Vacuum gauge suitable for high vacuum measurement and preparation method thereof

Abstract

The application discloses a vacuum gauge suitable for high-vacuum measurement, comprising a cap layer, a resonant structure layer and a bottom electrode layer arranged in sequence from top to bottom, wherein a gas film gap structure is arranged between the cap layer and the resonant structure layer, the height of the gas film gap structure is 0.2-4 microns, a capacitor gap structure is arranged between the resonant structure layer and the bottom electrode layer, and the height of the capacitor gap structure is 1-15 microns. The preparation method comprises the following steps: step 1, raw material cleaning; step 2, wafer splitting induction; step 3, cap layer gas film gap structure preparation; step 4, resonant structure layer processing and lower surface metallization; step 5, bottom electrode layer capacitor gap structure preparation and upper surface metallization; step 6, three-layer structure bonding; and step 7, wafer splitting. The application can realize gas film gap and capacitor gap decoupling, is conducive to taking into account extremely small gas film gap and relatively large capacitor gap, and is expected to expand the lower limit of vacuum gauge measurement.

Description

Technical Field

[0001] This invention relates to the technical field of measuring equipment and its preparation method, and particularly to a method suitable for high vacuum (generally 10). - ¹~10 -5 Vacuum gauge for Pa measurement and its preparation method. Background Technology

[0002] Vacuum gauges are the core components of vacuum measuring instruments and are widely used in various scenarios that require precise vacuum monitoring.

[0003] Chinese Patent CN111595511A discloses a full-range vacuum gauge and its testing method. Based on a silicon-based material, it uses a butterfly-shaped vacuum gauge sensing element and employs frequency measurement, quality factor measurement, and different mode measurements using the same sensing element to achieve a wide-range measurement capability with high resolution. In the structural design, gas damping enhancement under high vacuum is achieved through methods such as adjusting the pressure film damping area and the gas film gap. Simultaneously, utilizing the advantage of low thermoelastic damping in the bending torsion mode, the bending torsion mode is used as the high-vacuum detection mode to achieve 1E-3Pa (i.e., 10...). -3 The lower limit of linear measurement is 1E-5 Pa (i.e., 10 Pa). However, commercial vacuum gauges need to achieve this. -5 Existing butterfly-shaped vacuum gauges have two main shortcomings that limit the expansion of the measurement lower limit, even to vacuum levels below 100 Pa (Pa). Firstly, butterfly-shaped vacuum gauges are made of silicon-based materials, and the influence of silicon's thermal expansion coefficient makes it difficult to further improve the quality factor of the resonant structure. Secondly, the significant capacitive nonlinearity caused by the extremely small gas film gap limits further improvement in the resonant amplitude and also introduces a large measurement error. The impact of capacitive nonlinearity on the resonant amplitude is as follows: Figure 1 As shown. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a vacuum gauge suitable for high vacuum measurement that can decouple the gas film gap and the capacitor gap, which is beneficial to taking into account both the extremely small gas film gap and the large capacitor gap, and is expected to expand the measurement lower limit of the vacuum gauge.

[0005] The present invention further provides a method for preparing the above-mentioned vacuum gauge.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A vacuum gauge suitable for high vacuum measurement includes a cap layer, a resonant structure layer, and a bottom electrode layer arranged sequentially from top to bottom. A gas film gap structure with a height of 0.2 to 4 μm is provided between the cap layer and the resonant structure layer. A capacitor gap structure with a height of 1 to 15 μm is provided between the resonant structure layer and the bottom electrode layer.

[0007] As a further improvement to the above technical solution: a first pit is provided on the lower surface of the cap layer, and the first pit forms the air film gap structure after the cap layer is bonded to the resonant structure layer.

[0008] As a further improvement to the above technical solution: a first metal film layer is provided on the lower surface of the resonant structure layer, a second pit is provided on the upper surface of the bottom electrode layer, and a second metal film layer is provided on the surface of the second pit. After the resonant structure layer and the bottom electrode layer are bonded, the first metal film layer and the second metal film layer form a capacitor for driving and signal detection of the resonant structure layer.

[0009] As a further improvement to the above technical solution: the second pit has a gas channel on at least one side, through which external gas molecules enter the interior and interact with the resonant structure layer.

