustment of vacuum degree threshold value, to improve the versatility of monitoring device.

Description

Technical Field

[0001] This utility model relates to the field of microelectromechanical systems (MEMS) technology, and in particular to a vacuum monitoring device for a beam resonator operating at a nonlinear buckling point. Background Technology

[0002] Currently, in technological fields such as semiconductor manufacturing, aerospace, and particle physics experiments, the stability of high-vacuum environments directly determines production yield, equipment safety, and experimental accuracy. Vacuum switches, as core components for "vacuum threshold discrimination and system protection" in this environment, have their performance becoming a key factor restricting technological upgrades in these fields. Specifically, when the vacuum level reaches a preset safety threshold, the vacuum switch must respond quickly and trigger control commands to prevent defects in semiconductor wafers due to pressure fluctuations, malfunctions in spacecraft components due to abnormal vacuum levels, or data distortion in particle physics experiments due to pressure deviations. Therefore, vacuum switches must simultaneously meet the core requirements of high sensitivity, long lifespan, and adaptability to high-vacuum environments.

[0003] Currently, mainstream vacuum switches are mainly divided into two categories: one is the mechanical contact vacuum switch, which relies on the deformation of elastic elements (such as spring diaphragms) to drive the mechanical contacts to close / open and achieve the switching function. However, this type of switch has inherent defects: in high vacuum environments, the mechanical contacts are prone to arcing due to the desorption of adsorbed gas on the surface, resulting in mechanical wear. Therefore, its service life is usually less than 100,000 cycles, which is difficult to meet the long-term stable monitoring needs of fields such as semiconductor manufacturing. The other is the non-contact vacuum switch, which is mainly based on traditional MEMS (Micro-Electro-Mechanical System) capacitive switches. Although it avoids the mechanical contact problem, it is limited by structural design. Capacitive switches rely on changes in the electrode spacing. Under high vacuum, the dielectric constant is stable but the sensitivity is low, making it difficult to adapt to the differentiated monitoring needs of different scenarios.

[0004] In recent years, MEMS resonant vacuum switches have become a research hotspot due to their potential for higher sensitivity than traditional non-contact switches, as they achieve signal conversion based on resonant frequency changes. However, related MEMS resonant vacuum switches still face technical bottlenecks: On the one hand, in high vacuum environments, gas molecule density is extremely low, and the mean free path (λ) of gas molecules is much larger than the characteristic size of the resonant structure. Molecules change from "continuous collisions" to "sparse collisions," and the gas damping effect almost disappears. The damping force no longer fluctuates significantly with changes in gas pressure. At this time, the vibration of the resonant structure is mainly dominated by internal damping and radiation damping. The quality factor of traditional resonant structures decays, resulting in a decrease in the signal-to-noise ratio of the resonant frequency signal, making it difficult to accurately capture the frequency changes corresponding to the gas pressure threshold. On the other hand, related MEMS resonant vacuum switches cannot achieve programmable adjustment of the vacuum threshold, which limits the versatility of the devices. Utility Model Content

[0005] This invention provides a vacuum monitoring device for a beam resonator operating at a nonlinear buckling point. The purpose is to enable the monitoring device to actively adjust the axial thermocompression stress of the vibrating beam to improve the sensitivity of vacuum change detection. Furthermore, by actively adjusting the driving frequency of the AC signal applied by the driving electrode, the vacuum threshold can be programmably adjusted to improve the versatility of the monitoring device.

