Device and method for preventing backflow in PECVD vacuum pump pipeline

Abstract

The present invention discloses a device and method for preventing backflow in the PECVD vacuum pump pipeline, belonging to the field of semiconductor technology, which includes a first-stage limit diversion valve, a first-stage filtration diversion valve, a second-stage filtration diversion valve, and a second-stage limit diversion valve connected in sequence along the direction from the vacuum pump to the cavity of the PECVD equipment; the first-stage limit diversion valve includes a first valve body, a first central column, two first fan doors rotatably connected to the first central column, and a first stop bar; the first-stage filtration diversion valve includes a second valve body, a second central column, two second fan doors rotatably connected to the second central column, and a second stop bar; the second-stage filtration diversion valve includes a third valve body, a third central column, two third fan doors rotatably connected to the third central column, and a third stop bar; the second-stage limit diversion valve includes a fourth valve body, a fourth central column, two fourth fan doors, and a fourth stop bar. The present invention achieves the technical effect of being able to prevent gas from flowing back into the cavity, avoiding contamination of the cavity and scrapping of wafers.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology, and particularly relates to a device and method for preventing backflow of a PECVD vacuum pump pipeline. Background Art

[0002] PECVD, also known as plasma enhanced chemical vapor deposition, is widely used in wafer processing. At present, in semiconductor technology, a PECVD device is connected to a vacuum pump through a pipeline, and the vacuum pump discharges the process gas discharged from the PECVD device through the pipeline. However, in the event of abnormal situations such as voltage fluctuations or damage to the vacuum pump, the air pressure between the cavity of the PECVD device and the air pressure of the vacuum pump at both ends of the pipeline will be unbalanced, resulting in the backflow of the vacuum pipeline gas into the cavity of the PECVD device, causing cavity contamination and wafer scrapping.

[0003] Therefore, it is necessary to provide a new technical solution to solve the above technical problems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is the technical problem that gas is likely to flow back into the cavity, causing cavity contamination and wafer scrapping.

[0005] To solve the above technical problems, the present invention provides a device for preventing backflow in the PECVD vacuum pump pipeline. The device includes: a first limit and diversion valve, a first filter and diversion valve, a second filter and diversion valve, and a second limit and diversion valve, which are sequentially connected along the direction from the vacuum pump to the cavity of the PECVD device; the first limit and diversion valve includes a first valve body, a first central column, two first fan doors rotatably connected to the first central column, and a first stop bar; the first central column is connected to the first valve body, and the first stop bar is arranged on the first valve body, and the first stop bar is used to block the two first fan doors; the first filter and diversion valve includes a second valve body, a second central column, two second fan doors rotatably connected to the second central column, and a second stop bar, the second central column is connected to the second valve body; the second stop bar is arranged on the second valve body, and the second stop bar is used to block the two second fan doors, wherein a plurality of first through holes are provided on the second fan door; the second filter and diversion valve includes a third valve body, a third central column, two third fan doors rotatably connected to the third central column, and a third stop bar, the third central column is connected to the third valve body; the third stop bar is arranged on the third valve body, and the third stop bar is used to block the two third fan doors, wherein a plurality of second through holes are provided on the third fan door, and the diameter of the second through hole is smaller than the diameter of the first through hole; the second limit and diversion valve includes a fourth valve body, a fourth central column, two fourth fan doors rotatably connected to the fourth central column, and a fourth stop bar, the fourth central column is connected to the fourth valve body; the fourth stop bar is arranged on the fourth valve body, and the fourth stop bar is used to block the two fourth fan doors.

[0006] Optionally, the numerical range of the diameter of the first through hole is from 1.1 mm to 2 mm, and the numerical range of the diameter of the second through hole is from 0.5 mm to 1 mm.

[0007] Optionally, the two first fan doors are symmetrically distributed with respect to the first central column, the two second fan doors are symmetrically distributed with respect to the second central column, the two third fan doors are symmetrically distributed with respect to the third central column, and the two fourth fan doors are symmetrically distributed with respect to the fourth central column.

[0008] Optionally, the first stop bar is in a circular ring shape, the second stop bar is in a circular ring shape, the third stop bar is in a circular ring shape, and the fourth stop bar is in a circular ring shape.

[0009] Optionally, the first stop bar, the second stop bar, the third stop bar, and the fourth stop bar are respectively made of rubber material.

[0010] Optionally, the device further includes: pipe bodies are respectively arranged between the first valve body and the second valve body, between the second valve body and the third valve body, and between the third valve body and the fourth valve body. The first valve body, the second valve body, the third valve body, the fourth valve body and the pipe bodies are communicated to form an air passage.

