Vacuum isolation device and scanning electron microscope

Abstract

This invention belongs to the field of precision devices and relates to vacuum isolation devices and scanning electron microscopes. The vacuum isolation device includes a main component with a cavity, the bottom of which includes a sealing surface with a hole. A main valve body, an auxiliary valve body, a side-pressing component, and an elastic component are installed inside the cavity. The auxiliary valve body and the side-pressing component cooperate to press and fix the main valve body from opposite sides, applying downward pressure to the main valve body and pressing the sealing ring of the main valve body against the sealing surface, thus achieving vacuum isolation of the cavity. It also includes an elastic component, with one end fixed to the auxiliary valve body and the second end extending into the main valve body. A pressure block is installed inside the main valve body, and the second end of the elastic component is pressed by the pressure block and deforms downwards. When the elastic component moves relative to the main valve body with the auxiliary valve body, releasing the deformation stress, it pushes the main valve body upwards. This invention is applied in ultra-clean environments to avoid particulate matter contamination of the sealed cavity environment caused by friction during valve body movement.

Description

Technical Field

[0001] This invention belongs to the field of precision device technology, and specifically relates to vacuum isolation valves and scanning electron microscopes. Background Technology

[0002] As scanning electron microscopes (SEMs) become more powerful and their resolution requirements increase, the vacuum requirements for the electron gun tip also become higher. For example, a vacuum level better than 1E-8Pa is required. Therefore, an ultra-high vacuum isolation valve is needed to form a strict seal for the vacuum chamber of the electron gun. This isolation valve seals the electron channel, thus forming a high-vacuum sealed chamber.

[0003] The working vacuum of the electron gun's ultra-high vacuum chamber is achieved by the coordinated operation of molecular pumps and ion pumps. Due to the special nature of the ion pump's operation, it is always on. Therefore, during electron tube testing, experiments, and operation, other modules (parts other than the electron gun in the SEM electron tube) inevitably need to be paused. However, the ultra-high vacuum of the electron gun must not be broken. At this time, an ultra-high vacuum isolation valve is needed to isolate the ultra-high vacuum chamber of the electron gun section.

[0004] In existing ultra-high vacuum isolation devices, the sealing block is moved by a vacuum inlet and works with a stop to seal the electron beam channel. However, the relative sliding between the sealing block and the sealing surface, as well as between the sealing block and the stop, results in high friction and generates excessive particulate matter, which contaminates the entire electron optical tube, shortens the lifespan of the electron gun, and increases the roughness of the sealing surface, affecting the ultra-high vacuum level inside the electron gun cavity. Summary of the Invention

[0005] To address the existing technical problems, this invention provides a vacuum isolation device that can be used for ultra-high vacuum isolation of the electron gun section of an SEM electron microscope tube. It minimizes contamination of the electron optical tube, effectively protects the electron gun, and maintains the ultra-high vacuum level within the cavity.

[0006] The vacuum isolation device provided by the present invention includes a main component with a cavity, the bottom of which includes a sealing surface with a hole; a main valve body, an auxiliary valve body, a side extrusion member, and an elastic member are installed in the cavity; the auxiliary valve body and the side extrusion member cooperate with each other to press and fix the main valve body from opposite sides and apply downward pressure to the main valve body, thereby pressing the main valve body tightly against the sealing surface and realizing vacuum isolation of the cavity;

[0007] It also includes an elastic element, the first end of which is fixed to the auxiliary valve body and the second end of which extends into the main valve body; a pressure block is installed in the main valve body, and the second end of the elastic element is pressed by the pressure block and deforms downward; when the elastic element moves relative to the main valve body with the auxiliary valve body and releases the deformation stress, it pushes the main valve body upward.

[0008] Preferably, the second end of the elastic element has a waist-shaped hole, the length direction of the waist-shaped hole is parallel to the moving direction of the main valve body, and the pressure block is connected to the main valve body by a connector passing through the waist-shaped hole;

[0009] When the auxiliary valve body retracts and resets, the waist-shaped hole of the elastic element causes the auxiliary valve body to loosen from the main valve body. The elastic element then quickly releases stress at the bottom of the pressure block and pushes the pressure block upward, thereby causing the main valve body to disengage from the sealing surface.