[0006] To achieve the above objectives, this utility model provides a vacuum degree monitoring device for a beam resonator operating at a nonlinear buckling point, located in a vacuum environment. The monitoring device includes: Electrode blocks; The vibrating beam has electrode blocks at both ends along its axial direction. The electrode blocks can apply mechanical axial compressive stress to the vibrating beam, apply direct current to the vibrating beam to cause thermal expansion, and constrain the vibrating beam to cause axial thermocompressive stress. Under the superposition of the axial thermocompressive stress and the mechanical axial compressive stress, the stiffness of the vibrating beam decreases, thereby reducing the resonant frequency of the vibrating beam and increasing the proportion of the influence of the vacuum degree of the environment in which the vibrating beam is located on the resonant frequency of the vibrating beam. A driving electrode is configured to excite the vibrating beam to vibrate. The sensing electrode is configured to monitor the vibration amplitude of the vibrating beam and convert it into an electrical signal; When the vacuum level reaches the threshold, the resonant frequency of the vibrating beam is the same as the excitation frequency of the driving electrode, thereby triggering the vacuum switch corresponding to the monitoring device to open.

[0007] In one embodiment, the axial thermal stress of the vibrating beam is positively correlated with the magnitude of the direct current, so that the resonant frequency of the vibrating beam is negatively correlated with the magnitude of the direct current. The resonant frequency of the vibrating beam has a minimum critical value. When the resonant frequency of the vibrating beam approaches the minimum critical value, the rate of change of the resonant frequency of the vibrating beam has a maximum value.

[0008] In one embodiment, the monitoring device further includes a pressure component disposed on the side of the electrode block away from the vibrating beam. The pressure component applies mechanical axial compressive stress to the vibrating beam through the pressure difference between its internal structure and the vacuum environment.

[0009] In one embodiment, the pressure assembly includes a sealed housing and an elastic deformable membrane, the electrode block is connected to the elastic deformable membrane, the housing and the elastic deformable membrane enclose a sealed cavity, and the pressure inside the sealed cavity is atmospheric pressure.

[0010] In one embodiment, the geometric center of the electrode block is located on the extension of the central axis of the vibrating beam.

[0011] In one embodiment, the driving electrode and the sensing electrode are respectively disposed on opposite sides of the vibrating beam in the thickness direction.

[0012] In one embodiment, the length of the vibrating beam ranges from 200 μm to 1000 μm.

[0013] In one embodiment, the monitoring device further includes a network analyzer and a preamplifier. The network analyzer is electrically connected to the driving electrode so that the driving electrode can excite the vibrating beam to vibrate. The preamplifier is electrically connected to the sensing electrode so as to output the electrical signal of the sensing electrode.

[0014] In one embodiment, the network analyzer is electrically connected to the preamplifier so that the electrical signal of the sensing electrode is amplified and output to the network analyzer to realize real-time measurement of frequency response.

[0015] In one embodiment, the magnitude of the direct current ranges from 0.01 mA to 2 mA.

[0016] The above-mentioned solution of this utility model has the following beneficial effects: In this embodiment, by applying a direct current to the vibrating beam, the beam enters a pre-buckling state under the combined effect of axial thermal compressive stress and mechanical axial compressive stress. By actively adjusting the magnitude of the direct current, and subsequently adjusting the axial thermal compressive stress, the sensitivity of vacuum monitoring is improved. By adjusting the driving frequency of the AC signal applied to the driving electrode to be equal to the resonant frequency corresponding to the desired vacuum threshold, the programmable adjustment of the vacuum threshold can be achieved. Different mechanical axial compressive stress thresholds can correspond to different application scenarios, making the monitoring device of this application highly versatile. Furthermore, by utilizing the nonlinear dynamic characteristics of the vibrating beam ("jump characteristics"), i.e., when the vacuum change reaches the threshold, a nonlinear jump in the amplitude of the vibrating beam is triggered, thereby "turning on" the vacuum switch, eliminating the need for complex frequency tracking systems (such as phase-locked loops and high-speed ADCs) found in traditional technologies. This not only greatly improves sensitivity but also achieves sub-second response, while reducing the size of the monitoring device to ≤2mm. 3 The power consumption is reduced to the microwatt level, making it perfectly suited for compact systems and low-power scenarios. Further integration with device miniaturization and system integration will enable the technical solution presented in this application to precisely serve particle accelerator beam pipes, long-term monitoring of space systems, and next-generation semiconductor manufacturing, driving the iterative upgrade of vacuum monitoring technology.

