A DC dust removal device for the front stage of a vacuum pump in a semiconductor process
By designing a vacuum pump pre-stage DC dust removal device in the semiconductor manufacturing process, and using condensation and electrostatic repulsion technologies to remove particulate matter, the problem of particulate matter pollution in semiconductor manufacturing is solved, efficient and low-cost removal effect is achieved, and the vacuum system equipment is protected.
Patent Information
- Application Number
- CN202410273092.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-11
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2044-03-11
AI Technical Summary
In semiconductor manufacturing processes, the generation of micro-nano-scale particulate matter causes contamination of vacuum chambers and exhaust systems, affecting equipment life and production efficiency. It is difficult for the prior art to effectively remove these particulate matter, especially the proportion of particulate matter generated in the flaking process is more likely to be more likely to be used. The higher the rise leads to increased system burden and common methods such as adding filter devices or cold traps have limited effects.
Design a vacuum pump pre-stage DC dust removal device, including a condensation module, an electrostatic repulsion module and a collection module, which cools the particulate matter by cooling the condensation module. The electrostatic repulsion module uses plasma to charge the particulate matter and guides it to the collection tank of the collection module through an electrostatic field. Achieve efficient removal.
The efficiency of removing particulate matter in residual gas in semiconductor manufacturing processes is as high as 99.2%, protecting vacuum system equipment, reducing system maintenance costs, and the device is simple in structure, convenient in operation and low in cost, making it suitable for industrial applications.
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Figure CN117960379B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of particle removal in semiconductor manufacturing processes, and relates to a direct current dust removal device for the front stage of a vacuum pump in a semiconductor process flow. Background Art
[0002] At present, vacuum systems in the semiconductor manufacturing field are Figure 1 As shown: the vacuum pump is connected to the vacuum chamber through the front vacuum pipeline and maintains the vacuum environment in the chamber; the vacuum pump exhaust is connected to the tail gas treatment equipment through the exhaust pipeline. After the tail gas treatment equipment treats the harmful gases, it is discharged into the factory's main factory exhaust pipeline through the tail gas. Semiconductor products are processed in the vacuum chamber, and various physical and chemical reactions occur in the chamber to convert gas and solid, such as: SiH4 (gaseous) + NH3 (gaseous) → Si3N4 (solid) + H2 (gaseous). Moreover, most of the time, the chemical reaction is not complete, resulting in various by-products, which is also the main source of particulate matter.
[0003] In the semiconductor manufacturing process, many micro-nano particles will inevitably be formed. The appearance of these particles not only reduces the yield of the wafer, but also pollutes the vacuum chamber and the exhaust system. Therefore, removing particle pollutants is a key link in the semiconductor manufacturing process. Particles come from the factory processing and production environment on the one hand, and solid particles of various sizes generated by complex gas phase reactions in the tape-out process on the other hand. Among them, particles generated in the tape-out process are the main source. According to statistics, for the production of 4M DRAM with a design line width of 1mm, 50% of the polluted particles are generated by the factory processing and production environment, and the remaining 50% of the particles are generated by the tape-out process. In the production of 16MDRAM with a line width of 0.5mm, the particles generated by the tape-out process increased to 60%; in the production of 64M DRAM with a line width of 0.35mm, the particles generated by the tape-out process increased to 75%; and in the production of 256M DRAM with a line width of 0.25mm, the particles generated by the tape-out process will be as high as 90%, becoming the main source of pollution.