[0010] Preferably, the bottom of the pressure block near the auxiliary valve body is formed with an arc-shaped transition surface, and the elastic element is in close contact with the transition surface when it deforms;

[0011] The auxiliary valve body includes a mounting groove for positioning an elastic element, the bottom surface of which is formed with a slope for avoiding deformation of the elastic element, the outer side of which slopes downward.

[0012] Preferably, the auxiliary valve body is driven to connect to the main valve body; the main valve body includes a first pressure-bearing inclined surface, and the auxiliary valve body includes a compression inclined surface adapted to the first pressure-bearing inclined surface; when the cavity is in a vacuum isolation state, the compression inclined surface presses down to press the first pressure-bearing inclined surface.

[0013] Preferably, the side extrusion member is fixedly installed in the cavity; the main valve body further includes a second pressure-bearing inclined surface;

[0014] The main valve body is configured such that it is driven by the auxiliary valve body to move toward the hole until its second pressure-bearing inclined surface is abutted by the side extrusion member and its first pressure-bearing inclined surface is abutted by the auxiliary valve body, at which point the main valve body presses down to seal the cover and seals the hole.

[0015] The bottom of the main valve body is provided with a sealing ring for sealing the hole, and a dust collection groove is provided on the sealing surface of the cavity between the hole and the sealing ring.

[0016] Preferably, the main valve body further includes a valve seat with a valve plate at the bottom, and the sealing ring is installed at the bottom of the valve plate;

[0017] A fastening fitting is formed inside the valve seat above the valve plate, and the connecting member is fixedly connected to the fastening fitting and the pressure block.

[0018] Optionally, the connecting member is a screw, and the fastening fitting is a stud with internal threads. The screw is screwed onto the stud to lock the pressure block.

[0019] Alternatively, the connector is a snap-fit, and the fastening fitting is a slotted seat, with the connector snapping onto the seat to lock the pressure block.

[0020] Furthermore, the auxiliary valve body is connected to a vacuum inlet for driving the movement of the auxiliary valve body, and a top extrusion member is installed above the auxiliary valve body in the cavity, the top extrusion member pressing the auxiliary valve body downward;

[0021] Both the top extruder and the side extruder include rollers that rotate about an axis, which is fixed to the main component;

[0022] When the auxiliary valve body moves, there is rolling friction between the top extrusion member and the top surface of the auxiliary valve body; when the main valve body and the side extrusion member move in relation to each other, there is rolling friction between the roller and the second pressure inclined surface.

[0023] Another object of the present invention is to provide a scanning electron microscope comprising an electron gun and a vacuum system for providing a vacuum environment for the electron gun; the vacuum system includes the aforementioned vacuum isolation device, wherein the electron gun is disposed above the cavity of the vacuum isolation device, and other modules are disposed below the cavity. The vacuum isolation device is used to intermittently seal the electron beam channel to form a vacuum-sealed cavity for the electron gun.

[0024] Preferably, an aperture is installed at the bottom of the cavity at the corresponding position of the hole to separate the vacuum sealing cavity of the electron gun from other modules by pressure difference.

[0025] The beneficial effects of this invention are as follows:

[0026] When the vacuum isolation device of the present invention is in operation, the auxiliary valve body and the side extrusion member cooperate with each other to extrude the main valve body from opposite sides and apply downward pressure to the main valve body, pressing the sealing ring of the main valve body tightly against the sealing surface of the cavity, thereby achieving effective vacuum isolation between the upper and lower parts of the cavity. The auxiliary valve body of the present invention only requires single-degree-of-freedom movement, the operation process is simple, and it cooperates with the inclined structure of the side extrusion member and the main valve body to easily achieve self-locking; moreover, it is reliable in operation, and the components adopt a pure mechanical seal, so as long as the movement stroke is in place, a reliable seal can be achieved.