[0017] Other beneficial effects of this invention will be described in detail in the following detailed description section. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the monitoring device in one embodiment of the present invention; Figure 2 This is a partial structural schematic diagram of the monitoring device in one embodiment of the present invention; Figure 3 This is a schematic diagram of the vibration state of the vibrating beam in one embodiment of the present invention; Figure 4 This is a curve showing the relationship between the resonant frequency of the vibrating beam and the magnitude of the direct current in one embodiment of this utility model; Figure 5 This is a schematic diagram of the binary switch of the vibrating beam in one embodiment of the present invention; Figure 6 This is a curve showing the variation of the resonant frequency of the vibrating beam with ambient air pressure in one embodiment of this utility model.

[0019] [Explanation of Labels in the Attached Image] 1. Electrode block; 2. Vibrating beam; 3. Drive electrode; 4. Sensing electrode; 5. Pressure assembly; 51. Housing; 52. Elastic deformable membrane; 53. Sealed cavity; 6. Network analyzer; 7. Preamplifier. Detailed Implementation

[0020] To make the technical problems, solutions, and advantages of this utility model clearer, a detailed description will be provided below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model. Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0021] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a locking connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0023] This application provides a vacuum monitoring device for a beam resonator operating at a nonlinear buckling point. It aims to utilize the electrothermal effect generated by direct current flowing through the vibrating beam and adjust the magnitude of the direct current to precisely control the axial thermocompressive stress of the vibrating beam, thereby improving the sensitivity of vacuum monitoring. When the monitoring device is in a vacuum environment, the mechanical axial compressive stress and the axial thermocompressive stress form a superposition effect, which reduces the stiffness of the vibrating beam, causing it to gradually approach a pre-buckling state of nonlinear buckling. As the vibrating beam approaches nonlinear buckling, its vibration state undergoes a sudden change at the vacuum threshold, thus achieving high-precision and high-sensitivity identification of the vacuum threshold. Unlike related vacuum switches that rely on "mechanical contact," this application uses the nonlinear transition of the vibrating beam's vibration state as the switching signal for the corresponding vacuum switch. This not only avoids the wear problems caused by mechanical contact and significantly extends the service life of the monitoring device, but also allows for programmable adjustment of the vacuum threshold by adjusting the excitation frequency to the resonant frequency corresponding to the desired vacuum threshold. This application provides a simple, adjustable threshold, and stable and reliable solution for precise pressure monitoring in medium and high vacuum environments. It not only further promotes the miniaturization of devices and the development of system integration, but also has the potential to provide high-sensitivity technical support for vacuum monitoring technology in the semiconductor manufacturing and aerospace industries, and drive the upgrading of monitoring accuracy in related fields.

[0024] Specifically, please refer to Figure 1 , Figure 2 and Figure 3 The monitoring device of this application is located in a vacuum environment and includes an electrode block 1, a vibrating beam 2, a driving electrode 3, and a sensing electrode 4. It should be noted that the vacuum environment refers to a medium or high vacuum environment.

[0025] Electrode blocks 1 are provided at both ends of the vibrating beam 2 along its own axial direction. For example, the two ends of the vibrating beam 2 along its own axial direction are rigidly connected to the electrode blocks 1 through anchor points, so that the vibrating beam 2 is a double-ended fixed beam. Both the electrode blocks 1 and the vibrating beam 2 can be made of aluminum nitride. The electrode blocks 1 can apply mechanical axial compressive stress to the vibrating beam 2. The electrode blocks 1 can apply direct current to the vibrating beam 2. For example, the electrode blocks 1 can apply a DC bias voltage to the vibrating beam 2 to cause thermal expansion of the vibrating beam 2. The electrode blocks 1 can constrain the deformation of the vibrating beam 2 in its own axial direction, thereby causing the vibrating beam 2 to generate axial thermocompressive stress. Under the superposition of axial thermocompressive stress and mechanical axial compressive stress, the stiffness of the vibrating beam 2 can be reduced, thereby reducing the resonant frequency of the vibrating beam 2 and increasing the proportion of the influence of the vacuum degree of the environment in which the vibrating beam 2 is located on the resonant frequency of the vibrating beam.

