MEMS ionization vacuum sensor based on magnetic field assistance and manufacturing method thereof

Abstract

The invention discloses an MEMS ionization vacuum sensor based on magnetic field assistance and a manufacturing method thereof, and belongs to the technical field of microelectronics. The sensor comprises a glass substrate, an emitter electrode, a lead electrode, an electron emitter, a first insulating spacer layer, a grid electrode, a second insulating spacer layer, top glass, an ion deflection electrode, an ion collector, an annular electrode and a magnetic field generation part, the manufacturing method comprises the steps of preparation of the substrate and the top glass, bonding of the electron emitter, processing of the insulating spacer layer and the grid electrode, anodic bonding, laser bonding, installation of the magnetic field component and scribing. An electric field-magnetic field composite field is used for remarkably expanding the electron motion trail, the problems that an existing sensor is weak in ion flow and poor in anti-interference capacity are solved by combining the physical isolation design of an ionization and collection area, and the sensor has the advantages of being small in size, high in precision, good in consistency and low in cost and is suitable for the fields of semiconductor manufacturing and aerospace.

Description

Technical Field

[0001] This invention belongs to the field of microelectronics technology, specifically relating to a magnetic field-assisted MEMS ionization vacuum sensor and its manufacturing method. Background Technology

[0002] Vacuum sensors are devices used to measure gas pressure in a system. Among them, ionization vacuum sensors are precision instruments that detect vacuum by ionizing the gas molecules being measured and measuring the ion current. They are widely used in semiconductor manufacturing, vacuum coating, aerospace, scientific research and other fields, and are one of the core sensors for process monitoring and quality control in vacuum environments.

[0003] Currently, hot cathode ionization vacuum sensors have advantages such as high measurement accuracy and wide measurement range. The products are mature and widely used. Their core working principle is as follows: by heating the filament (usually tungsten or iridium alloy) to a high temperature to emit thermionic electrons, the electrons collide with gas molecules under the acceleration of the anode, causing them to ionize. The generated positive ions are captured by the ion collecting electrode, thus forming an ion current proportional to the gas pressure. Finally, the vacuum degree is inferred by measuring the ion current.

[0004] However, the classic structure of a thermionic vacuum sensor is a three-electrode system consisting of a cylindrical anode, a coaxial filament, and a ring-shaped ion collector. Its production primarily relies on traditional machining methods, which have several drawbacks. First, this three-electrode system design restricts the miniaturization of the sensor to some extent. Second, the precision machining requirements, complex assembly process, and heavy reliance on manual adjustment not only result in high manufacturing costs but also lead to insufficient batch-to-batch performance consistency. Given these issues, thermionic vacuum sensors have significant limitations in applications requiring miniaturization, low power consumption, long lifespan, and integration.

[0005] With the development of fields such as the Internet of Things (IoT), wearable devices, microsatellites, and rapid on-site detection, the market demand for miniaturized, low-power, and high-precision ionizing vacuum sensors is becoming increasingly urgent. The application of MicroElectromechanical Systems (MEMS) technology holds promise for meeting this demand. On the one hand, MEMS technology enables the miniaturization of sensor size; on the other hand, standardized processes help reduce production costs and facilitate mass production. However, for miniaturized ionizing vacuum sensors, several problems remain to be solved: the significant reduction in electron motion paths leads to weak ion currents; nonlinear error sources (such as X-ray effects and secondary electron emission interference) affect accuracy; and the measurement range is relatively narrow. These problems have prevented the widespread application of miniaturized ionizing vacuum sensors, and most commercially available thermionic vacuum sensors are still manufactured using traditional processes. Therefore, there is an urgent need for structural design and system optimization of thermionic vacuum sensors to improve performance and meet the needs of more application scenarios. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of traditional hot cathode ionization vacuum sensors, such as difficulty in miniaturization, high cost, and poor consistency, as well as the technical deficiencies of existing MEMS ionization vacuum sensors, such as weak ion current and weak anti-interference ability. This invention provides a magnetic field-assisted MEMS ionization vacuum sensor and its manufacturing method. The device is miniaturized through MEMS technology, and an electric-magnetic field composite field is introduced to extend the electron motion trajectory. Combined with the physical isolation design of the ionization and collection regions, high-precision and high-stability vacuum measurement is achieved. At the same time, it has the capability for mass production and meets the application needs of fields such as the Internet of Things and aerospace.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A magnetic field-assisted MEMS ionization vacuum sensor includes: Glass substrate (1); Two electrode pairs are formed on the upper and lower sides of the glass substrate (1), respectively. The upper electrode pair is an emitter electrode (2), and the lower electrode pair is a lead electrode (3). The emitter electrode (2) and the lead electrode (3) are connected through a first glass through-hole (4) penetrating the glass substrate (1). An electron emitter (5) is connected to the emitter electrode (2) by wire bonding to generate free electrons; The first insulating spacer layer (6) is used to connect the glass substrate (1) and the gate (7), and a through hole is provided in the center of the layer to serve as the first chamber for electron movement; The gate (7) is made of highly doped silicon wafer, with a square through-hole array processed in the center to form a gate structure. A positive voltage is applied to provide energy to free electrons and it serves as an electron collecting electrode. The second insulating spacer layer (8) is used to connect the gate (7) and the top glass (9), and a through hole is provided in the center of the layer to serve as a second chamber for electron movement; The top glass (9) has a through hole in its center for communication with the outside world and to provide a channel for ion extraction; Three electrodes are formed on the upper and lower sides of the top glass (9), respectively. The upper side is an ion deflection electrode (10) and an ion collection electrode (11), and the lower side is an annular electrode (12). The ion collection electrode (11) and the annular electrode (12) are connected through a second glass through hole (13) penetrating the top glass (9). The magnetic field generating component is used to construct a magnetic field in the cavity where electrons move. Together with the electric field, it forms an electromagnetic composite field. Based on the vertical reciprocating motion of electrons, the horizontal circular motion is generated by the Lorentz force of the magnetic field. The radius of the circular motion is controlled by the magnetic field strength, forming a spiral motion trajectory, which is used to effectively increase the total length of the electron motion trajectory.