[0027] This application installs an elastic element on the auxiliary valve body. The second end of the elastic element floats and extends into the main valve body. After being pressed by the pressure block of the main valve body, it bends downward and deforms, thereby storing energy. The second end of the elastic element also has a waist-shaped hole. On the one hand, when contacting the seal, the auxiliary valve body moves a small distance to the right, and the waist-shaped hole creates a horizontal degree of freedom between it and the main valve body, thereby releasing the pressure on the main valve body. In turn, the pressure block releases the second end of the elastic element to a certain extent. At the same time, the elastic element quickly rebounds upward to release energy, lifting the pressure block and the main valve body, so that the main valve body no longer contacts the sealing surface. This prevents friction with the sealing surface during movement, thus avoiding the generation of particulate matter such as dust, maintaining the cleanliness of the electron gun vacuum chamber, protecting the performance of the gun tip and ion pump, and extending its service life. On the other hand, after the main valve body rebounds to its position, the waist-shaped hole of the elastic element continues to drive the pressure block and the main valve body to move horizontally together, thus achieving a mechanical transmission effect.

[0028] This application effectively improves working efficiency through a vacuum isolation device, eliminating the need to repeatedly turn on the vacuum pump to maintain the vacuum level in the electron gun section; the vacuum isolation device isolates the ultra-high vacuum chamber of the electron gun, protecting the ion pump, making greater use of the ion pump, and extending the performance and lifespan of the ion pump.

[0029] Furthermore, as can be seen from the above disclosure, this application has a small number of parts, a simple structure, quick assembly, and low manufacturing cost, which is conducive to its widespread application. Attached Figure Description

[0030] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0031] Figure 1 This is a three-dimensional structural diagram of the vacuum isolation device of the present invention;

[0032] Figure 2 This is a top view of the vacuum isolation device of the present invention;

[0033] Figure 3 yes Figure 2 Cross-sectional view of section AA;

[0034] Figure 4 This is a partial structural diagram of a vacuum isolation device. The pressure block is hidden in the diagram, and the elastic element is in a free state.

[0035] Figure 5 This is a structural diagram of the main valve body of the vacuum isolation device;

[0036] Figure 6 This is a diagram of the pressure block structure of the vacuum isolation device;

[0037] Figure 7This is a schematic diagram of the operation of the main valve body when the vacuum isolation is released according to the present invention.

[0038] The diagram is marked as follows:

[0039] 1. Main component; 11. Cavity; 12. Sealing surface; 13. Hole; 14. Strip groove; 15. Dust collection trough;

[0040] 2. Main valve body; 21. First pressure-bearing inclined surface; 22. Second pressure-bearing inclined surface; 23. Valve seat; 231. Valve plate; 232. Sealing ring; 234. Fastening parts; 24. Pressure block; 241. Transition surface; 242. Connecting parts;

[0041] 3. Auxiliary valve body; 31. Extrusion bevel; 32. Screw; 33. Mounting groove; 331. Slope;

[0042] 4. Elastic element; 41. First end; 42. Second end; 43. Waist-shaped hole;

[0043] 5. Side extrusion component; 51. Shaft; 52. Roller; 53. Set screw;

[0044] 6. Top extrusion component;

[0045] 7. Aperture. Detailed Implementation

[0046] Reference will now be made in detail to various embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. In the following description of the drawings, the same reference numerals refer to the same components. Generally, only differences with respect to the various embodiments are described. Each example is provided by way of explanation and is not intended to limit the invention.

[0047] like Figures 1 to 5 As shown, this embodiment provides a vacuum isolation device for use in scenarios with high environmental cleanliness requirements, where the friction between the main valve body and the sealing surface during the pushing process should not generate a large amount of particulate matter. For example, this vacuum isolation device can be used in the sealing structure of the electron beam vacuum system of a scanning electron microscope, but it is not limited to this scenario.

[0048] The vacuum isolation device includes a main component 1 with a cavity 11. It is known that the vacuum cavity has a closed structure. Figure 1-3 The closed structure of the upper part of the cavity is omitted. The bottom of the cavity 11 of the main component 1 includes a horizontal and smooth sealing surface 12, which can be slightly raised to facilitate contact and sealing with the main valve body 2. A small hole 13 is opened in the sealing surface 12, through which the electron beam passes during scanning.