[0026] The driving electrode 3 is configured to excite the vibration beam 2 to vibrate in conjunction with a DC bias voltage applied across its two ends. The sensing electrode 4 is configured to monitor the vibration amplitude of the vibration beam 2 and convert it into an electrical signal. Both the driving electrode 3 and the sensing electrode 4 can be made of aluminum nitride.

[0027] For example, electrode block 1 can apply a fixed DC bias voltage V to vibrating beam 2. bias In conjunction with the AC signal (AC) of the driving electrode, an electrostatic driving force is formed, which excites the vibrating beam 2 to vibrate.

[0028] For example, V bias The core function of the bias voltage is to provide the basic electrical conditions for electrostatic drive and signal detection of the MEMS vibrating beam 2 resonator, while also assisting in adjusting the stress state of the device to optimize sensing performance. Specifically, it can be divided into the following three points: 1. Provides DC bias for electrostatic drive. V bias A fixed DC bias voltage is applied to the vibrating beam 2, which, in conjunction with the AC signal (AC) of the driving electrode 3, forms an electrostatic driving force. This electrostatic force excites the vibrating beam 2 to vibrate, which is crucial for the resonator to enter its working state—without V... bias With the provided DC bias, stable electrostatic excitation cannot be generated by AC signal alone, and the vibrating beam 2 cannot achieve resonance.

[0029] 2. Achieve capacitive detection of vibration signals When the vibrating beam 2 vibrates, it changes the gap between itself and the sensing electrode 4, thereby altering the capacitance value. bias The applied DC voltage converts the capacitance change into a measurable AC induced current (motion current), which, after amplification, can be used to analyze key parameters such as resonant frequency and amplitude.

[0030] 3. Assist in adjusting the stress state of the vibrating beam 2 Although V bias While it does not directly generate Joule heating, it can indirectly assist in stress regulation when acting in conjunction with the DC current at the beam anchor points. When the Joule heating generated by the DC current causes the vibrating beam 2 to approach the buckling zone, V bias The stable application of the pressure can ensure that the vibrating beam 2 vibrates under the preset stress state, avoiding stress imbalance caused by fluctuations in electrical conditions.

[0031] When the mechanical axial compressive stress and axial thermocompressive stress are adjusted to minimize the stiffness of the vibrating beam 2, i.e., when the vibrating beam 2 is about to buckle (the position where vacuum monitoring is most sensitive), if the vacuum level remains constant, the resonant frequency of the vibrating beam 2 will be a fixed value. By setting the excitation frequency output by the driving electrode 3 to be equal to this fixed value, the vibrating beam 2 can generate a large vibration. The sensing electrode 4 can detect the vibration amplitude of the vibrating beam 2 at this time and convert it into an electrical signal output to trigger the vacuum level switch corresponding to the monitoring device to open, thereby protecting spacecraft components, semiconductor manufacturing equipment, or particle physics experimental devices equipped with the monitoring device of this application.

[0032] For example, please refer to Figure 5 , Figure 5 The horizontal axis represents the driving frequency of the vibrating beam 2, and the vertical axis represents the amplitude of the vibrating beam 2. Figure 5 The dashed line in the figure represents the response curve of the vibrating beam 2 to the excitation frequency when the vacuum level of the environment in which the vibrating beam 2 is located is equal to 100 mTorr. The horizontal axis corresponding to the peak value is the resonant frequency of the vibrating beam 2 at this time. Figure 5 The solid line in the graph represents the response curve of the vibrating beam 2 to the excitation frequency when the vacuum level of the environment in which the vibrating beam 2 is located is less than 100 mTorr. The horizontal axis corresponding to the peak value is the resonant frequency of the vibrating beam 2 at this time. Figure 5 As shown, when the vacuum level of the environment in which the vibrating beam 2 is located changes, the resonant frequency of the vibrating beam 2 also changes. By adjusting the driving frequency of the driving electrode 3 to equal the resonant frequency, the vacuum level of the environment in which the vibrating beam 2 is located can be set to a new threshold, thus demonstrating the programmability of the vacuum threshold.