[0008] In a preferred embodiment of the present invention, the magnetic field generating component includes a fixing clamp (16) and a first permanent magnet (14) and a second permanent magnet (15) fixed at both ends of the fixing clamp (16), and the first permanent magnet (14) and the second permanent magnet (15) are respectively located on both sides of the glass substrate (1) and the top glass (9).

[0009] In a preferred embodiment of the present invention, the first permanent magnet (14) and the second permanent magnet (15) may be replaced with Helmholtz coils.

[0010] In a preferred embodiment of the present invention, the thickness of the glass substrate (1) is 0.5-3 mm, and the material is selected from one of alkali-free glass, borosilicate glass or quartz glass; the surface of the glass substrate (1) connected to the first insulating spacer layer (6) is polished; the emitter electrode (2) is completely placed inside the through hole of the first insulating spacer layer (6).

[0011] In a preferred embodiment of the present invention, the material of the electron emitter (5) is selected from one of tungsten wire, platinum wire, iridium alloy wire, metal oxide coated metal wire, carbon nanotube array, and zinc oxide nanowire; the length of the electron emitter (5) is not less than the gap distance between two emitter electrodes (2).

[0012] In a preferred embodiment of the present invention, the thickness of the first insulating spacer layer (6) is 0.5-5mm, and the material is selected from one of alkali-free glass, borosilicate glass or quartz glass; the first insulating spacer layer (6) is polished on both sides and then processed with a laser ablation process to form a through hole with a diameter of 0.5-3mm.

[0013] In a preferred embodiment of the present invention, the gate (7) has a thickness of 0.1-0.5 mm and is made of a highly doped single-crystal silicon wafer with a resistivity ≤0.01Ω·cm; the square through-hole array of the gate (7) is processed by laser ablation process, the side length of the through-hole is 50-1000μm, and the through-hole spacing is 100-500μm; the gate (7) is connected to the first insulating spacer layer (6) and the second insulating spacer layer (8) by anodic bonding.

[0014] In a preferred embodiment of the present invention, the thickness of the second insulating spacer layer (8) is 0.5-5mm, the material is the same as that of the first insulating spacer layer (6), and the diameter of the central through hole is 0.5-3mm; the second insulating spacer layer (8) is connected to the gate (7) by anodic bonding and to the top glass (9) by laser bonding.

[0015] In a preferred embodiment of the present invention, the thickness of the top glass (9) is 0.5-3 mm, and the material is selected from one of alkali-free glass, borosilicate glass or quartz glass, and the diameter of the central through hole is 0.3-1.5 mm; the three electrodes formed on the upper and lower sides of the top glass (9) are prepared by photolithography coating process, the annular electrode (12) surrounds the central hole of the top glass (9) and is placed inside the through hole of the second insulating spacer layer (8); the ion deflection electrode (10) is given a positive voltage of 50-200V, and the ion collecting electrode (11) is given a negative voltage of -50 to -200V.

[0016] This invention provides a method for manufacturing a magnetic field-assisted MEMS ionization vacuum sensor, comprising the following steps: S1: Prepare a glass substrate (1) and electrode pair, including processing a first glass through hole (4) and filling it with metal, and photolithographically depositing an emitter electrode (2) and a lead electrode (3). S2: Prepare the top glass (9) and three electrodes, including the processing center hole and the second glass through hole (13) and fill them with metal, and prepare the ion deflection electrode (10), ion collection electrode (11) and ring electrode (12) by photolithography and film deposition. S3: The electron emitter (5) is welded to the emitter electrode (2) by wire bonding. S4: The first insulating spacer layer (6), the second insulating spacer layer (8) and the gate (7) are prepared by laser ablation process to process holes or through-hole arrays; S5: The gate (7) is connected to the first insulating spacer (6) and the second insulating spacer (8) by anodizing bonding process. The bonding parameters are temperature 250-500℃, voltage 1000V, and time 25min. S6: The first insulating spacer layer (6) is connected to the glass substrate (1) and the second insulating spacer layer (8) is connected to the top glass (9) using laser bonding technology. S7: Install the magnetic field generating component, fix the first permanent magnet (14) and the second permanent magnet (15) through the clamp (16), and build a magnetic field in the cavity where electrons move, which together with the electric field to form an electromagnetic composite field; S8: The bonded wafers from S7 are diced to obtain individual devices, and their electrical performance and hermeticity are tested.

[0017] Compared with the prior art, the present invention has the following significant advantages: (1) This invention proposes a MEMS ionization vacuum sensor based on magnetic field assistance. Its core innovation lies in the miniaturization of the device through MEMS technology, while introducing the synergistic effect of electric field-magnetic field composite field, which significantly extends the length of electron motion trajectory in a limited space, and specifically suppresses nonlinear interference mechanisms such as X-ray effect and secondary electron emission, thereby achieving high-precision vacuum degree measurement.

[0018] (2) Compared with traditional commercial ionization vacuum sensors, the present invention has the following advantages: First, relying on MEMS technology, the device size can be reduced to the millimeter level, breaking through the size limitation of traditional structures; Second, the standardized MEMS manufacturing process can realize mass production with high consistency and batch uniformity, effectively reducing the impact of process discreteness on device performance, significantly improving production efficiency and optimizing costs; Third, the compact design based on MEMS greatly improves its integration with peripheral circuits, signal processing modules and other electrical components, which is conducive to realizing system-level miniaturized packaging.