[0011] Optionally, the first valve body, the second valve body, the third valve body, the fourth valve body and the pipe bodies are detachably connected by flanges.

[0012] According to another aspect of the present invention, the present invention further provides a method for preventing backflow in a PECVD vacuum pump pipeline. The method includes: sequentially arranging a first-stage limit flow guide valve, a first-stage filter flow guide valve, a second-stage filter flow guide valve and a second-stage limit flow guide valve between the vacuum pump and the cavity of the PECVD device; when the air pressure at one end close to the vacuum pump is greater than the air pressure at one end close to the cavity of the PECVD device, the generated air pressure difference is used to push the first-stage limit flow guide valve, the first-stage filter flow guide valve, the second-stage filter flow guide valve and the second-stage limit flow guide valve to be in a closed state respectively, so that the first-stage limit flow guide valve and the second-stage limit flow guide valve respectively block the gas flowing back towards the cavity of the PECVD device, and the gas is filtered by the first-stage filter flow guide valve and the second-stage filter flow guide valve respectively; when the air pressure at one end close to the vacuum pump is less than the air pressure at one end close to the cavity of the PECVD device, the generated air pressure difference drives the first-stage limit flow guide valve, the first-stage filter flow guide valve, the second-stage filter flow guide valve and the second-stage limit flow guide valve to be in an open state respectively, so that the gas flows from the cavity of the PECVD device through the first-stage limit flow guide valve, the first-stage filter flow guide valve, the second-stage filter flow guide valve and the second-stage limit flow guide valve into the vacuum pump in sequence.

[0013] Optionally, the filtering of the gas by the first-stage filter flow guide valve and the second-stage filter flow guide valve respectively includes: performing a primary filtering on the gas by the first-stage filter flow guide valve to remove the first type of particles; performing a secondary filtering on the gas after removing the large particles by the second-stage filter flow guide valve to remove the second type of particles, wherein the diameter of the first type of particles is greater than the diameter of the second type of particles.

[0014] Optionally, the diameter of the first type of particles is greater than a first filtering value, and the numerical range of the first filtering value is 1.1 mm to 2 mm; the diameter of the second type of particles is greater than a second filtering value, and the numerical range of the second filtering value is 0.5 mm to 1 mm.

[0015] Beneficial effects:

[0016] The present invention provides a device for preventing backflow in the PECVD vacuum pump pipeline. The device includes a first-stage limit diversion valve, a first-stage filter diversion valve, a second-stage filter diversion valve, and a second-stage limit diversion valve connected in sequence along the direction from the vacuum pump to the cavity of the PECVD equipment. In the first-stage limit diversion valve, a first central column is connected to a first valve body, two first fan doors are respectively rotatably connected to the first central column, and a first stop bar is arranged on the first valve body. The first stop bar is used to block the two first fan doors. In the first-stage filter diversion valve, a second central column is connected to a second valve body, two second fan doors are respectively rotatably connected to the second central column, and a second stop bar is arranged on the second valve body. The second stop bar is used to block the two second fan doors, and multiple first through holes are arranged on the second fan doors. In the second-stage filter diversion valve, a third central column is connected to a third valve body, two third fan doors are rotatably connected to the third central column, and a third stop bar is arranged on the third valve body. The third stop bar is used to block the two third fan doors, and multiple second through holes are arranged on the third fan doors. The diameter of the second through holes is smaller than that of the first through holes. In the second-stage limit diversion valve, a fourth central column is connected to a fourth valve body, two fourth fan doors are respectively rotatably connected to the fourth central column, and a fourth stop bar is arranged on the fourth valve body. The fourth stop bar is used to block the two fourth fan doors. In the event of an abnormal situation such as voltage fluctuation or damage to the vacuum pump, the air pressure at the end close to the vacuum pump will be greater than the air pressure at the end close to the cavity of the PECVD equipment. At this time, the pressure difference between the two ends of the vacuum pump and the PECVD equipment will push the two first fan doors in the first-stage limit diversion valve to rotate around the first central column. The first stop bar blocks the two first fan doors into a flat state, and the first-stage limit diversion valve initially restricts the gas flow and prevents backflow. Then, the two second fan doors in the first-stage filter diversion valve rotate around the second central column, and the second stop bar blocks the two second fan doors into a flat state to remove large particles in the gas through the first through holes on the second fan doors. Subsequently, the two third fan doors in the second-stage filter diversion valve rotate around the third central column, and the third stop bar blocks the two third fan doors into a flat state to remove small particles in the gas through the second through holes on the third fan doors. Then, the two fourth fan doors in the second-stage limit diversion valve rotate around the fourth central column, and the fourth stop bar blocks the two fourth fan doors into a flat state. The second-stage limit diversion valve performs secondary air pressure isolation and prevents gas backflow, thereby preventing gas and impurity particles in the gas from flowing back into the cavity of the PECVD equipment, ensuring the cleanliness and stability of the internal environment of the cavity, and avoiding contamination or damage to sensitive components such as wafers. Thus, the technical effect of preventing gas from flowing back into the cavity and avoiding contamination of the cavity and wafer scrapping is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a schematic structural diagram of a device for preventing backflow in the PECVD vacuum pump pipeline provided by an embodiment of the present invention.