[0033] It should be noted that the stiffness of the vibrating beam 2 and the vacuum level of the environment in which the vibrating beam 2 is located are two key factors affecting the resonant frequency of the vibrating beam 2. When the stiffness of the vibrating beam 2 decreases under the superposition of mechanical axial compressive stress and axial thermocompressive stress, the proportion of the influence of the stiffness of the vibrating beam 2 on its own resonant frequency decreases. This, in turn, increases the proportion of the influence of the vacuum level of the environment in which the vibrating beam 2 is located on the resonant frequency of the vibrating beam 2, making the resonant frequency of the vibrating beam 2 more sensitive to changes in vacuum level.

[0034] For example, please refer to Figure 5The frequency response of the vibrating beam 2 is nonlinear. When the driving frequency of the driving electrode 3 reaches the resonant frequency of the vibrating beam 2, the vibration of the vibrating beam 2 will change from low amplitude to high amplitude. The frequency response curve of the vibrating beam 2 shows an upward jump, which can realize the "on" state of the vacuum switch.

[0035] For example, the greater the vacuum level of the environment in which the vibrating beam 2 is located, the fewer gas molecules are around the vibrating beam 2, resulting in less gas damping during the vibration process. Please refer to [link to relevant documentation]. Figure 6 As the ambient air pressure of the vibrating beam 2 gradually increases, that is, the vacuum level of the environment in which the vibrating beam 2 is located gradually decreases, the gas damping of the vibrating beam 2 during vibration gradually increases, which in turn causes the resonant frequency of the vibrating beam 2 to gradually decrease. This is consistent with... Figure 5 The corresponding pattern of change.

[0036] For example, the nonlinear relationship between the deflection of the vibrating beam 2 and the gas damping can be expressed by the following equation:

[0037] In the formula, The effective mass of vibrating beam 2, The gas damping coefficient of the environment in which the vibrating beam 2 is located. The stiffness of vibrating beam 2, These are the coefficients of a third nonlinearity. Let be the deflection of vibrating beam 2. The frequency of the AC drive signal applied to the drive electrode 3 and the sensing electrode 4. For time, The amplitude of the electrostatic driving force.

[0038] For example, when the vacuum threshold is determined, and the magnitude of the direct current is determined to determine the magnitude of the axial thermocompression stress, the total stress applied to the vibrating beam 2 can be determined accordingly, becoming a constant value. Based on this, the resonant frequency of the vibrating beam 2 corresponding to the desired vacuum threshold can be obtained by calculation or testing. The excitation frequency output by the driving electrode 3 is set as the resonant frequency of the vibrating beam 2 at this time.

[0039] For example, when the axial thermal compressive stress and the mechanical axial compressive stress are superimposed, the vibrating beam 2 will buckle from the geometric center when the load on the vibrating beam 2 reaches the critical buckling point.

[0040] For example, the vacuum threshold of the environment in which the vibrating beam 2 is located can be programmed by adjusting the driving frequency, thereby realizing the binary detection of the opening or closing of the corresponding vacuum switch.

[0041] For example, the resonant frequency of the vibrating beam 2 drifts nonlinearly with the increase of DC current. For a given vacuum threshold, simply increasing the DC current will make the vibrating beam 2 most sensitive to vacuum monitoring when the resonant frequency approaches its minimum value.