[0049] The main valve body 2, auxiliary valve body 3, side extrusion member 5, and elastic member 4 are installed within the cavity 11 of the main component. The main valve body 2 is used to seal the hole 13 of the main component 1, thereby achieving vacuum isolation above the cavity 11. Preferably, a sealing ring 232 for sealing the hole 13 is embedded in the bottom of the main valve body 2 to enhance the sealing effect; a dovetail groove can be opened at the bottom of the main valve body 2, and the sealing ring 232 is embedded in the dovetail groove to form a reliable connection and fit with the main valve body 2. However, this application does not limit the use of other installation structures for the sealing ring.

[0050] During operation, the auxiliary valve body 3 and the side extrusion member 5 cooperate to extrude the main valve body 2 from opposite sides, applying downward pressure to the main valve body 2 and pressing the sealing ring 232 of the main valve body 2 tightly onto the sealing surface 12 of the cavity, achieving vacuum isolation between the upper and lower parts of the cavity. This application does not limit the source of the downward pressure on the main valve body 2; it can come from the auxiliary valve body 3, the side extrusion member 5, or both simultaneously, or other components can be used to press against the main valve body 2. Preferably, the main valve body 2 is subjected to the downward pressure from both the auxiliary valve body 3 and the side extrusion member 5 to improve the balance and stability of the seal between the main valve body 2 and the sealing surface 12, and to allow the elastic member 4 to smoothly lift the main valve body 2. This process will be explained in detail below.

[0051] In a preferred embodiment, the side extrusion member 5 and the auxiliary valve body 3 are located on the left and right sides of the main valve body 2, respectively. The left and right sides of the main valve body 2 respectively include a second pressure-bearing inclined surface 22 and a first pressure-bearing inclined surface 21. The auxiliary valve body 3 is driven and connected to the main valve body 2, that is, the auxiliary valve body 3 can push the main valve body 2 to reciprocate in the horizontal direction. The auxiliary valve body 3 includes an extrusion inclined surface 31 adapted to the first pressure-bearing inclined surface 21. When the cavity is in a vacuum isolation state, the extrusion inclined surface 31 presses down on the first pressure-bearing inclined surface 21. That is, the main valve body 2 is driven by the auxiliary valve body 3 to move towards the hole 13 until its first pressure-bearing inclined surface 21 is abutted by the extrusion inclined surface 31 of the auxiliary valve body 3 and its second pressure-bearing inclined surface 22 is abutted by the side extrusion member 5. At this point, the main valve body 2 presses down on the sealing surface 12 to seal the hole 13 of the main component. More specifically, the first pressure-bearing inclined surface 21 and the second pressure-bearing inclined surface 22 receive horizontal thrust from the auxiliary valve body 3 and the side extrusion member 5, and the two thrusts are in opposite directions, thus keeping the main valve body 2 stationary on the sealing surface 12. The first pressure-bearing inclined surface 21 and the second pressure-bearing inclined surface 22 also receive downward pressure from the auxiliary valve body 3 and the side extrusion member 5, which presses the sealing ring 232 tightly against the sealing surface 12 to achieve a vacuum isolation effect.

[0052] In other embodiments, the second pressure-bearing inclined surface 22 of the main valve body can also be replaced with a vertical surface. In this case, the side extrusion member 5 only applies a rightward thrust to the main valve body 2, and its downward pressure on the vertical surface disappears. The main valve body 2 is pressed onto the sealing surface 12 only by the cooperation of the auxiliary valve body 3 and the first pressure-bearing inclined surface 21.

[0053] To ensure the movement accuracy of the main valve body 2 and the auxiliary valve body 3, a strip groove 14 with a width adapted to the main valve body 2 and the auxiliary valve body 3 can be machined in the cavity 11. The side extrusion member 5 is installed in the strip groove 14, and the main valve body 2 and the auxiliary valve body 3 both move along the strip groove 14.

[0054] This vacuum isolation device also includes an elastic element 4, which is mainly used for energy storage and facilitates lifting the main valve body. This application does not limit the type of elastic element 4. For example, it can be a flat spring, a corrugated spring, an injection-molded elastomer, or other components with a rebound effect. In one embodiment, a flat metal spring with better energy storage effect and longer service life is selected. The first end 41 of the elastic element 4 is fixed to the auxiliary valve body 3. In a preferred embodiment, its first end 41 is fixedly connected to the auxiliary valve body 3 by a screw 32. The screw can be made of titanium alloy TC4, but is not limited to this material.