[0019] Figure 2 It is a schematic structural diagram of a first-stage limit diversion valve in a device for preventing backflow in the PECVD vacuum pump pipeline provided by an embodiment of the present invention.

[0020] Figure 3 It is a schematic structural diagram of a first-stage filter diversion valve in a device for preventing backflow in the PECVD vacuum pump pipeline provided by an embodiment of the present invention.

[0021] Figure 4 It is a schematic structural diagram of a second-stage filter diversion valve in a device for preventing backflow in the PECVD vacuum pump pipeline provided by an embodiment of the present invention.

[0022] Figure 5 It is a schematic structural diagram of a second-stage limit diversion valve in a device for preventing backflow in the PECVD vacuum pump pipeline provided by an embodiment of the present invention.

[0023] Figure 6 It is a flowchart of a method for preventing backflow in the PECVD vacuum pump pipeline provided by an embodiment of the present invention. Detailed Embodiments

[0024] The following details the embodiments of the present application. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application.

[0025] In order to enable those skilled in the art of this technology to better understand the solutions of the present application, the following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present application.

[0026] In the embodiments of the present application, "at least one" means one or more; "a plurality" means two or more. In the description of the present application, terms such as "first", "second", "third", etc. are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying an order.

[0027] Reference to "an embodiment" or "some embodiments" described in this specification means that a specific feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, the terms "including", "comprising", "having" and their variants in this specification all mean "including but not limited to", unless otherwise specifically emphasized in other ways. It should be noted that in the embodiments of the present application, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone.

[0028] It should be pointed out that in the embodiments of the present invention, when a component is referred to as "fixed to" another component, it can be directly on the other component or there may also be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component at the same time. When a component is considered to be "disposed on" another component, it can be directly disposed on the other component or there may be an intermediate component at the same time. At the same time, in the embodiments of the present application, "connection" can also be understood as electrical connection, and the connection of two electrical components can be a direct or indirect connection between the two electrical components. For example, when A is connected to B, it can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components. The terms "vertical", "horizontal", "left", "right" and similar expressions used in the embodiments of the present invention are only for illustrative purposes and are not intended to limit the present invention.

[0029] An apparatus for preventing backflow in a PECVD vacuum pump pipeline provided in Embodiment 1 of the present invention is shown in Figures 1 to 5As shown in the figure, a device for preventing backflow in the PECVD vacuum pump pipeline provided by an embodiment of the present invention includes a first-stage limit diversion valve 1, a first-stage filter diversion valve 2, a second-stage filter diversion valve 3, and a second-stage limit diversion valve 4. The first-stage limit diversion valve 1, the first-stage filter diversion valve 2, the second-stage filter diversion valve 3, and the second-stage limit diversion valve 4 are connected in sequence along the direction from the vacuum pump to the cavity close to the PECVD device. The first-stage limit diversion valve 1 includes a first valve body 11, a first central column 12, two first fan doors 13, and a first stop bar 14. The first central column 12 is connected to the first valve body 11, the two first fan doors 13 are rotatably connected to the first central column 12, and the first stop bar 14 is arranged on the first valve body 11. The first stop bar 14 is used to block the two first fan doors 13. The first-stage filter diversion valve 2 includes a second valve body 21, a second central column 22, two second fan doors 23, and a second stop bar 24. The second central column 22 is connected to the second valve body 21, the two second fan doors 23 are rotatably connected to the second central column 22, and the second stop bar 24 is arranged on the second valve body 21. The second stop bar 24 is used to block the two second fan doors 23, and a plurality of first through holes 231 are arranged on the second fan door 23. The second-stage filter diversion valve 3 includes a third valve body 31, a third central column 32, two third fan doors 33, and a third stop bar 34. The third central column 32 is connected to the third valve body 31, the two third fan doors 33 are rotatably connected to the third central column 32, and the third stop bar 34 is arranged on the third valve body 31. The third stop bar 34 is used to block the two third fan doors 33, and a plurality of second through holes 331 are arranged on the third fan door 33. The diameter of the second through hole 331 is smaller than the diameter of the first through hole 231. The second-stage limit diversion valve 4 includes a fourth valve body 41, a fourth central column 42, two fourth fan doors 43, and a fourth stop bar 44. The fourth central column 42 is connected to the fourth valve body 41, the two fourth fan doors 43 are rotatably connected to the fourth central column 42, and the fourth stop bar 44 is arranged on the fourth valve body 41. The fourth stop bar 44 is used to block the two fourth fan doors 43.