[0042] In this embodiment, by applying a direct current to the vibrating beam 2, the vibrating beam 2 enters a pre-buckling state under the combined action of axial thermal compressive stress and mechanical axial compressive stress. By actively adjusting the magnitude of the direct current, the axial thermal compressive stress of the vibrating beam 2 is adjusted to improve the sensitivity of vacuum monitoring. By adjusting the driving frequency of the AC signal applied by the driving electrode 3 to be equal to the resonant frequency corresponding to the desired vacuum threshold, the programmable adjustment of the vacuum threshold can be achieved. Different mechanical axial compressive stress thresholds can correspond to different application scenarios, making the monitoring device of this application highly versatile. In addition, by utilizing the nonlinear dynamic characteristics ("jump characteristics") of the vibrating beam 2, that is, when the vacuum change reaches the threshold, a nonlinear jump in the amplitude of the vibrating beam 2 is triggered, thereby "turning on" the vacuum switch, eliminating the need for complex frequency tracking systems (such as phase-locked loops and high-speed ADCs) in traditional technologies. This not only greatly improves the sensitivity but also achieves sub-second response, while reducing the size of the monitoring device to ≤2mm. 3 The power consumption is reduced to the microwatt level, making it perfectly suited for compact systems and low-power scenarios. Further integration with device miniaturization and system integration will enable the technical solution presented in this application to precisely serve particle accelerator beam pipes, long-term monitoring of space systems, and next-generation semiconductor manufacturing, driving the iterative upgrade of vacuum monitoring technology.

[0043] In one embodiment, please refer to Figure 4The axial thermocompressive stress of vibrating beam 2 is positively correlated with the magnitude of the direct current, while the resonant frequency of vibrating beam 2 is negatively correlated with the magnitude of the direct current. That is, as the magnitude of the direct current gradually increases, there is a minimum critical value for the resonant frequency of vibrating beam 2. When the resonant frequency of vibrating beam 2 approaches the minimum critical value, the rate of change of the resonant frequency of vibrating beam 2 reaches its maximum value. Applying direct current to vibrating beam 2 allows it to operate in a pre-buckling state. Mechanical axial compressive stress can also reduce the stiffness of vibrating beam 2 and change its resonant frequency. Different magnitudes of direct current result in different resonant frequencies of vibrating beam 2, from which a relationship curve can be generated. Based on this relationship curve, the point where the resonant frequency of vibrating beam 2 changes most rapidly with current can be identified. This point can be defined as the sensitive point. Near this sensitive point, vibrating beam 2 is very sensitive to changes in vacuum. Both axial thermocompressive stress and mechanical axial compressive stress are loads on vibrating beam 2, and vibrating beam 2 is very sensitive to changes in vacuum near the sensitive point. The magnitude of the DC current at the sensitive point is fixed, meaning that the change in the resonant frequency of the vibrating beam 2 due to the axial thermal stress is fixed. At this point, as long as the vacuum level reaches the threshold, the vibrating beam 2 can generate a large vibration under the excitation of the driving electrode 3, thereby triggering the vacuum level switch action.

[0044] like Figure 4 As shown, as the direct current gradually increases, the resonant frequency of the vibrating beam 2 initially decreases nonlinearly, and the rate of decrease accelerates. When the direct current reaches the critical value for buckling of the vibrating beam 2, the resonant frequency reaches its minimum. When the direct current of the vibrating beam 2 is adjusted to be close to but not yet at the critical value, the monitoring device exhibits maximum sensitivity, which can be more than 20 times greater than when the direct current is zero (when the vibrating beam 2 has not buckled). When the direct current exceeds the critical value, the vibrating beam 2 buckles, forming an arc shape. At this point, the stiffness of the arc-shaped vibrating beam 2 increases with increasing curvature, and the resonant frequency of the vibrating beam 2 increases with increasing direct current. However, the sensitivity is lower than the maximum sensitivity before the critical value and hardly changes further.