[0055] The second end 42 of the elastic element 4 extends into the main valve body 2. A pressure block 24 is installed inside the main valve body 2. The second end 42 of the elastic element 4 is bent downward by the pressure block 24, so that the elastic element 4 stores energy. The second end 42 of the elastic element 4 has an oblong hole 43. The length direction of the oblong hole 43 is parallel to the movement direction of the main valve body 2. The pressure block 24 is connected to the main valve body 2 by a connector 242 that passes through the oblong hole 43.

[0056] like Figure 7 As shown, when the auxiliary valve body 3 retracts and resets, the elastic element 4 is pulled to the right by the auxiliary valve body 3. The waist-shaped hole 43 moves a small distance relative to the pressure block 24 and the connecting piece 242 (this distance is related to the length of the waist-shaped hole 43), causing the auxiliary valve body 3 to release the main valve body 2, and a small distance is generated between the two. During this process, the main valve body 2 remains basically stationary in the horizontal direction. The elastic element 4, which has stored energy, quickly releases stress at the bottom of the pressure block 24, thereby rebounding upward and lifting the pressure block 24, thereby causing the main valve body 2 to separate from the sealing surface 12. Then, the main valve body 2 continues to follow the auxiliary valve body 3 and move away from the hole 13, thus breaking the vacuum. Therefore, during the entire process of breaking the vacuum of the main valve body 2, the main valve body 2 never contacts the sealing surface 12, that is, no particulate matter is generated due to friction with the sealing surface 12, which improves the cleanliness of the environment.

[0057] like Figure 6As shown, in a preferred embodiment, the bottom of the pressure block 24 is near the auxiliary valve body 3, that is, the right side is formed with an arc-shaped transition surface 241. When the pressure block 24 squeezes the elastic member 4 to make it bend and deform downward, the deformed part of the elastic member 4 is close to the arc-shaped transition surface 241. The transition surface 241 prevents the elastic member 4 from being over-bent due to excessive load and making it difficult to rebound.

[0058] like Figure 4 As shown, the auxiliary valve body 3 includes a mounting groove 33 for positioning the elastic element 4, and the first end 41 of the elastic element 4 is fixed within the mounting groove 33. Similarly, as Figure 3 and Figure 7 As shown, the bottom surface of the mounting groove 33 is formed with a slope 331 for avoiding the deformation of the elastic member 4. The outer side of the slope 331 is inclined downward. When the elastic member 4 is deformed by the pressure block 24, it enters above the slope 331, so there will be no interference with the mounting groove 33.

[0059] The specific installation structure of the pressure block 24 and the main valve body 2 is described below.

[0060] Please refer to Figures 3 to 5 The main valve body 2 includes a valve seat 23 with a valve plate 231 at the bottom. A sealing ring 232 is embedded in the valve plate 231, and the bottom of the sealing ring 232 protrudes from the valve plate 231 to press the sealing surface 12. A cavity is provided in the valve seat 23 above the valve plate 231. A fastening fitting 234 is formed in the cavity. A connecting member 242 is fixedly connected to the fastening fitting 234 and the pressure block 24. An elastic member 4 extends into the cavity below the pressure block 24, and the width of the waist-shaped hole 43 of the elastic member 4 is sufficient to allow it to avoid interference with the connecting member 242 and the fastening fitting 234 when the waist-shaped hole moves.

[0061] Please refer to Figure 5 Specifically, the connector 242 can be a screw, and the fastening fitting 234 can be a stud with internal threads. The tail of the screw is screwed into the stud, and the head presses against the pressure block 24, thereby locking the pressure block 24. The screw is made of beryllium copper, which is non-magnetic and has a low outgassing rate, making it suitable for ultra-high vacuum environments. Alternatively, the connector 242 can be a snap-fit ​​(not shown in the figure), and the fastening fitting 234 can be a retainer with a slot. The bottom of the snap-fit ​​engages in the slot, and its top presses against the pressure block 24, thereby locking the pressure block 24. This is a snap-fit ​​method well known in the art, and therefore will not be described in detail. This application does not limit other conventional connection methods of the connector 242.