[0030] Among them, between the cavity of the PECVD device and the vacuum pump, a secondary limit diversion valve 4, a secondary filter diversion valve 3, a primary filter diversion valve 2, and a primary limit diversion valve 1 are installed in sequence according to the gas flow direction from the cavity of the PECVD device to the vacuum pump. The vacuum pump is connected to the primary limit diversion valve 1, and the cavity of the PECVD device is connected to the secondary limit diversion valve 4. When there are voltage fluctuations in the system or the vacuum pump fails, resulting in abnormal air pressure, the primary limit diversion valve 1 will respond. At this time, the two first doors 13 rotate around the first central column 12 under the action of the air pressure difference until they are blocked by the first stop bar 14 and remain in the flat state, effectively restricting the gas flow and initially preventing the gas from flowing back into the cavity of the PECVD device. At the same time, the two second doors 23 of the primary filter diversion valve 2 also rotate to the flat state under the push of the air pressure. The first through holes 231 on the second doors 23 allow the gas to pass through, but can effectively intercept and block large particle impurities in the gas, such as dust, debris, etc., protecting the subsequent components from contamination. After the gas passes through the primary filtration of the primary filter diversion valve 2, it will enter the secondary filter diversion valve 3, where the third door 33 is further filtered through the second through holes 331 located on the third door 33 to remove tiny particles in the gas, such as tiny dust, microparticles, etc., ensuring that the gas is purer. And when the gas passes through the fourth door 43 of the secondary limit diversion valve 4, the fourth door 43 also rotates to the flat state under the action of the air pressure. The fourth stop bar 44 limits the fourth door 43, providing secondary air pressure isolation through the secondary limit diversion valve 4 and also serving as the final barrier to completely prevent the gas and any impurity particles carried by the gas from flowing back into the cavity of the PECVD device, ensuring the cleanliness and stability of the internal environment of the cavity.

[0031] In this embodiment, a first-stage limit and diversion valve 1, a first-stage filtration and diversion valve 2, a second-stage filtration and diversion valve 3, and a second-stage limit and diversion valve 4 are sequentially connected along the direction from the vacuum pump to the cavity of the PECVD device. In the first-stage limit and diversion valve 1, a first central column 12 is connected to a first valve body 11, two first fan doors 13 are respectively rotatably connected to the first central column 12, and a first stop bar 14 is arranged on the first valve body 11, and the first stop bar 14 is used to block the two first fan doors 13. In the first-stage filtration and diversion valve 2, a second central column 22 is connected to a second valve body 21, two second fan doors 23 are respectively rotatably connected to the second central column 22, and a second stop bar 24 is arranged on the second valve body 21, and the second stop bar 24 is used to block the two second fan doors 23, wherein a plurality of first through holes 231 are arranged on the second fan door 23. In the second-stage filtration and diversion valve 3, a third central column 32 is connected to a third valve body 31, two third fan doors 33 are rotatably connected to the third central column 32, and a third stop bar 34 is arranged on the third valve body 31, and the third stop bar 34 is used to block the two third fan doors 33, wherein a plurality of second through holes 331 are arranged on the third fan door 33, and the diameter of the second through hole 331 is smaller than the diameter of the first through hole 231. In the second-stage limit and diversion valve 4, a fourth central column 42 is connected to a fourth valve body 41, two fourth fan doors 43 are respectively rotatably connected to the fourth central column 42, and a fourth stop bar 44 is arranged on the fourth valve body 41, and the fourth stop bar 44 is used to block the two fourth fan doors 43. In this way, when an abnormal situation such as voltage fluctuation or damage of the vacuum pump occurs, the air pressure at the end close to the vacuum pump will be greater than the air pressure at the end close to the cavity of the PECVD device. At this time, the pressure difference between the two ends of the vacuum pump and the PECVD device will push the two first fan doors 13 in the first-stage limit and diversion valve 1 to rotate around the first central column 12, and the first stop bar 14 blocks the two first fan doors 13 into a flat state. The first-stage limit and diversion valve 1 initially limits the gas flow rate and prevents backflow; then the two second fan doors 23 in the first-stage filtration and diversion valve 2 rotate around the second central column 22, and the second stop bar 24 blocks the two second fan doors 23 into a flat state, and the large particles in the gas are removed through the first through holes 231 located on the second fan door 23; subsequently, the third fan doors 33 in the second-stage filtration and diversion valve 3 rotate around the third central column 32, and the third stop bar 34 blocks the two third fan doors 33 into a flat state, and the small particles in the gas are removed through the second through holes 331 located on the third fan door 33; then the two fourth fan doors 43 in the second-stage limit and diversion valve 4 rotate around the fourth central column 42, and the fourth stop bar 44 blocks the two fourth fan doors 43 into a flat state. The second-stage limit and diversion valve 4 performs secondary air pressure isolation and prevents the backflow of gas, thereby preventing the gas and the impurity particles in the gas from flowing back into the cavity of the PECVD device, ensuring the cleanliness and stability of the internal environment of the cavity, and avoiding the contamination or damage of sensitive components such as wafers. Thus, the technical effect of preventing the gas from flowing back into the cavity and avoiding the contamination of the cavity and the scrapping of the wafers is achieved.