[0045] In one embodiment, please refer to Figure 1The monitoring device also includes a pressure component 5, which is disposed on the side of the electrode block 1 opposite to the vibrating beam 2. The pressure component 5 applies mechanical axial compressive stress to the vibrating beam 2 through the pressure difference between its internal structure and the vacuum environment. The pressure difference between the internal pressure of the pressure component 5 and the pressure in the medium-high vacuum environment applies pressure to both ends of the vibrating beam 2. That is, the mechanical axial compressive stress is represented by the pressure difference between the internal pressure of the pressure component 5 and the pressure in the medium-high vacuum environment, making the structure of the monitoring device of this application relatively simple. Furthermore, applying mechanical axial compressive stress to both ends of the vibrating beam 2 can also reduce the magnitude of the direct current applied to the vibrating beam 2, which is beneficial to reducing the power consumption of the monitoring device of this application. Therefore, the mechanical axial compressive stress mainly serves to reduce the current required for the vibrating beam 2 to reduce its stiffness to the minimum value before buckling.

[0046] In one embodiment, please refer to Figure 3 The pressure component 5 includes a sealed housing 51 and an elastic deformable membrane 52. The housing 51 can be made of silicon. The elastic deformable membrane 52 can be made of aluminum. The electrode block 1 is connected to the elastic deformable membrane 52. The housing 51 and the elastic deformable membrane 52 enclose a sealed cavity 53, and the pressure inside the sealed cavity 53 is atmospheric pressure. For example, the sealed cavity 53 can be filled with nitrogen. For example, the pressure inside the sealed cavity 53 is one standard atmosphere. In this embodiment, the pressure inside the sealed cavity 53 is normal pressure, while the environment of the monitoring device is a medium-high vacuum environment. The pressure difference inside and outside the sealed cavity 53 causes the elastic deformable membrane 52 to bulge, thereby applying mechanical axial compressive stress to both ends of the vibrating beam 2, making the structure of the monitoring device of this application relatively simple.

[0047] In one embodiment, please refer to Figure 2 The geometric center of electrode block 1 is located on the extension line of the central axis of vibration beam 2, so that uniform axial thermocompression stress can be formed during the process of DC current passing through vibration beam 2.

[0048] In one embodiment, please refer to Figure 1 , Figure 2 and Figure 3 The driving electrode 3 and the sensing electrode 4 are respectively disposed on opposite sides of the vibrating beam 2 in the thickness direction, making the structure of the monitoring device relatively compact. For example, the length directions of the driving electrode 3 and the sensing electrode 4 are both arranged parallel to the length direction of the vibrating beam 2, and the driving electrode 3 and the sensing electrode 4 are both 3 μm away from the vibrating beam 2.

[0049] In one embodiment, the length of the vibrating beam 2 ranges from 200 μm to 1000 μm, making the overall size of the monitoring device relatively small. This allows the monitoring device of this application to be applied in small-scale medium-to-high vacuum environments. For example, the ratio of the length, width, and height of the vibrating beam 2 can be 400:25:3.

[0050] In one embodiment, please refer to Figure 1 The monitoring device also includes a network analyzer 6 and a preamplifier 7. The network analyzer 6 is electrically connected to the drive electrode 3, enabling the drive electrode 3 to apply an AC signal to stimulate the vibration beam 2 to vibrate in conjunction with a DC bias voltage across the vibrating beam 2. For example, the network analyzer 6 could be a Keysight E5061B. The preamplifier 7 is electrically connected to the sensing electrode 4 to output the electrical signal from the sensing electrode 4. For example, the preamplifier 7 could be a PVA560.

[0051] In one embodiment, please refer to Figure 1 The network analyzer 6 is electrically connected to the preamplifier 7 so that the electrical signal of the sensing electrode 4 can be amplified and output to the network analyzer 6, so that the network analyzer 6 can measure the vibration frequency of the vibrating beam 2 in real time.

[0052] In one embodiment, the magnitude of the direct current is in the range of 0.01mA to 2mA, which can raise the temperature of the vibrating beam 2 by 5K to 150K, generating an axial thermocompressive stress of 20MPa to 600MPa, so that the magnitude of the axial thermocompressive stress has a large range.