[0019] (3) Compared with existing miniaturized ionization vacuum sensors, this invention achieves key breakthroughs in measurement accuracy and anti-interference capability: First, through the combined effect of electric and magnetic fields, the trajectory of electrons in the ionization region is extended into a spiral trajectory, significantly increasing the probability of collision ionization between electrons and gas molecules, and solving the problem of weak ion flow caused by excessively short electron paths; Second, a structural design is adopted that physically isolates the ionization region from the ion collection region. The ion collection electrode is set outside the ionization region, which avoids interference from secondary electrons generated by ion collisions with the ion collection electrode on the initial electron motion, and also reduces the interference of soft X-rays caused by electron bombardment of the grid on the measurement signal. The combined effect of the above structural design and field synergy mechanism effectively improves the accuracy and stability of vacuum measurement, providing a feasible solution for the application of miniaturized high-precision vacuum sensors. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments or prior art, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of a MEMS ionization vacuum sensor provided in an embodiment of the present invention.

[0022] Figure 2 This is a flowchart illustrating a fabrication process for a MEMS ionization vacuum sensor, as provided in an embodiment of the present invention.

[0023] Figure 3 This is a schematic diagram of another MEMS ionization vacuum sensor provided in an embodiment of the present invention.

[0024] Figure 4 A flowchart of another MEMS ionization vacuum sensor fabrication process provided for an embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the installation structure of the permanent magnet provided in an embodiment of the present invention.

[0026] Figure 6 This is a schematic diagram of a magnetic field-assisted MEMS ionization vacuum sensor provided in an embodiment of the present invention.

[0027] Figure 7 This is a flowchart illustrating the fabrication process of a magnetic field-assisted MEMS ionization vacuum sensor, as provided in an embodiment of the present invention.

[0028] Figure 8 A flowchart illustrating the usage process of the MEMS ionization vacuum sensor provided in this embodiment of the invention.

[0029] Figure 9 This is a simulation diagram of the electron trajectory of a MEMS ionization vacuum sensor based on a magnetic field-assisted method, provided as an embodiment of the present invention.

[0030] Figure 10 This is a simulation diagram of ion trajectory based on magnetic field-assisted MEMS ionization vacuum sensing, provided as an embodiment of the present invention. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "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 the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific way. Therefore, they should not be construed as limiting the present invention.

[0032] Figure 6 Combination Figures 1-5 This invention provides a magnetic field-assisted MEMS ionization vacuum sensor, comprising: The glass substrate 1 serves as the basic support structure for the sensor.

[0033] Two electrode pairs are formed on the upper and lower sides of the glass substrate 1, respectively. The upper electrode pair is the emitter electrode 2, and the lower electrode pair is the lead electrode 3. The emitter electrode 2 and the lead electrode 3 are connected through a first glass through-hole 4 penetrating the glass substrate 1. The lead electrode 3 is used to realize the electrical connection between the sensor and the external circuit.

[0034] The electron emitter 5 is connected to the emitter electrode 2 by wire bonding to generate free electrons.

[0035] The first insulating spacer layer 6 is made of insulating glass and is used to connect the glass substrate 1 and the gate 7. It has a through hole in the center as the first chamber for electron movement.

[0036] The gate 7 is made of highly doped silicon wafer, with a square through-hole array fabricated in its center to form a gate mesh structure. A positive voltage is applied to provide energy to free electrons, and it also serves as an electron collector. In this embodiment, a positive voltage is applied to the gate 7 to provide an accelerating electric field for the free electrons emitted by the electron emitter 5 and to capture electrons that have not penetrated the gate mesh.

[0037] The second insulating spacer layer 8 is used to connect the gate 7 and the top glass 9, and a through hole is opened in the center of it to serve as a second chamber for electron movement.

[0038] The top glass 9 has a through hole in the center to connect with the outside world and provide a channel for ion extraction.

[0039] Three electrodes are formed on the upper and lower sides of the top glass 9, respectively. The upper side is the ion deflection electrode 10 and the ion collection electrode 11, and the lower side is the annular electrode 12. The ion collection electrode 11 and the annular electrode 12 are connected through the second glass through hole 13 penetrating the top glass 9.

[0040] The magnetic field generating component is used to construct a magnetic field in the cavity where electrons move. Together with the electric field, it forms an electromagnetic composite field. Based on the vertical reciprocating motion of electrons, the horizontal circular motion is generated by the Lorentz force of the magnetic field. The radius of the circular motion is controlled by the magnetic field strength, forming a spiral motion trajectory, which is used to effectively increase the total length of the electron motion trajectory.

[0041] In some embodiments, the magnetic field generating component includes a fixing clamp 16 and a first permanent magnet 14 and a second permanent magnet 15 fixed at both ends of the fixing clamp 16, with the first permanent magnet 14 and the second permanent magnet 15 located on both sides of the glass substrate 1 and the top glass 9, respectively. In this embodiment, a silicone pad is used to buffer the fixing clamp and the sensor to avoid squeezing the sensor structure. The permanent magnet is made of neodymium iron boron or samarium cobalt permanent magnets, with a magnetic field strength of 0.2-1.2T and a magnetic field direction perpendicular to the axis of the electron motion chamber.

[0042] In another embodiment, the first permanent magnet 14 and the second permanent magnet 15 can be replaced with Helmholtz coils. The Helmholtz coils adjust the magnetic field strength by 0.1-1T via an external circuit, and the magnetic field direction is perpendicular to the vertical motion direction of the electrons to generate a Lorentz force.