[0032] As an implementation, the numerical range of the diameter of the first through-hole 231 is from 1.1 mm to 2 mm, and the numerical range of the diameter of the second through-hole 331 is from 0.5 mm to 1 mm. The first through-hole 231 and the second through-hole 331 can be respectively circular. Assuming the diameter of the first through-hole 231 is R1, then 1.1 mm ≤ R1 ≤ 2 mm, and the diameter of the second through-hole 331 is R2, then 0.5 mm ≤ R2 ≤ 1 mm. By setting the diameter of the first through-hole 231 between 1.1 mm and 2 mm, large particle impurities in the gas, such as dust and debris, can be effectively removed while ensuring the smoothness of gas flow. By setting the diameter of the second through-hole 331 between 0.5 mm and 1 mm, the filtering effect can be further refined to remove tiny particles in the gas, ensuring that the gas entering the PECVD equipment cavity is purer. When voltage fluctuations or vacuum pump damage occur, due to the specific size limitations of the first through-hole 231 and the second through-hole 331, the filtering effect will be more significant, further improving the cleanliness of the internal environment of the cavity and effectively avoiding the contamination or damage of sensitive components such as wafers.

[0033] In some embodiments, the two first fan doors 13 are symmetrically distributed with respect to the first central column 12, the two second fan doors 23 are symmetrically distributed with respect to the second central column 22, the two third fan doors 33 are symmetrically distributed with respect to the third central column 32, and the two fourth fan doors 43 are symmetrically distributed with respect to the fourth central column 42. By symmetrically distributing the two first fan doors 13 with respect to the first central column 12, the two second fan doors 23 with respect to the second central column 22, the two third fan doors 33 with respect to the third central column 32, and the two fourth fan doors 43 with respect to the fourth central column 42, the stability of the structure can be enhanced, so that under the action of the pressure difference, each fan door can be evenly stressed and rotate synchronously, which is beneficial to improving the overall response speed and sealing effect of the device. When an abnormal situation occurs, the symmetrically distributed fan doors can more effectively block the reverse flow of gas, and gradually remove impurities in the gas through the multi-stage filter diversion valves to ensure the cleanliness and stability of the PECVD equipment cavity.

[0034] In some embodiments, the first retaining strip 14 is circular, the second retaining strip 24 is circular, the third retaining strip 34 is circular, and the fourth retaining strip 44 is circular. By respectively setting the first retaining strip 14, the second retaining strip 24, the third retaining strip 34, and the fourth retaining strip 44 to be circular, it is beneficial to improve the durability and sealing performance of the retaining strips, effectively blocking the offset of the fan doors during rotation. For example, the first retaining strip 14 will fit more closely with the first fan door 13, the second retaining strip 24 will fit more closely with the second fan door 23, the third retaining strip 34 will fit more closely with the third fan door 33, and the fourth retaining strip 44 will fit more closely with the fourth fan door 43, enhancing the anti-backflow ability of the device.

[0035] In some embodiments, the first retaining strip 14, the second retaining strip 24, the third retaining strip 34, and the fourth retaining strip 44 are respectively made of rubber material. By making the first retaining strip 14, the second retaining strip 24, the third retaining strip 34, and the fourth retaining strip 44 all of rubber material, the good elasticity and sealing performance of the rubber material enable it to deform under pressure and closely adhere to the valve body and the fan door, effectively preventing gas leakage. In addition, the rubber material also has certain wear resistance and corrosion resistance, which can extend the service life of the device. In case of an abnormal situation, the retaining strip made of rubber material can quickly respond and closely adhere to the fan door to form an effective sealing barrier. At the same time, through the blockage of the rubber retaining strip, each stage of the limit flow guiding valve can effectively isolate the gas and the impurity particles in the gas, prevent the gas from flowing back into the cavity, and avoid causing cavity pollution and wafer scrapping.