[0053] The above are preferred embodiments of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A vacuum degree monitoring device for a beam resonator operating at a nonlinear buckling point, characterized in that, Located in a vacuum environment, the monitoring device includes: Electrode blocks; The vibrating beam has electrode blocks at both ends along its axial direction. The electrode blocks can apply mechanical axial compressive stress to the vibrating beam, apply direct current to the vibrating beam to cause thermal expansion, and constrain the vibrating beam to cause axial thermocompressive stress. Under the superposition of the axial thermocompressive stress and the mechanical axial compressive stress, the stiffness of the vibrating beam decreases, thereby reducing the resonant frequency of the vibrating beam and increasing the proportion of the influence of the vacuum degree of the environment in which the vibrating beam is located on the resonant frequency of the vibrating beam. A driving electrode is configured to excite the vibrating beam to vibrate. The sensing electrode is configured to monitor the vibration amplitude of the vibrating beam and convert it into an electrical signal; When the vacuum level reaches the threshold, the resonant frequency of the vibrating beam is the same as the excitation frequency of the driving electrode, thereby triggering the vacuum switch corresponding to the monitoring device to open.

2. The vacuum degree monitoring device for a beam resonator operating at a nonlinear buckling point according to claim 1, characterized in that, The axial thermal stress of the vibrating beam is positively correlated with the magnitude of the direct current, so that the resonant frequency of the vibrating beam is negatively correlated with the magnitude of the direct current. The resonant frequency of the vibrating beam has a minimum critical value. When the resonant frequency of the vibrating beam approaches the minimum critical value, the rate of change of the resonant frequency of the vibrating beam has a maximum value.

3. The vacuum monitoring device for a beam resonator operating at a nonlinear buckling point according to claim 1, characterized in that, The monitoring device also includes a pressure component, which is disposed on the side of the electrode block away from the vibrating beam. The pressure component applies mechanical axial compressive stress to the vibrating beam through the pressure difference between its internal structure and the vacuum environment.

4. The vacuum degree monitoring device for a beam resonator operating at a nonlinear buckling point according to claim 3, characterized in that, The pressure assembly includes a sealed housing and an elastic deformable membrane. The electrode block is connected to the elastic deformable membrane. The housing and the elastic deformable membrane enclose a sealed cavity, and the pressure inside the sealed cavity is atmospheric pressure.

5. The vacuum degree monitoring device for a beam resonator operating at a nonlinear buckling point according to claim 1, characterized in that, The geometric center of the electrode block is located on the extension of the central axis of the vibrating beam.

6. The vacuum degree monitoring device for a beam resonator operating at a nonlinear buckling point according to claim 1, characterized in that, The driving electrode and the sensing electrode are respectively disposed on opposite sides of the vibrating beam in the thickness direction.

7. The vacuum degree monitoring device for a beam resonator operating at a nonlinear buckling point according to claim 1, characterized in that, The length of the vibrating beam ranges from 200μm to 1000μm.

8. The vacuum degree monitoring device for a beam resonator operating at a nonlinear buckling point according to claim 1, characterized in that, The monitoring device further includes a network analyzer and a preamplifier. The network analyzer is electrically connected to the driving electrode so that the driving electrode can excite the vibrating beam to vibrate. The preamplifier is electrically connected to the sensing electrode so as to output the electrical signal of the sensing electrode.

9. The vacuum degree monitoring device for a beam resonator operating at a nonlinear buckling point according to claim 8, characterized in that, The network analyzer is electrically connected to the preamplifier so that the electrical signal of the sensing electrode is amplified and output to the network analyzer to realize real-time measurement of frequency response.

10. The vacuum degree monitoring device for a beam resonator operating at a nonlinear buckling point according to any one of claims 1 to 9, characterized in that, The magnitude of the direct current is in the range of 0.01mA to 2mA.

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