[0010] As a further improvement to the above technical solution: the resonant structure layer includes bonding anchor points, a resonant beam, and a mass block, and the first metal film layer is uniformly distributed on the resonant beam and the mass block and the signal is led out through the electrode on the bonding anchor point.

[0011] As a further improvement to the above technical solution: the resonant structure layer is a single-bonded anchor point, a single resonant beam, and a single mass block structure; or a double-bonded anchor point, a three-resonant beam, and a double mass block structure; or a double-bonded anchor point, a double resonant beam, and a single mass block structure; the resonant structure layer operates in the torsional oscillation mode of the resonant beam.

[0012] As a further improvement to the above technical solution: the cap layer, the resonant structure layer and the bottom electrode layer are all made of fused silica material.

[0013] As a further improvement to the above technical solution: the thickness of the cap layer is 0.2-2mm, the thickness of the resonant structure layer is 0.03-0.5mm, and the thickness of the bottom electrode layer is 1-5mm.

[0014] As a further improvement to the above technical solution: the capping layer and the resonant structure layer, as well as the resonant structure layer and the bottom electrode layer, are bonded together through a hydrogen-oxygen catalytic bonding process.

[0015] A method for preparing a vacuum gauge suitable for high vacuum measurement as described above includes the following steps: Step 1: Cleaning raw materials; Step 2: Wafer cleavage induction; Step 3: Preparation of the air film gap structure in the capping layer; Step 4: Fabrication of the resonant structure layer and metallization of the lower surface; Step 5: Fabrication of the capacitor gap structure in the bottom electrode layer and metallization of the upper surface; Step 6: Three-layer bonding; Step 7: Wafer dicing.

[0016] Compared with the prior art, the advantages of the present invention are as follows: This invention discloses a vacuum gauge suitable for high-vacuum measurements. A cap layer serves as a protective structure for the bottom electrode layer, a resonant structure layer acts as a gas-damped sensitive layer, and the bottom electrode layer supports the resonant structure layer. A gas film gap structure is provided between the cap layer and the resonant structure layer, and a capacitor gap structure is provided between the resonant structure layer and the bottom electrode layer. These gas film gap and capacitor gap structures are distributed on the upper and lower sides of the resonant structure layer, achieving decoupling between the gas film gap and the capacitor gap. This ensures a minimal gas film gap to enhance the gas pressure film damping sensitivity, while also guaranteeing a large capacitor gap to prevent capacitive nonlinear errors. This vacuum gauge, suitable for high-vacuum measurements, is adapted to miniaturized, high-precision vacuum detection scenarios and can be widely used in equipment support, deep space exploration, semiconductor physics, and other fields.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating the effect of capacitor nonlinearity on the resonance amplitude.

[0019] Figure 2 This is a three-dimensional structural diagram of the cap layer in this invention.

[0020] Figure 3 This is a schematic diagram of the resonant structure layer in this invention, where (a) is the upper surface and (b) is the lower surface.

[0021] Figure 4 This is a schematic diagram of the bottom electrode layer in this invention.

[0022] Figure 5 This is a three-dimensional structural schematic diagram of the vacuum gauge applicable to high vacuum measurement according to the present invention.

[0023] Figure 6 This is a schematic flowchart illustrating the preparation method of the vacuum gauge applicable to high vacuum measurement according to the present invention.

[0024] The labels in the diagram represent: 1. Cap layer; 11. First recess; 2. Resonant structure layer; 21. First metal film layer; 22. Bonding anchor point; 23. Resonant beam; 24. Mass block; 3. Bottom electrode layer; 31. Second recess; 32. Second metal film layer; 100, Cap layer wafer; 101, First wafer pit; 103, First wafer chromium layer; 200, Resonant structure layer wafer; 204, First wafer metal electrode; 300, Bottom electrode layer wafer; 301, Second wafer pit; 302, Second wafer metal electrode; 303, Second wafer chromium layer; 401, Split groove; Detailed Implementation In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] like Figures 2 to 5As shown, to extend the measurement limit of vacuum gauges, this invention proposes a vacuum gauge suitable for high vacuum measurements. Compared with existing technologies, the vacuum gauge for high vacuum measurements in this embodiment mainly includes two improvements: firstly, it is made of fused silica material, which helps overcome the bottleneck of the thermoelastic damping of silicon-based materials on the measurement limit; secondly, a resonant structure with decoupled gas film gap and capacitor gap is designed, effectively suppressing the influence of capacitive nonlinearity. Based on the above two improvements, it is expected to extend the measurement limit of the butterfly-type vacuum gauge to 1E-5Pa.