[0036] In some embodiments, a device for preventing backflow in a PECVD vacuum pump pipeline provided in Embodiment 1 of the present invention further includes pipes 5 respectively arranged between the first valve body 11 and the second valve body 21, between the second valve body 21 and the third valve body 31, and between the third valve body 31 and the fourth valve body 41. The first valve body 11, the second valve body 21, the third valve body 31, the fourth valve body 41, and the pipe 5 are connected to form an air passage. For example, by connecting the first valve body 11, the second valve body 21, the third valve body 31, and the fourth valve body 41 through the pipe 5 to form a complete air passage, the pipe 5 not only ensures the physical connection between each stage of the valve body, but also enables the gas to flow smoothly in the entire device to form a continuous air passage. In case of an abnormal situation such as voltage fluctuation or damage of the vacuum pump, the air pressure at the end close to the vacuum pump will increase, pushing the fan door in each stage of the flow guiding valve to rotate around the central column. At the same time, due to the existence of the pipe 5, the gas can sequentially pass through the first-stage limit flow guiding valve 1, the first-stage filtering flow guiding valve 2, the second-stage filtering flow guiding valve 3, and the second-stage limit flow guiding valve 4 along the air passage. At each stage, the corresponding retaining strip will block the fan door into a flat state, restricting the gas flow and preventing backflow. At the same time, the through holes in the first-stage filtering flow guiding valve 2 and the second-stage filtering flow guiding valve 3 will respectively remove large-particle and small-particle impurities in the gas, avoiding causing cavity pollution of the PECVD equipment.

[0037] In some embodiments, the first valve body 11, the second valve body 21, the third valve body 31, the fourth valve body 41, and the pipe 5 are detachably connected by flanges 6. By connecting the first valve body 11, the second valve body 21, the third valve body 31, the fourth valve body 41, and the pipe 5 all through flanges 6, it is not only convenient for installation and disassembly, but also improves the flexibility and maintainability of the device. For example, when cleaning is required, the first valve body 11, or the second valve body 21, or the third valve body 31, or the fourth valve body 41, or the pipe 5 can be conveniently disassembled to discharge the large-particle or small-particle impurities accumulated therein.

[0038] To elaborate on a method for preventing backflow in the PECVD vacuum pump pipeline provided by the present invention, in the above-mentioned First Embodiment, a detailed description of a device for preventing backflow in the PECVD vacuum pump pipeline was given. Based on the same inventive concept, the present application also provides a method for preventing backflow in the PECVD vacuum pump pipeline, as detailed in the Second Embodiment.

[0039] Please refer to Figure 6 , Figure 6 which is a flowchart of a method for preventing backflow in the PECVD vacuum pump pipeline provided by an embodiment of the present invention. The Second Embodiment of the present invention provides a method for preventing backflow in the PECVD vacuum pump pipeline, and the method includes the following steps:

[0040] Step S100: Sequentially arrange a first-stage limit flow guiding valve 1, a first-stage filtering flow guiding valve 2, a second-stage filtering flow guiding valve 3, and a second-stage limit flow guiding valve 4 between the vacuum pump and the cavity of the PECVD device;

[0041] Step S200: When the air pressure at the end close to the vacuum pump is greater than the air pressure at the end close to the cavity of the PECVD device, the generated pressure difference drives the first-stage limit flow guiding valve 1, the first-stage filtering flow guiding valve 2, the second-stage filtering flow guiding valve 3, and the second-stage limit flow guiding valve 4 to be in the closed state respectively, so that the first-stage limit flow guiding valve 1 and the second-stage limit flow guiding valve 4 respectively block the gas flowing back in the direction towards the cavity of the PECVD device, and the gas is filtered by the first-stage filtering flow guiding valve 2 and the second-stage filtering flow guiding valve 3 respectively;

[0042] Step S300: When the air pressure at the end close to the vacuum pump is less than the air pressure at the end close to the cavity of the PECVD device, the generated pressure difference drives the first-stage limit flow guiding valve 1, the first-stage filtering flow guiding valve 2, the second-stage filtering flow guiding valve 3, and the second-stage limit flow guiding valve 4 to be in the open state respectively, so that the gas flows from the cavity of the PECVD device into the vacuum pump sequentially through the first-stage limit flow guiding valve 1, the first-stage filtering flow guiding valve 2, the second-stage filtering flow guiding valve 3, and the second-stage limit flow guiding valve 4.