[0043] The thickness of the glass substrate 1 is 0.5-3mm, and the material is selected from one of alkali-free glass, borosilicate glass or quartz glass; the surface of the glass substrate 1 connected to the first insulating spacer layer 6 is polished; the emitter electrode 2 is completely placed inside the through hole of the first insulating spacer layer 6 to avoid the electrode edge blocking the movement of electrons.

[0044] The two electrode pairs (emitter electrode 2 and lead electrode 3) formed on the upper and lower sides of the glass substrate 1 are both prepared by photolithography deposition process: first, photoresist is coated on the surface of the glass substrate 1, and electrode patterns are formed by exposure and development. Then, a metal conductor thin film is deposited by magnetron sputtering or electron beam evaporation process. Finally, excess photoresist and metal are removed by lift-off process to obtain the electrode structure. The material of the metal conductor thin film is selected from gold, silver, copper, aluminum or chromium-gold composite layer, and the film thickness is 0.5-2μm.

[0045] The electron emitter 5 is made of a material selected from the following: thermionic emission electron materials, field emission electron materials, or photoelectric emission electron materials. Specifically, the electron emitter 5 is made of a material selected from the following: tungsten wire, platinum wire, iridium alloy wire, metal oxide coated metal wire, carbon nanotube array, zinc oxide nanowire, silicon tip array, or molybdenum tip array. The length of the electron emitter 5 is not less than the gap distance between two emitter electrodes 2, ensuring that both ends of the electron emitter 5 can be reliably connected to the emitter electrodes 2. The diameter of the electron emitter 5 is 1-20 μm to reduce the space occupied by the electron movement chamber. In this embodiment, the electron emitter 5 is connected to the upper emitter electrode 2 by wire bonding and is placed inside the through hole of the subsequent first insulating spacer layer 6 for emitting free electrons under voltage drive.

[0046] The thickness of the first insulating spacer layer 6 is 0.5-5 mm, and the material is selected from alkali-free glass, borosilicate glass, or quartz glass. After double-sided polishing, the first insulating spacer layer 6 is processed with a central through-hole using laser ablation technology, and the hole diameter is 0.5-3 mm. The processing steps of the first insulating spacer layer 6 are as follows: first, the glass substrate is double-sided polished to ensure the flatness of the upper and lower surfaces, preferably Ra≤0.1μm; then, a central through-hole is processed using laser ablation technology, with a hole diameter of 0.5-3 mm and a laser ablation spot diameter of 20-50 μm to ensure the perpendicularity and smoothness of the hole edge; the first insulating spacer layer 6 is connected to the glass substrate 1 by laser bonding, and the shear strength of the bonding interface is ≥15 MPa.

[0047] The gate 7 has a thickness of 0.1-0.5 mm and is made of highly doped single-crystal silicon wafer with a resistivity ≤0.01Ω·cm. The square through-hole array of the gate 7 is processed by laser ablation, with a hole side length of 50-1000μm and a hole spacing of 100-500μm. The gate 7 is connected to the first insulating spacer layer 6 and the second insulating spacer layer 8 by anodic bonding. In this embodiment, the square through-hole array of the gate 7 is processed by laser ablation, with a hole side length of 50-1000μm and a hole spacing of 100-500μm. The duty cycle of the through-hole array is 30%-50% to balance electron transmittance and electric field uniformity. The gate 7 is connected to the first insulating spacer layer 6 and the second insulating spacer layer 8 by anodic bonding.

[0048] The second insulating spacer layer 8 has a thickness of 0.5-5mm and is made of the same material as the first insulating spacer layer 6. The diameter of the central through hole is 0.5-3mm. The second insulating spacer layer 8 is connected to the gate 7 by anodic bonding and to the top glass 9 by laser bonding.

[0049] The top glass 9 has a thickness of 0.5-3 mm and is made of one of alkali-free glass, borosilicate glass, or quartz glass. The diameter of the central through-hole is 0.3-1.5 mm. Three electrodes formed on the upper and lower sides of the top glass 9 are fabricated using a photolithography process. The annular electrode 12 surrounds the central hole of the top glass 9 and is placed inside the through-hole of the second insulating spacer layer 8. The ion deflection electrode 10 is subjected to a positive voltage of 50-200V, and the ion collecting electrode 11 is subjected to a negative voltage of -50 to -200V.

[0050] In this embodiment, the three electrodes (ion deflection electrode 10, ion collection electrode 11, and ring electrode 12) formed on the upper and lower sides of the top glass 9 are prepared by photolithography and the material is the same as that of the emitter electrode 2 (gold, silver, copper, etc.), with a thickness of 0.5-2μm. The inner diameter of the lower ring electrode 12 is the same as the diameter of the central hole of the top glass 9, and the outer diameter is 0.2-1mm larger than the diameter of the hole. The ring electrode 12 is completely placed inside the through hole of the second insulating spacer layer 8. A positive voltage (50-200V) is applied to the upper ion deflection electrode 10 to deflect the positive ions, and a negative voltage (-50 to -200V) is applied to the upper ion collection electrode 11 to capture the deflected positive ions.

[0051] This invention also provides a method for manufacturing a magnetic field-assisted MEMS ionization vacuum sensor, comprising the following steps: S1: Prepare glass substrate 1 and electrode pair, including processing first glass through hole 4 and filling it with metal, and photolithography to prepare emitter electrode 2 and lead electrode 3.