[0029] In terms of quality factor suppression, when the inherent damping loss of the resonator can be ignored compared to the gas damping loss, the expression for the quality factor is:

[0030] in, , , , , These represent gas damping loss, anchor point loss, thermoelastic damping loss, surface loss, and other losses, respectively. This represents the combination of all losses except for gas damping losses. P d This represents the lower limit of the gas pressure sensitive to the quality factor of the harmonic oscillator, corresponding to the lower limit of the vacuum pressure that the harmonic oscillator can measure. When >> When the quality factor is linearly related to the gas pressure, vacuum pressure can be measured by measuring the quality factor of the harmonic oscillator.

[0031] To improve the sensitivity of the resonator to vacuum pressure and extend the lower limit of vacuum pressure measurement, it is necessary to improve the gas pressure film damping sensitivity of the resonator while reducing inherent damping losses. The ultimate goal of both strategies is to increase the proportion of gas damping in the total damping under high vacuum conditions. Vacuum gauges reflect vacuum through their quality factor, which can be expressed by decay time or resonance amplitude. With vacuum pressure The relationship and resonance amplitude With vacuum pressure The relationship is represented as:

[0032]

[0033] in, T It is the ambient temperature. R It is the gas constant. M m It is the molecular molar constant. L ,W , d 0 represents the length, width, and air film gap of the resonant structure, respectively. On the one hand, it is necessary to increase the length and width of the resonant structure and decrease the air film gap. d 0 is achieved.

[0034] When the gas damping loss is small, the thermoelastic damping loss is the main factor determining the upper limit of the quality factor of the resonant structure. On the other hand, it is necessary to use high-quality materials to replace monocrystalline silicon to overcome the constraint of the thermoelastic damping loss of the resonant structure, that is, to reduce the inherent damping loss.

[0035] However, reducing the capacitor spacing introduces significant capacitive nonlinearity, limiting further increases in vibration amplitude. The electrostatic driving force is:

[0036] In the formula The amplitude of the harmonic oscillator. For air film gap, V dc It is the electrostatic drive voltage. C d The initial capacitance is proportional to the size of the resonant structure and inversely proportional to the electrode spacing of the resonant structure.

[0037] Vibration amplitudes are large under high vacuum, and the amplitude-frequency response is no longer a single-valued function. Nonlinear vibration systems exhibit a "stiffening" phenomenon. To avoid capacitive nonlinear effects, the air-film gap needs to be maximized. d 0, which is consistent with the reduction of air film gap described above. d Achieving gas damping sensitization is contradictory.

[0038] In this invention, a design scheme for decoupling the gas film gap and the electrode spacing is proposed. Based on this scheme, it is possible to ensure that the gas film gap is extremely small to increase the gas pressure film damping sensitivity characteristics, and it is also possible to ensure a large capacitor gap to prevent capacitor nonlinearity error.

[0039] The vacuum gauge proposed in this invention, suitable for high vacuum measurement, comprises three parts: a cap layer 1, a resonant structure layer 2, and a bottom electrode layer 3. A gas film gap structure with a height between 0.2 and 4 μm exists between the cap layer 1 and the resonant structure layer 2. This structure is fabricated on the lower surface of the cap layer 1 using inductively coupled plasma etching or wet etching. The resonant structure is a resonant mass block 24 supported by bonding anchor points 22 and resonant beams 23. It can be a single anchor point, single beam, single mass block structure, or a double anchor point, three beams, double mass block structure, or a double anchor point, double beam, single mass block structure. The resonant structure operates in the torsional oscillation mode of the resonant beam 23. A capacitor gap structure with a height between 1 and 15 μm exists between the resonant structure layer 2 and the bottom electrode layer 3. This capacitor gap structure is fabricated on the upper surface of the bottom electrode layer 3 using inductively coupled plasma etching or wet etching.

[0040] Preferably, a capacitor is formed between the first metal film layer 21 on the lower surface of the resonant structure layer 2 and the second metal film layer 32 on the upper surface of the bottom electrode layer 3, and the driving and motion detection of the resonant structure are realized by electrostatic driving-capacitive detection.