[0043] Among them, a first-stage limit flow guiding valve 1, a first-stage filtering flow guiding valve 2, a second-stage filtering flow guiding valve 3, and a second-stage limit flow guiding valve 4 are sequentially installed in the direction of the vacuum pump approaching the cavity of the PECVD equipment. The first-stage limit flow guiding valve 1, the first-stage filtering flow guiding valve 2, the second-stage filtering flow guiding valve 3, and the second-stage limit flow guiding valve 4 are kept open under normal working conditions, allowing gas to flow smoothly from the cavity of the PECVD equipment to the vacuum pump for discharge. When the system encounters abnormal conditions such as voltage fluctuations or damage to the vacuum pump, resulting in a sudden increase in the air pressure at the end close to the vacuum pump, exceeding the air pressure at the end close to the cavity of the PECVD equipment, the pressure difference will immediately drive each stage of the valve to respond. At this time, the first-stage limit flow guiding valve 1 and the second-stage limit flow guiding valve 4 will quickly close, effectively blocking the backflow of gas towards the cavity of the PECVD equipment. At the same time, the first-stage filtering flow guiding valve 2 and the second-stage filtering flow guiding valve 3 will respectively filter the backflow gas preliminarily and further, removing large particles and small particle impurities respectively. On the contrary, when the air pressure at the end close to the vacuum pump is lower than the air pressure at the end close to the cavity of the PECVD equipment, the system returns to normal at this time, and each stage of the valve will automatically open under the action of the pressure difference, and the gas will flow smoothly along the original path to the vacuum pump again.

[0044] In some embodiments, the filtering of the gas by the first-stage filtering flow guiding valve 2 and the second-stage filtering flow guiding valve 3 respectively includes: performing a primary filtration on the gas through the first-stage filtering flow guiding valve 2 to remove the first type of particles; performing a secondary filtration on the gas after removing the large particles through the second-stage filtering flow guiding valve 3 to remove the second type of particles, where the diameter of the first type of particles is greater than the diameter of the second type of particles. That is, when the gas flows from the cavity of the PECVD equipment to the vacuum pump and passes through the first-stage filtering flow guiding valve 2, two second fan doors 23 inside the valve rotate around the second central column 22 under the action of the pressure difference, and are blocked by the second stop bar 24 to be in a flat state. While ensuring the sealing of the valve, it allows the gas to pass through. When the gas passes through the first through hole 231 on the second fan door 23, it will experience a primary filtration process. The primary filtration process mainly removes the first type of particles in the gas. The first type of particles refers to relatively large particles, which can effectively reduce the large particles that may accumulate in the subsequent pipelines and the vacuum pump, reducing the risk of blockage. The gas after the primary filtration will continue to flow to the second-stage filtering flow guiding valve 3. In the second-stage filtering flow guiding valve 3, two third fan doors 33 also rotate around the third central column 32 under the action of the pressure difference, and are blocked by the third stop bar 34 to be in a flat state. The gas passes through the second through hole 331 on the third fan door 33 for secondary filtration to remove the second type of particles remaining after the filtration of the first type of particles, that is, small particles with a diameter smaller than the first type of particles, which is beneficial to further improve the cleanliness of the gas and protect the vacuum pump and subsequent processing equipment from damage by tiny particles.

[0045] In some embodiments, the diameter of the first type of particles is greater than a first filtration value, and the numerical range of the first filtration value is from 1.1 mm to 2 mm; the diameter of the second type of particles is greater than a second filtration value, and the numerical range of the second filtration value is from 0.5 mm to 1 mm. For example, effectively removing particles with a diameter greater than 1.1 mm in the primary filtration stage will reduce the subsequent filtration burden. In the secondary filtration stage, smaller particles with a diameter greater than 0.5 mm will be further removed to ensure that the gas cleanliness entering the vacuum pump finally meets the requirements. Precise filtration control will directly improve the overall performance and stability of the system.