[0052] In this embodiment, a glass substrate (alkali-free glass, borosilicate glass, or quartz glass) with a thickness of 0.5-3 mm is selected. Two vertically penetrating first glass vias 4 are fabricated on the glass substrate using laser processing, chemical etching, or mechanical processing. The via diameter is 50-100 μm. A metal seed layer (50-100 nm thick) is deposited on the inner wall of the first glass via 4 using a sputtering process. Then, copper or gold is filled in using an electroplating process, with the filling thickness being consistent with the thickness of the glass substrate, thus achieving conductive connection of the first glass via 4. The glass substrate is polished on both sides to ensure that the flatness Ra of the upper and lower surfaces is ≤0.1 μm. Subsequently, an emitter electrode 2 is fabricated on the upper side of the glass substrate and a lead electrode 3 is fabricated on the lower side using a photolithography deposition process to obtain the glass substrate 1.

[0053] S2: Prepare the top glass 9 and three electrodes, including the processing center hole and the second glass through hole 13 and fill them with metal, and prepare the ion deflection electrode 10, the ion collection electrode 11 and the ring electrode 12 by photolithography and film deposition.

[0054] In this embodiment, a glass substrate with a thickness of 0.5-3 mm is selected. A through hole (0.3-1.5 mm in diameter) is processed in the center using a laser ablation process, and a second vertical through-hole 13 (50-100 μm in diameter) is processed on the glass substrate. The second glass through-hole 13 is filled with metal using the same process as described above to achieve conductive connection. The glass substrate is polished on both sides, and then an ion deflection electrode 10 and an ion collection electrode 11 are prepared on the upper side of the glass substrate and an annular electrode 12 is prepared on the lower side using a photolithography coating process to obtain the top glass 9.

[0055] S3: Electron emitter 5 is welded to emitter electrode 2 by wire bonding.

[0056] In this embodiment, an electron emitter 5 (such as a tungsten wire or carbon nanotube array) is selected, and its two ends are welded to the emitter electrode 2 on the upper side of the glass substrate 1 by wire bonding process, so as to ensure that the length of the electron emitter 5 is not less than the gap distance of the emitter electrode 2.

[0057] S4: The first insulating spacer layer 6, the second insulating spacer layer 8 and the gate 7 are prepared by laser ablation process to process holes or through-hole arrays.

[0058] In this embodiment, a glass substrate with a thickness of 0.5-5mm is selected. After double-sided polishing, a through hole (0.5-3mm in diameter) is processed in the center using a laser ablation process to obtain the first insulating spacer layer 6 and the second insulating spacer layer 8. A highly doped silicon wafer (resistivity ≤0.01Ω·cm) with a thickness of 0.1-0.5mm is selected, and a square through hole array (through hole side length 50-1000μm, spacing 100-500μm) is processed using a laser ablation process to obtain the gate 7.

[0059] S5: The gate 7 is connected to the first insulating spacer layer 6 and the second insulating spacer layer 8 using an anodic bonding process. The bonding parameters are: temperature 250-500℃, voltage 1000V, and time 25min.

[0060] In this embodiment, the first insulating spacer layer 6, the gate 7, and the second insulating spacer layer 8 are stacked sequentially with the glass side facing the silicon wafer side, and placed in an anode bonding device. The anode bonding parameters are set as follows: temperature 250-500℃, voltage 1000V, and time 25min. During the bonding process, sodium ions in the glass migrate to the negative electrode (glass side) and form a depletion layer at the silicon-glass interface. Oxygen ions in the depletion layer react with silicon atoms to generate Si-O covalent bonds, thereby achieving reliable bonding between the first insulating spacer layer 6 and the gate 7, and between the second insulating spacer layer 8 and the gate 7.

[0061] S6: The first insulating spacer layer 6 is connected to the glass substrate 1, and the second insulating spacer layer 8 is connected to the top glass 9 using laser bonding technology.

[0062] In this embodiment, a glass substrate 1 (with a bonded electron emitter 5) is stacked with a first insulating spacer layer 6, and the electron emitter 5 is placed in a through hole in the first insulating spacer layer 6. A pulsed laser is used to irradiate the contact surface between the two, causing the interface material to partially melt and then cool and solidify, thereby achieving laser bonding. A second insulating spacer layer 8 is stacked with a top glass layer 9, and a ring electrode 12 is placed in a through hole in the second insulating spacer layer 8. Laser bonding is performed using the same laser parameters as described above.

[0063] S7: Install the magnetic field generating component, and fix the first permanent magnet 14 and the second permanent magnet 15 with the clamp 16 to construct a magnetic field in the electron movement chamber, which, together with the electric field, forms an electromagnetic composite field. In this embodiment, the two permanent magnets are symmetrically fixed to both sides of the sensor with the fixing clamp 16, and a silicone pad is placed between the clamp and the sensor. The clamps are tightened with screws to ensure that the magnetic field direction of the permanent magnets is perpendicular to the axis of the electron movement chamber.

[0064] S8: The bonded wafer from S7 is diced to obtain individual devices, and electrical performance and hermeticity are tested. In this embodiment, dicing and testing are performed as follows: The bonded wafer is placed on a dicing machine, and a diamond dicing wheel is used for dicing at a speed of 10-50 mm / s to obtain individual sensor devices; the individual devices are then subjected to electrical performance testing (electrode conductivity, leakage current) and hermeticity testing to screen qualified products.

[0065] The structure and fabrication method of the MEMS ionization vacuum sensor are further illustrated below with specific accompanying figures: Example 1

[0066] like Figure 1 As shown, the MEMS ionization vacuum sensor includes a glass substrate 1, an emitter electrode 2, a lead electrode 3, a first glass via 4, an electron emitter 5, a first insulating spacer layer 6, a gate 7, a second insulating spacer layer 8, a top glass layer 9, an ion deflector 10, an ion collector 11, a ring electrode 12, and a second glass via 13. An electromagnetic recombination field is constructed by applying an external magnetic field.