[0041] Preferably, the resonant structure layer 2 is fabricated using a laser-modified induced assisted wet etching process.

[0042] Preferably, the capping layer 1 and the resonant structure layer 2, and the resonant structure layer 2 and the bottom electrode layer 3 are bonded together using a hydrogen-oxygen catalytic bonding process.

[0043] This invention also proposes a method for preparing a vacuum gauge suitable for high vacuum measurement, comprising the following steps: Step 1: Cleaning raw materials; Step 2: Wafer cleavage induction; Step 3: Preparation of the air film gap structure in the capping layer; Step 4: Fabrication of the resonant structure layer and metallization of the lower surface; Step 5: Fabrication of the electrode gap structure in the bottom electrode layer and metallization of the upper surface; Step 6: Three-layer bonding; Step 7: Wafer dicing.

[0044] Preferably, each wafer is made of fused silica material. Step 2, wafer cleaving induction, uses a Bessel femtosecond laser to induce the cap layer wafer 100, the resonant structure layer wafer 200, and the bottom electrode layer wafer 300 to generate cleaving grooves 401 inside the material. Step 7, wafer cleaving, uses mechanical stress to induce the growth of the cleaving grooves 401 generated in step 2, ultimately separating the devices to form a single sensor chip.

[0045] Preferably, the gas film gap structure is prepared in step 3. First, a first wafer chromium layer 103 with a thickness of 0.1–1.5 μm is deposited by magnetron sputtering on the lower surface of the capping layer wafer 100. Then, after spin coating, photolithography, development, chromium etching, and resist removal, a capping layer wafer 100 with a mask protection on the lower surface is prepared. Next, a first wafer pit 101 with a depth of 0.2–4 μm is etched on the lower surface of the capping layer wafer 100 using inductively coupled plasma etching or wet etching. Finally, the metal mask on the lower surface of the capping layer wafer 100 is removed using wet etching. Preferably, step 4 involves the fabrication of the resonant structure layer and the metallization of its lower surface. First, a femtosecond laser is used to induce modification of the resonant structure layer wafer 200, and the resonant structure is released through a wet etching process. Then, a magnetron sputtering film is deposited on the lower surface of the resonant structure, and the film is a single-component film or a multi-component combination film selected from Cr, Ti, Ag, Ni, Al, and Au. Finally, through steps of spraying adhesive, photolithography, development, metal etching, and photoresist removal, the metal film on the lower surface of the resonant structure layer wafer 200 is patterned to prepare the first wafer metal electrode 204 of the required size.

[0046] Preferably, step 5 involves the fabrication of the electrode gap structure of the bottom electrode layer and the metallization of its upper surface. First, a second wafer chromium layer 303 with a thickness between 0.1 and 1.5 μm is deposited on the upper surface of the bottom electrode layer wafer 300 by magnetron sputtering. After spin coating, photolithography, development, chromium etching, and resist removal, an etched protective layer is prepared. Then, a second wafer pit 301 with a depth of 1 to 15 μm is etched on the upper surface of the bottom electrode layer wafer 300 using inductively coupled plasma etching or wet etching. The metal mask on the upper surface of the bottom electrode layer wafer 300 is then removed using wet etching. Finally, the metal film layer on the upper surface of the bottom electrode layer wafer 300 is patterned through spin coating, photolithography, development, metal etching, and photoresist removal steps to prepare the second wafer metal electrode 302 of the required size.

[0047] Preferably, step 6 involves the bonding of the three-layer structure. First, a 1%–5% potassium hydroxide solution is applied to the bonding anchor points on the lower surface of the cap layer wafer 100 and the upper surface of the bottom electrode layer wafer 300 using a screen printing process. Then, the three-layer structure is aligned, bonded, and left to stand at room temperature for 24 hours. Finally, under high vacuum (<1E-3Pa) conditions, the three-layer structure is bonded together by high temperature (200–450°C) and high pressure (500–3000N), and a single sensitive element is formed by stress-induced cleavage.