[0046] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A device for preventing backflow in a PECVD vacuum pump pipeline, characterized in that, The device includes: a first limit diversion valve, a first filter diversion valve, a second filter diversion valve, and a second limit diversion valve connected in sequence along the direction from the vacuum pump to the cavity of the PECVD device; the first limit diversion valve includes a first valve body, a first central column, two first fan doors rotatably connected to the first central column, and a first stop bar; the first central column is connected to the first valve body, the first stop bar is arranged on the first valve body, and the first stop bar is used to block the two first fan doors; the first filter diversion valve includes a second valve body, a second central column, two second fan doors rotatably connected to the second central column, and a second stop bar, the second central column is connected to the second valve body; the second stop bar is arranged on the second valve body, and the second stop bar is used to block the two second fan doors, wherein a plurality of first through holes are provided on the second fan doors; the second filter diversion valve includes a third valve body, a third central column, two third fan doors rotatably connected to the third central column, and a third stop bar, the third central column is connected to the third valve body; the third stop bar is arranged on the third valve body, and the third stop bar is used to block the two third fan doors, wherein a plurality of second through holes are provided on the third fan doors, and the diameter of the second through holes is smaller than the diameter of the first through holes; the second limit diversion valve includes a fourth valve body, a fourth central column, two fourth fan doors rotatably connected to the fourth central column, and a fourth stop bar, the fourth central column is connected to the fourth valve body; the fourth stop bar is arranged on the fourth valve body, and the fourth stop bar is used to block the two fourth fan doors, the two first fan doors are symmetrically distributed relative to the first central column, the two second fan doors are symmetrically distributed relative to the second central column, the two third fan doors are symmetrically distributed relative to the third central column, the two fourth fan doors are symmetrically distributed relative to the fourth central column, and the device further includes: pipe bodies are respectively arranged between the first valve body and the second valve body, between the second valve body and the third valve body, and between the third valve body and the fourth valve body, and the first valve body, the second valve body, the third valve body, the fourth valve body and the pipe bodies are communicated to form an air passage.

2. The device for preventing backflow in the PECVD vacuum pump pipeline according to claim 1, wherein: The numerical range of the diameter of the first through holes is from 1.1 mm to 2 mm, and the numerical range of the diameter of the second through holes is from 0.5 mm to 1 mm.

3. The device for preventing backflow in the PECVD vacuum pump pipeline according to claim 1, characterized in that: The first stop bar is in a circular ring shape, the second stop bar is in a circular ring shape, the third stop bar is in a circular ring shape, and the fourth stop bar is in a circular ring shape.

4. The device for preventing backflow in the PECVD vacuum pump pipeline according to claim 1, characterized in that: The first stop bar, the second stop bar, the third stop bar, and the fourth stop bar are respectively made of rubber material.

5. The device for preventing backflow in the PECVD vacuum pump pipeline according to claim 1, characterized in that: The first valve body, the second valve body, the third valve body, the fourth valve body and the pipe bodies are detachably connected by flanges.

6. A method for using a device for preventing backflow in a PECVD vacuum pump pipeline as described in claim 1, characterized in that, The method includes: Sequentially arranging a first limit diversion valve, a first filter diversion valve, a second filter diversion valve, and a second limit diversion valve between the vacuum pump and the cavity of the PECVD device; When the air pressure at one end close to the vacuum pump is greater than the air pressure at one end close to the cavity of the PECVD equipment, the generated air pressure difference drives the first-stage limit diversion valve, the first-stage filter diversion valve, the second-stage filter diversion valve, and the second-stage limit diversion valve to be in the closed state respectively, so that the first-stage limit diversion valve and the second-stage limit diversion valve respectively block the gas flowing back in the direction close to the cavity of the PECVD equipment, and the gas is filtered by the first-stage filter diversion valve and the second-stage filter diversion valve respectively; When the air pressure at one end close to the vacuum pump is less than the air pressure at one end close to the cavity of the PECVD equipment, the generated air pressure difference drives the first-stage limit diversion valve, the first-stage filter diversion valve, the second-stage filter diversion valve, and the second-stage limit diversion valve to be in the open state respectively, so that the gas flows from the cavity of the PECVD equipment into the vacuum pump through the first-stage limit diversion valve, the first-stage filter diversion valve, the second-stage filter diversion valve, and the second-stage limit diversion valve in sequence.

7. The method for preventing backflow in the PECVD vacuum pump pipeline according to claim 6, characterized in that, The filtering of the gas by the first-stage filter diversion valve and the second-stage filter diversion valve respectively includes: the gas is first filtered by the first-stage filter diversion valve to remove the first type of particles; the gas after removing the large particles is secondarily filtered by the second-stage filter diversion valve to remove the second type of particles, where the diameter of the first type of particles is greater than the diameter of the second type of particles.

8. The method for preventing backflow in the PECVD vacuum pump pipeline according to claim 7, characterized in that: The diameter of the first type of particles is greater than the first filtering value, and the numerical range of the first filtering value is from 1.1 mm to 2 mm; the diameter of the second type of particles is greater than the second filtering value, and the numerical range of the second filtering value is from 0.5 mm to 1 mm.

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