[0067] like Figure 2 As shown, Example 1 provides a method for fabricating a MEMS ionization vacuum sensor, including the following steps: S1: Two vertically penetrating micro-holes are fabricated on the glass substrate 1 by means of laser processing, chemical etching or mechanical processing, and conductive material is filled into the holes. Electroplating is then performed on the surface of the conductive material to achieve electrical connection.

[0068] S2: The through-hole of the top glass 9 is prepared by laser ablation.

[0069] S3: A vertically penetrating micro-hole is created on the top glass using methods such as laser processing, chemical etching, or mechanical processing. The hole is then filled with conductive material, and electroplating is performed on the surface of the conductive material to achieve electrical connection.

[0070] S4: Photolithography coating, coatings are deposited on the upper and lower sides of the glass substrate and the top glass as electrodes.

[0071] S5: The electron emitter is soldered to the emitter electrode on the substrate using wire bonding.

[0072] S6: The gate 7, the first insulating spacer layer 6, and the second insulating spacer layer 8 are prepared by laser ablation.

[0073] S7: The gate is connected to the two insulating spacers by anodic bonding.

[0074] S8: The second insulating spacer layer and the top glass are connected by laser bonding.

[0075] S9: The first insulating spacer layer and the glass substrate are connected by laser bonding.

[0076] Step S4 includes: photolithographic deposition on the upper side of the substrate glass; photolithographic deposition on the lower side of the substrate glass; photolithographic deposition on the upper side of the top layer glass; and photolithographic deposition on the lower side of the top layer glass.

[0077] Step S6 includes: laser ablation of the first insulating spacer glass to form a through-hole; laser ablation of the second insulating spacer glass to form a through-hole; and laser ablation of the gate silicon wafer to form a through-hole array, which is a gate mesh structure.

[0078] Step S7 includes: connecting the first insulating spacer layer and the gate by anodic bonding; and connecting the second insulating spacer layer and the gate by anodic bonding.

[0079] Anodic bonding involves cleaning and stacking glass and silicon wafers, with the glass connected to the negative terminal of the power supply and the silicon wafer connected to the positive terminal. During bonding, by applying specific voltage parameters and controlling the process temperature, sodium ions in the glass migrate to the cathode, forming a depletion layer several micrometers thick at the interface with the adjacent silicon wafer. The oxygen ions enriched in the depletion layer react chemically with silicon atoms on the silicon wafer surface to form stable Si-O covalent bonds, ultimately achieving a reliable bond between the glass and silicon interface. The conditions for anodic bonding are 250-500℃, 1000V, for 25 minutes.

[0080] Steps S8 and S9 include: the laser beam irradiates the contact surface of the two materials, releasing energy to bring the temperature to the melting point, the molten materials fuse to form a weld, and after cooling, a strong bonding interface is formed. Example 2

[0081] like Figure 3As shown, the MEMS ionization vacuum sensor includes a glass substrate 1, an emitter electrode 2, a permanent magnet 3, a first glass via 4, an electron emitter 5, a first insulating spacer layer 6, a gate 7, a second insulating spacer layer 8, a top glass layer 9, an ion deflection electrode 10, an ion collection electrode 11, a ring electrode 12, and a second glass via 13.

[0082] like Figure 4 As shown in Example 2, a method for fabricating a MEMS ionization vacuum sensor is provided, including the following steps: S1: Two vertically penetrating micro-holes are fabricated on the glass substrate 1, and conductive material is filled into the holes to achieve electrical connection.

[0083] S2: The through-hole of the top glass 9 is prepared by laser ablation.

[0084] S3: Create a tiny, vertically penetrating hole in the top glass and fill the hole with conductive material to achieve electrical connection.

[0085] S4: Photolithography coating, coatings are deposited on the upper and lower sides of the glass substrate and the top glass as electrodes.

[0086] S5: The electron emitter is soldered to the emitter electrode on the substrate using wire bonding.

[0087] S6: The gate 7, the first insulating spacer layer 6, and the second insulating spacer layer 8 are prepared by laser ablation.

[0088] S7: The gate is connected to the two insulating spacers by anodic bonding.

[0089] S8: The second insulating spacer layer and the top glass are connected by laser bonding.

[0090] S9: The first insulating spacer layer and the glass substrate are connected by laser bonding.

[0091] S10: Divide the bonded wafer to obtain individual devices.

[0092] S11: Fix the permanent magnet to the underside of the glass substrate.

[0093] In one implementation, steps S1, S2, S3, S4, S5, S6, S7, S8, and S9 are similar to those in Embodiment 1 above.

[0094] Step S11 includes: fixing the permanent magnet to the underside of the glass substrate by adhesive bonding. For example... Figure 5 As shown, the permanent magnet structure used has two through holes inside, which are used to bring out the electrodes and connect them to the circuit. Example 3

[0095] like Figure 6 As shown, a magnetic field-assisted MEMS ionization vacuum sensor includes a glass substrate 1, an emitter electrode 2, a lead electrode 3, a first glass through-hole 4, an electron emitter 5, a first insulating spacer layer 6, a gate 7, a second insulating spacer layer 8, a top glass layer 9, an ion deflection electrode 10, an ion collection electrode 11, a ring electrode 12, a second glass through-hole 13, a first permanent magnet 14, a second permanent magnet 15, and a fixing fixture 16.

[0096] like Figure 7 As shown, this invention provides a method for fabricating a MEMS ionization vacuum sensor, comprising the following steps: S1: Two vertically penetrating micro-holes are fabricated on the glass substrate 1, and conductive material is filled into the holes to achieve electrical connection.

[0097] S2: The through-hole of the top glass 9 is prepared by laser ablation.

[0098] S3: Create a tiny, vertically penetrating hole in the top glass and fill the hole with conductive material to achieve electrical connection.