[0048] This vacuum gauge, suitable for high vacuum measurement, has a cap layer 1 serving as a protective structure for the bottom electrode layer 3, a resonant structure layer 2 serving as a gas damping sensitive layer, and a bottom electrode layer 3 serving as a support for the resonant structure layer 2. A gas film gap structure is provided between the cap layer 1 and the resonant structure layer 2, and a capacitor gap structure is provided between the resonant structure layer 2 and the bottom electrode layer 3. The gas film gap structure and the capacitor gap structure are distributed on the upper and lower sides of the resonant structure layer 2, achieving decoupling between the gas film gap and the capacitor gap. This ensures a minimal gas film gap to increase the gas pressure film damping sensitivity, while also guaranteeing a large capacitor gap to prevent capacitive nonlinear errors. It is suitable for miniaturized, high-precision vacuum detection scenarios and can be widely used in equipment support, deep space exploration, semiconductor physics, and other fields.

[0049] Example 1 A vacuum gauge suitable for high vacuum measurement includes a cap layer 1, a resonant structure layer 2, and a bottom electrode layer 3.

[0050] The capping layer wafer 100 is made of fused silica wafer with a thickness of 0.5 mm. Its lower surface has a first wafer pit 101 formed by wet etching with a thickness of 1.2 μm. After the capping layer wafer 100 is bonded to the resonant structure layer wafer 200, the first wafer pit 101 forms a gas film sensitization structure.

[0051] The resonant structure layer wafer 200 is made of fused silica wafer with a thickness of 0.1 mm. Its structure includes bonding anchors, resonant beams and mass blocks. The lower surface of the resonant structure layer wafer 200 has a first wafer metal electrode 204. The outer dimensions of the resonant mass block are consistent with or smaller than the first wafer recess 101. The first wafer metal electrode 204 is uniformly distributed on the resonant mass block and the resonant beam, and the signal is led out through the electrodes on the bonding anchors.

[0052] The bottom electrode layer wafer 300 is made of fused silica wafer with a thickness of 1.5 mm. Its upper surface has a second wafer pit 301 formed by wet etching, with a length and width of 5 mm and 3.2 mm respectively, and a thickness of 15 μm. The surface of the second wafer pit 301 has a second wafer metal electrode 302, whose size and shape match the first wafer metal electrode 204.

[0053] like Figure 6 As shown, a method for preparing a vacuum gauge suitable for high vacuum measurement includes the following steps: The standard cleaning process was used to clean fused silica wafers with thicknesses of 0.5 mm, 0.1 mm, and 1.5 mm (cap layer wafer 100, resonant structure layer wafer 200, and bottom electrode layer wafer 300). Using a Bessel femtosecond laser, cleavage grooves 401 are induced in the modified cap layer wafer 100, the resonant structure layer wafer 200, and the bottom electrode layer wafer 300 according to the external dimensions of each individual device.

[0054] Magnetron sputtering was used to sputter chromium onto the lower surface of the cap layer wafer 100 and the upper surface of the bottom electrode layer wafer 300, with a coating thickness of 1 μm.

[0055] Using a spin-coating photolithography process, photoresist is spin-coated on the lower surface of the cap layer wafer 100 and the upper surface of the bottom electrode layer wafer 300, respectively. The first wafer pit 101 and the second wafer pit 301, which are consistent with the structure of the gas film gap and the electrode spacing, are prepared by photolithography and development, with depths of 1.5μm and 15μm, respectively.

[0056] A circularly polarized femtosecond Bessel laser is used to induce modification on the surface of the resonant structure layer wafer 200 along the desired processing trajectory, and the desired resonant structure is released by a wet etching process.

[0057] A magnetron sputtering process is used to deposit chromium and gold layers on the lower surface of the resonant structure layer wafer 200 and the upper surface of the bottom electrode layer wafer 300. To ensure the adhesion of the gold layer and avoid excessive loss in film quality factor, in this embodiment, the thickness of the sputtered chromium layer is 10 nm and the thickness of the gold layer is 50 nm.

[0058] A photoresist spraying process is used to spray negative photoresist onto the metal layers of the lower surface of the resonant structure layer wafer 200 and the upper surface of the bottom electrode layer wafer 300. After steps 3 and 4, microstructures exist on both the resonant structure layer wafer 200 and the bottom electrode layer wafer 300. At this point, the spin coating process used in step 4 is no longer sufficient to cover the protective resist, so a photoresist spraying process is used. To ensure the photolithographic accuracy of the metal electrodes, the spraying thickness of the negative photoresist is 1.5 μm. Then, the photoresist is patterned using a photolithography etching process, and after chromium-gold etching and photoresist cleaning processes, the first wafer metal electrode 204 on the lower surface of the resonant structure layer wafer 200 and the second wafer metal electrode 302 on the upper surface of the bottom electrode layer wafer 300 are fabricated.