[0062] The side extrusion member 5 is fixedly installed in the cavity. In one specific implementation, the side extrusion member 5 includes a roller 52 that rotates around a shaft 51, with both ends of the shaft 51 fixed in the cavity. The shaft 51 is fixed by means including but not limited to being fixed by a set screw 53, which is threadedly connected to the main component 1. To increase reliability, double set screws 53 can be used for stacked tightening to prevent the structure of the shaft 51 from loosening and affecting the connection reliability.

[0063] The preferred side extrusion component 5 adopts a roller 52 structure; please refer to this carefully. Figure 7 When the auxiliary valve body 3 detaches from the first pressure-bearing inclined surface 21 of the main valve body 2, the main valve body 2 is released. The pressure block 24 of the main valve body 2 is lifted by the rebound force of the elastic element 4. At this time, the second pressure-bearing inclined surface 22 of the main valve body 2 rises accordingly, thereby pushing the roller 52 of the side extrusion element 5 to rotate. The roller 52 and the second pressure-bearing inclined surface 22 of the main valve body 2 roll and rub against each other. On the one hand, the upward thrust of the second pressure-bearing inclined surface 22 on the roller 52 is converted into the rotational kinetic energy of the roller 52, preventing the side extrusion element 5 from blocking the upward movement of the main valve body 2. On the other hand, it further reduces the friction between them and reduces the generation of friction particles. In order to further reduce the friction, the contact area between the roller 52 and the second pressure-bearing inclined surface 22 can be reduced, for example, by reducing the middle diameter of the roller 52 so that this part does not contact the second pressure-bearing inclined surface 22. Of course, this application does not impose specific restrictions on the shape and installation structure of the side extrusion member 5. Adaptive adjustments can be made according to the above shape and installation method to ensure the extrusion effect on the main valve body 2 and reduce friction.

[0064] In one specific embodiment, a dust collection groove 15 is provided on the sealing surface 12 of the cavity between the hole and the sealing ring 232 for collecting trace amounts of fine particulate matter inside the cavity. The dust collection groove can be set as an annular shape or any other shape that can collect fine particulate matter; this application does not impose any specific limitations.

[0065] The auxiliary valve body 3 is connected to an external vacuum inlet. The vacuum inlet pushes the auxiliary valve body 3 to move in a straight line, which in turn pushes the main valve body 2 to move in a straight line and make slight up-and-down movements, thus achieving ultra-high vacuum isolation of the cavity. Preferably, the auxiliary valve body 3 is suspended within the strip groove 14 and does not contact the main components, especially not the bottom of the strip groove. Therefore, it will not generate friction between the main components 1 during movement, thus preventing the formation of particulate matter.

[0066] Inside the cavity of the main component 1, a top extrusion member 6 is installed above the auxiliary valve body 3. The top extrusion member 6 presses the auxiliary valve body 3 downward. In the vacuum isolation state, the top extrusion member 6 and the side extrusion member 5 cooperate to fix the auxiliary valve body 3, preventing the auxiliary valve body 3 from loosening and ensuring the reliability of vacuum isolation.

[0067] The top extruder 6 has a similar structure to the side extruder 5, and also includes rollers 52 that rotate around a shaft 51. Both ends of the shaft 51 are fixed to the cavity by set screws 53. When the auxiliary valve body 3 moves horizontally, the top extruder 6 and the top surface of the auxiliary valve body 3 experience rolling friction, reducing the frictional force between them. In some preferred embodiments, the surfaces of the two rollers 52 are gold-plated, and the surfaces of the first pressure-bearing inclined surface 21 and the second pressure-bearing inclined surface 22 are also gold-plated, thereby further reducing frictional particles generated when the rollers 52 roll.