[0099] S4: Photolithography coating, coatings are deposited on the upper and lower sides of the glass substrate and the top glass as electrodes.

[0100] S5: The electron emitter is soldered to the emitter electrode on the substrate using wire bonding.

[0101] S6: The gate 7, the first insulating spacer layer 6, and the second insulating spacer layer 8 are prepared by laser ablation.

[0102] S7: The gate is connected to the two insulating spacers by anodic bonding.

[0103] S8: The second insulating spacer layer and the top glass are connected by laser bonding.

[0104] S9: The first insulating spacer layer and the glass substrate are connected by laser bonding.

[0105] S10: Divide the bonded wafer to obtain individual devices.

[0106] S11: The clamp secures the ionization vacuum sensor and two permanent magnets.

[0107] Steps S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10 are similar to those in Examples 1 and 2 above.

[0108] like Figure 8As shown, the specific usage process of this MEMS ionization vacuum sensor is as follows: Circuit connection: Connect the sensor to the supporting circuit. Power supply configuration: Turn on the DC power supply and adjust the power supply voltage to the set value required for sensor operation to provide a stable energy input for the working process. Electron emission and ionization process: The electron emitter emits free electrons under the drive of the set voltage. The electrons move in the chamber and collide with neutral gas molecules to ionize and generate positive ions. Signal conversion and measurement: As the ionization process continues, the system enters dynamic equilibrium. At this time, the ion collecting electrode captures positive ions to form a stable weak ion current. After the ion current is processed by the transimpedance amplification and other signal conditioning circuits, a measurable current signal is output. Based on the pre-calibrated characteristic curve, the gas pressure value of the target space is calculated by back-calculation.

[0109] The working principle of a magnetic field-assisted MEMS ionization vacuum sensor is as follows: When a voltage is applied to the lead-out electrodes on the substrate, the electron emitter emits initial free electrons. These electrons are accelerated by the gate electric field within the cavity of the first insulating spacer layer. After gaining kinetic energy, some pass through the gate vias into the cavity of the second insulating spacer layer, while the remaining electrons are captured by the gate. Electrons entering the cavity of the second insulating spacer layer decelerate to zero velocity in the electric field created by the high voltage of the gate and the low voltage of the ring electrode (located below the top glass layer), then accelerate in the opposite direction towards the gate. Upon reaching the gate, some electrons are absorbed, while the rest pass through the vias back into the cavity of the first insulating spacer layer. This process repeats continuously, creating a continuous reciprocating trajectory in the vertical direction, significantly extending the effective path length.

[0110] During the reciprocating motion of free electrons, they collide with neutral molecules / atoms. When the electron energy exceeds the ionization energy of gas molecules, it can ionize the latter, generating an avalanche of electrons and producing positive ions. These positive ions migrate directionally under the influence of an electric field, pass through the top layer aperture, and are captured by the collecting electrode under the combined action of the two electrodes on the upper side of the top layer, forming an ion current proportional to the gas pressure. Finally, the vacuum level can be inferred by measuring the ion current.

[0111] When a magnetic field is introduced to construct an electromagnetic composite field, electrons, based on their vertical reciprocating motion, are controlled by the Lorentz force of the magnetic field to produce horizontal circular motion (the radius of the circular motion is controlled by the magnetic field strength), forming a spiral trajectory. This effectively increases the total length of the electron trajectory. This composite field effect significantly increases the probability of collision and ionization between electrons and gas molecules, which can effectively alleviate the problem of weak ion flow caused by the short electron path.

[0112] Meanwhile, the structural design employs an external ion collector, spatially isolating the ionization region from the ion collection region. On one hand, this structure suppresses the interference of secondary electron emission generated by ion collisions with the ion collector on the initial electron motion; on the other hand, it reduces the influence of soft X-rays induced by electron bombardment of the ion collector on the measurement signal, thereby significantly improving the accuracy and stability of vacuum degree measurement.

[0113] The simulation results of the structure prepared by this invention are shown below: Electron trajectory such as Figure 9 As shown, after electron emission, under the combined effect of the electromagnetic composite field, it exhibits a superimposed trajectory of vertical reciprocating motion and horizontal circular motion. During the motion, the electron continuously collides and ionizes with neutral molecules / atoms in the chamber, generating positive ions. Simulation results show that in a chamber with a height of 1.80 mm, the average trajectory length of the electron can reach 4.24 mm, significantly extending the motion path and effectively improving the probability of collisional ionization.

[0114] The trajectory of the positive ions produced by ionization is as follows Figure 10 As shown, when the electron energy exceeds the ionization energy of the gas molecules, the collision will cause the molecules to ionize and release positive ions. Under the action of the electric field, most of the positive ions migrate along a specific path, are drawn out through the through-holes in the top glass, and converge to the surface of the ion collecting electrode under the action of the deflection electrode of the top glass, ultimately forming an ion current signal proportional to the gas pressure.