[0059] A surface activation liquid layer matching the bonding anchor point size is printed on the lower surface of the cap layer wafer 100 and the upper surface of the bottom electrode layer wafer 300 using a screen printing process to assist bonding. Then, the cap layer wafer 100, the resonant structure layer wafer 200, and the bottom electrode layer wafer 300 are stacked sequentially from top to bottom and pre-bonded. The surface activation liquid is a 5% potassium hydroxide solution, and the pre-bonding is performed by standing at room temperature for 24 hours.

[0060] The pre-bonded wafer is placed in a bonding device and bonded under high vacuum conditions (<1E-3Pa), where the bonding temperature is 400°C and the bonding pressure is 2000N.

[0061] Wafers are cleaved to form individual sensor devices.

[0062] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A vacuum gauge suitable for high vacuum measurement, characterized in that: The structure includes a capping layer (1), a resonant structure layer (2), and a bottom electrode layer (3) arranged sequentially from top to bottom. A gas film gap structure with a height of 0.2~4 μm is provided between the capping layer (1) and the resonant structure layer (2). A capacitor gap structure with a height of 1~15 μm is provided between the resonant structure layer (2) and the bottom electrode layer (3). A first pit (11) is provided on the lower surface of the capping layer (1). 2) After bonding, the first pit (11) forms the gas film gap structure. The lower surface of the resonant structure layer (2) is provided with a first metal film layer (21), the upper surface of the bottom electrode layer (3) is provided with a second pit (31), and the surface of the second pit (31) is provided with a second metal film layer (32). After the resonant structure layer (2) and the bottom electrode layer (3) are bonded, the first metal film layer (21) and the second metal film layer (32) form a capacitor for driving and signal detection of the resonant structure layer (2).

2. The vacuum gauge suitable for high vacuum measurement according to claim 1, characterized in that: The second pit (31) has a gas channel on at least one side, through which external gas molecules enter the interior and interact with the resonant structure layer (2).

3. The vacuum gauge suitable for high vacuum measurement according to claim 1, characterized in that: The resonant structure layer (2) includes a bonding anchor point (22), a resonant beam (23), and a mass block (24). The first metal film layer (21) is uniformly distributed on the resonant beam (23) and the mass block (24) and the signal is extracted through the electrode on the bonding anchor point (22).

4. The vacuum gauge suitable for high vacuum measurement according to claim 3, characterized in that: The resonant structure layer (2) is a single bonded anchor point (22), a single resonant beam (23) and a single mass block (24) structure; or a double bonded anchor point (22), a three resonant beam (23) and a double mass block (24) structure; or a double bonded anchor point (22), a double resonant beam (23) and a single mass block (24) structure; the resonant structure layer (2) operates in the torsional oscillation mode of the resonant beam (23).

5. A vacuum gauge suitable for high vacuum measurement according to any one of claims 1 to 4, characterized in that: The cap layer (1), the resonant structure layer (2), and the bottom electrode layer (3) are all made of fused silica material.

6. The vacuum gauge suitable for high vacuum measurement according to claim 5, characterized in that: The thickness of the cap layer (1) is 0.2~2mm, the thickness of the resonant structure layer (2) is 0.03~0.5mm, and the thickness of the bottom electrode layer (3) is 1~5mm.

7. The vacuum gauge suitable for high vacuum measurement according to claim 5, characterized in that: The cap layer (1) and the resonant structure layer (2), as well as the resonant structure layer (2) and the bottom electrode layer (3), are bonded together by a hydrogen-oxygen catalytic bonding process.

8. A method for preparing a vacuum gauge suitable for high vacuum measurement as described in any one of claims 1 to 7, characterized in that: Includes the following steps: Step 1: Cleaning raw materials; Step 2: Wafer cleavage induction; Step 3: Preparation of the air film gap structure in the capping layer; Step 4: Fabrication of the resonant structure layer and metallization of the lower surface; Step 5: Fabrication of the capacitor gap structure in the bottom electrode layer and metallization of the upper surface; Step 6: Three-layer bonding; Step 7: Wafer dicing.

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