[0068] Another embodiment of this application provides a scanning electron microscope, which includes an electron gun, a vacuum system, and other necessary modules known in the art, such as photoelectric / electromagnetic modules, signal collection and processing modules, display systems, recording systems, etc. The vacuum system includes the vacuum isolation device described in the above embodiments. The electron gun is positioned above the cavity of the vacuum isolation device, and other electron microscope modules are positioned below the cavity. The vacuum isolation device is used to intermittently seal the electron beam channel of the electron gun to form a vacuum-sealed cavity. When the vacuum inlet moves the auxiliary valve body 3 horizontally to the right, the hole in the middle of the main component 1 is open. The electron beam emitted by the electron gun under high voltage passes through this hole, then through various apertures, magnetic lenses, deflectors, etc., and finally strikes the sample surface.

[0069] Because the vacuum requirement for the electron gun in the electron gun barrel is very high, at least an order of magnitude higher than that of other series modules (such as other modules below the main component), and because other series modules contain other parts with high outgassing rates, such as rubber parts, their ultimate vacuum cannot reach the vacuum level of the electron gun's working chamber. Vacuuming these chambers would take too long, wasting resources. Therefore, the vacuum level of the electron gun is separated from that of other series modules by pressure differential. When other series modules experience vacuum issues, complete vacuum isolation is achieved through a vacuum isolation device.

[0070] Based on this, an aperture 7 is installed at the corresponding position of the hole on the bottom of the main component 1 to separate the vacuum sealing chamber of the electron gun from other modules by pressure difference. The aperture 7 is located between the upper and lower cavities and is locked by a locking ring threaded into the main component 1. Small holes are provided at the positions of the aperture 7 and the hole in the main component 1. The vacuum degree of the vacuum chamber above the aperture 7 is about one order of magnitude higher than that of the vacuum chamber below it. The principle of this structure is similar to installing a valve on a water pipe, where a pressure difference is automatically formed before and after the valve.

[0071] The working principle of this embodiment is as follows:

[0072] When vacuum isolation of the electron gun is required, the vacuum inlet drives the auxiliary valve body 3 to move to the left (i.e., in the direction of the side extrusion member 5). The extrusion slope 31 of the auxiliary valve body 3 pushes the main valve body 2 to move synchronously until the main valve body 2 abuts the side extrusion member 5. The left and right sides of the main valve body 2 are simultaneously squeezed downward by the side extrusion member 5 and the auxiliary valve body 3. The elastic member 4 is squeezed downward by the pressure block 24 and deformed, so that the sealing ring 232 is pressed on the sealing surface 12 to achieve a reliable seal. The connecting part 242 of the pressure block 24 is located on the right side of the waist-shaped hole 43 of the elastic member.

[0073] When performing electron beam scanning, the vacuum isolation of the electron gun needs to be released. The vacuum inlet drives the auxiliary valve body 3 to move to the right. The waist-shaped hole 43 of the elastic element 4 gives the auxiliary valve body 3 a certain degree of freedom in the horizontal direction. That is, in the initial stage of the auxiliary valve body 3 moving to the right, the pressure block 24, the connecting piece 242 and the main valve body 2 are temporarily held above the hole, so that the auxiliary valve body 3 releases the main valve body 2. At the same time, the first end 41 of the elastic element 4 releases the deformation stress and pushes the main valve body 2 upward, so that it is separated from the sealing surface 12. The roller of the side extrusion piece 5 is pushed by the second pressure inclined surface and rolls.

[0074] As the auxiliary valve body 3 continues to move to the right, the connector 242 moves to the left side of the oblong hole 43. The oblong hole 43 pulls the connector 242, the pressure block 24, and the main valve body 2 to move to the right together. During this process, the main valve body 2 is continuously pushed up by the elastic element 4. Therefore, during the process of the main valve body 2 forming / releasing vacuum isolation, the valve plate 231 and the sealing ring 232 basically do not contact the sealing surface 12, avoiding friction between them and the sealing surface 12. This prevents the generation of fine particles that could contaminate the vacuum environment inside the electron gun cavity, effectively protecting the tip of the electron gun and extending the service life of the equipment.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A vacuum isolation device, comprising a main component with a cavity, wherein the bottom of the cavity includes a sealing surface with a hole; characterized in that, The cavity is equipped with a main valve body, an auxiliary valve body, a side extrusion member, and an elastic member. The auxiliary valve body and the side extrusion member cooperate with each other to press and fix the main valve body from opposite sides of the main valve body and apply downward pressure to the main valve body, pressing the main valve body tightly against the sealing surface to achieve vacuum isolation of the cavity. The first end of the elastic element is fixed to the auxiliary valve body and the second end extends into the main valve body; a pressure block is installed in the main valve body, and the second end of the elastic element is pressed by the pressure block and deforms downward; when the elastic element moves backward relative to the main valve body along with the auxiliary valve body to release the deformation stress, it pushes the main valve body upward. The second end of the elastic element is provided with a waist-shaped hole, the length direction of which is parallel to the moving direction of the main valve body, and the pressure block is connected to the main valve body by a connector passing through the waist-shaped hole; When the auxiliary valve body retracts and resets, the waist-shaped hole of the elastic element causes the auxiliary valve body to loosen from the main valve body. The elastic element then quickly releases stress at the bottom of the pressure block and pushes the pressure block upward, thereby causing the main valve body to disengage from the sealing surface.