[0115] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A magnetic field assisted based MEMS ionization vacuum sensor characterized in that, include: Glass substrate (1); Two electrode pairs are formed on the upper and lower sides of the glass substrate (1), respectively. The upper electrode pair is an emitter electrode (2), and the lower electrode pair is a lead electrode (3). The emitter electrode (2) and the lead electrode (3) are connected through a first glass through-hole (4) penetrating the glass substrate (1). An electron emitter (5) is connected to the emitter electrode (2) by wire bonding to generate free electrons; The first insulating spacer layer (6) is used to connect the glass substrate (1) and the gate (7), and a through hole is provided in the center of the layer to serve as the first chamber for electron movement; The gate (7) is made of highly doped silicon wafer, with a square through-hole array processed in the center to form a gate structure. A positive voltage is applied to provide energy to free electrons and it serves as an electron collecting electrode. The second insulating spacer layer (8) is used to connect the gate (7) and the top glass (9), and a through hole is provided in the center of the layer to serve as a second chamber for electron movement; The top glass (9) has a through hole in its center for communication with the outside world and to provide a channel for ion extraction; Three electrodes are formed on the upper and lower sides of the top glass (9), respectively. The upper side is an ion deflection electrode (10) and an ion collection electrode (11), and the lower side is an annular electrode (12). The ion collection electrode (11) and the annular electrode (12) are connected through a second glass through hole (13) penetrating the top glass (9). The magnetic field generating component is used to construct a magnetic field in the cavity where electrons move. Together with the electric field, it forms an electromagnetic composite field. Based on the vertical reciprocating motion of electrons, the horizontal circular motion is generated by the Lorentz force of the magnetic field. The radius of the circular motion is controlled by the magnetic field strength, forming a spiral motion trajectory, which is used to effectively increase the total length of the electron motion trajectory.

2. The magnetic field-assisted MEMS ionization vacuum sensor of claim 1, wherein, The magnetic field generating component includes a fixing clamp (16) and a first permanent magnet (14) and a second permanent magnet (15) fixed at both ends of the fixing clamp (16), and the first permanent magnet (14) and the second permanent magnet (15) are located on both sides of the glass substrate (1) and the top glass (9), respectively.

3. The magnetic field-assisted MEMS ionization vacuum sensor according to claim 2, characterized in that, The first permanent magnet (14) and the second permanent magnet (15) can be replaced with Helmholtz coils.

4. The magnetic field-assisted MEMS ionization vacuum sensor according to claim 1, characterized in that, The thickness of the glass substrate (1) is 0.5-3mm, and the material is selected from one of alkali-free glass, borosilicate glass or quartz glass; the surface of the glass substrate (1) connected to the first insulating spacer layer (6) is polished; the emitter electrode (2) is completely placed inside the through hole of the first insulating spacer layer (6).

5. The magnetic field-assisted MEMS ionization vacuum sensor according to claim 1, characterized in that, The material of the electron emitter (5) is selected from one of tungsten wire, platinum wire, iridium alloy wire, metal oxide coated metal wire, carbon nanotube array, and zinc oxide nanowire; the length of the electron emitter (5) is not less than the gap distance between two emitter electrodes (2).

6. The magnetic field-assisted MEMS ionization vacuum sensor according to claim 1, characterized in that, The thickness of the first insulating spacer layer (6) is 0.5-5mm, and the material is selected from one of alkali-free glass, borosilicate glass or quartz glass; the first insulating spacer layer (6) is polished on both sides and then processed with laser ablation process to form a through hole with a diameter of 0.5-3mm.

7. The magnetic field-assisted MEMS ionization vacuum sensor according to claim 1, characterized in that, The gate (7) has a thickness of 0.1-0.5 mm and is made of a highly doped single-crystal silicon wafer with a resistivity of ≤0.01Ω·cm. The square through-hole array of the gate (7) is processed by laser ablation, with a through-hole side length of 50-1000μm and a through-hole spacing of 100-500μm. The gate (7) is connected to the first insulating spacer layer (6) and the second insulating spacer layer (8) by anodic bonding.

8. The magnetic field-assisted MEMS ionization vacuum sensor according to claim 1, characterized in that, The second insulating spacer layer (8) has a thickness of 0.5-5 mm and is made of the same material as the first insulating spacer layer (6). The diameter of the central through hole is 0.5-3 mm. The second insulating spacer layer (8) is connected to the gate (7) by anodic bonding and to the top glass (9) by laser bonding.

9. The magnetic field-assisted MEMS ionization vacuum sensor according to claim 1, characterized in that, The thickness of the top glass (9) is 0.5-3mm, and the material is selected from one of alkali-free glass, borosilicate glass or quartz glass. The diameter of the central through hole is 0.3-1.5mm. The three electrodes formed on the upper and lower sides of the top glass (9) are prepared by photolithography. The ring electrode (12) surrounds the central hole of the top glass (9) and is placed inside the through hole of the second insulating spacer layer (8). The ion deflection electrode (10) is given a positive voltage of 50-200V, and the ion collection electrode (11) is given a negative voltage of -50 to -200V.

10. A method for manufacturing a MEMS ionization vacuum sensor based on magnetic field assistance, characterized in that, Includes the following steps: S1: Prepare a glass substrate (1) and electrode pair, including processing a first glass through hole (4) and filling it with metal, and photolithographically depositing an emitter electrode (2) and a lead electrode (3). S2: Prepare the top glass (9) and three electrodes, including the processing center hole and the second glass through hole (13) and fill them with metal, and prepare the ion deflection electrode (10), ion collection electrode (11) and ring electrode (12) by photolithography and film deposition. S3: The electron emitter (5) is welded to the emitter electrode (2) by wire bonding. S4: The first insulating spacer layer (6), the second insulating spacer layer (8) and the gate (7) are prepared by laser ablation process to process holes or through-hole arrays; S5: The gate (7) is connected to the first insulating spacer (6) and the second insulating spacer (8) by anodizing bonding process. The bonding parameters are temperature 250-500℃, voltage 1000V, and time 25min. S6: The first insulating spacer layer (6) is connected to the glass substrate (1) and the second insulating spacer layer (8) is connected to the top glass (9) using laser bonding technology. S7: Install the magnetic field generating component, fix the first permanent magnet (14) and the second permanent magnet (15) through the clamp (16), and build a magnetic field in the cavity where electrons move, which together with the electric field to form an electromagnetic composite field; S8: The bonded wafers from S7 are diced to obtain individual devices, and their electrical performance and hermeticity are tested.

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