2. The vacuum isolation device according to claim 1, characterized in that, The bottom of the pressure block near the auxiliary valve body is formed with an arc-shaped transition surface, and the elastic element is in close contact with the transition surface when it deforms; The auxiliary valve body includes a mounting groove for positioning an elastic element, the bottom surface of which is formed with a slope for avoiding deformation of the elastic element, the outer side of which slopes downward.

3. The vacuum isolation device according to claim 1, characterized in that, The auxiliary valve body is driven to connect to the main valve body; the main valve body includes a first pressure-bearing inclined surface, and the auxiliary valve body includes a compression inclined surface adapted to the first pressure-bearing inclined surface; when the cavity is in a vacuum isolation state, the compression inclined surface presses down to press the first pressure-bearing inclined surface.

4. The vacuum isolation device according to claim 3, characterized in that, The side extrusion member is fixedly installed in the cavity; the main valve body also includes a second pressure-bearing inclined surface; The main valve body is configured such that it is driven by the auxiliary valve body to move toward the hole until its second pressure-bearing inclined surface is abutted by the side extrusion member and its first pressure-bearing inclined surface is abutted by the auxiliary valve body, at which point the main valve body presses down to seal the cover and seals the hole. The bottom of the main valve body is provided with a sealing ring for sealing the hole, and a dust collection groove is provided on the sealing surface of the cavity between the hole and the sealing ring.

5. The vacuum isolation device according to claim 4, characterized in that: The main valve body also includes a valve seat with a valve plate at the bottom, and the sealing ring is installed at the bottom of the valve plate; A fastening fitting is formed inside the valve seat above the valve plate, and the connecting member is fixedly connected to the fastening fitting and the pressure block.

6. The vacuum isolation device according to claim 5, characterized in that: The connecting component is a screw, and the fastening component is a stud with internal threads. The screw is screwed onto the stud to lock the pressure block. Alternatively, the connector is a snap-fit, and the fastening fitting is a slotted seat, with the connector snapping onto the seat to lock the pressure block.

7. The vacuum isolation device according to claim 4, characterized in that: The auxiliary valve body is connected to a vacuum inlet for driving the movement of the auxiliary valve body. A top extrusion member is installed above the auxiliary valve body in the cavity, and the top extrusion member extrudes the auxiliary valve body downward. Both the top extrusion member and the side extrusion member include rollers that rotate around an axis, and the axis is fixed to the main component; When the auxiliary valve body moves, there is rolling friction between the top extrusion member and the top surface of the auxiliary valve body; when the main valve body and the side extrusion member move in relation to each other, there is rolling friction between the roller and the second pressure inclined surface.

8. A scanning electron microscope, characterized in that: The device includes an electron gun and a vacuum system for providing a vacuum environment for the electron gun; the vacuum system includes a vacuum isolation device according to any one of claims 1 to 7 for intermittently sealing the electron beam channel to form a vacuum-sealed cavity for the electron gun; the electron gun is disposed above the cavity of the vacuum isolation device, and other modules are disposed below the cavity.

9. The scanning electron microscope according to claim 8, characterized in that: An aperture is installed at the bottom of the cavity, corresponding to the position of the hole, to separate the vacuum-sealed cavity of the electron gun from other modules by pressure difference.

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