[0004] As mentioned above, particulate matter is mainly formed in the vacuum chamber, and the vacuum chamber is connected to the exhaust system. Therefore, particulate matter will inevitably enter the exhaust system with the residual gas after the gas phase reaction and pollute the exhaust system. On the one hand, particulate matter will be adsorbed on the wall of the pipe when passing through the exhaust pipe, and it is difficult to fall off, forming permanent pollution. On the other hand, particulate matter flowing through the exhaust pipe will eventually enter the vacuum pump and other vacuum equipment. These micro-nano particles pose a serious threat to the normal operation of the molecular pump. Since the molecular pump works continuously around the clock to maintain the vacuum degree in the vacuum chamber, particulate matter will continue to accumulate in the molecular pump, seriously affecting the life of the molecular pump. Under normal circumstances, the molecular pump needs to be shut down for maintenance every month to remove the particulate contaminants in the molecular pump. If these particulate matter cannot be removed in time, the molecular pump will be damaged. Whether it is shutting down for maintenance or replacing a new molecular pump, it will affect the continuous operation of the semiconductor manufacturing process and increase the system cost. Therefore, removing particulate matter in the exhaust system is a key technical issue in the current semiconductor manufacturing field.
[0005] By adding a filtering device, such as a screen, in front of the dry pump that maintains the vacuum system, particles can be filtered by controlling the aperture of the screen, but the screen will affect the pumping speed of the vacuum pump and there is a risk of clogging.
[0006] In the front vacuum pipeline, a cold trap is added to make the activated gas quickly condense or combine into particles for removal; this method also has certain problems, such as the excessive gas flow rate in the pipeline, which makes it difficult for the cold trap to play an effective role. The opposite idea is adopted, adding insulation function to the front vacuum pipeline and exhaust pipeline to maintain the high temperature of the pipeline, so as to achieve the purpose of suppressing the generation of particles. This method is more common, but practice shows that the particles generated in the chamber by this method will still accumulate in the subsequent vacuum system, thereby increasing the burden on the vacuum system and cannot fundamentally solve the problem.
[0007] The patent with publication number CN117357991A discloses a semiconductor production waste gas treatment process, which first performs pretreatment, introduces the object into the front mechanism to participate in the front dust removal treatment; then performs gas mixing treatment, introduces the object output by the front mechanism into the gas mixing mechanism to participate in the slow flow and speed reduction treatment; then performs purification treatment, introduces the object output by the gas mixing mechanism into the purification mechanism to participate in the plasma combustion purification treatment; then performs cooling treatment, introduces the object output by the purification treatment into the cooling mechanism for cooling treatment; finally performs discharge treatment, and discharges the object output by the cooling mechanism through the external discharge mechanism. This scheme is not only complex in structure, but also requires combustion treatment, which has certain safety hazards. Summary of the invention
[0008] The purpose of the present invention is to solve the key technical problem of how to remove process residual particulate matter in the semiconductor manufacturing field. A DC dust removal device for the front stage of a vacuum pump in a semiconductor process flow is proposed. The present invention has the advantages of easy operation, simple structure, ideal dust removal effect and low cost.
[0009] The technical solution of the present invention is:
[0010] A DC dust removal device for the front stage of a vacuum pump in a semiconductor process flow, characterized in that it comprises a condensation module, an electrostatic repulsion module and a collection module; the condensation module, the electrostatic repulsion module and the collection module are arranged vertically in sequence on the exhaust pipe between the vacuum chamber and the vacuum pump; the bottom of the collection module has a collection tank and an exhaust port; wherein,
[0011] The condensation module is used to cool the exhaust gas discharged from the vacuum chamber, and promote the condensation and growth of particles in the exhaust gas into particles, which then enter the electrostatic repulsion module;
[0012] The electrostatic repulsion module is used to form a free charge distribution area and an electrostatic field by using the generated plasma, so that the particulate matter in the input exhaust gas is charged when the exhaust gas flows through the free charge distribution area, and then the charged particulate matter is repelled and guided to move into the collection tank of the dust collection module by using the electrostatic field;
[0013] The exhaust port of the collection module is connected to the vacuum pump through an exhaust pipe, so as to discharge the residual gas after the particulate matter is filtered out through the vacuum pump.
[0014] Furthermore, the electrostatic repulsion module includes a cylinder B, in which a first spherical crown-shaped metal orifice plate and a second spherical crown-shaped metal orifice plate are arranged; wherein the first spherical crown-shaped metal orifice plate serves as a negative electrode, the second spherical crown-shaped metal orifice plate serves as a positive electrode, and the first spherical crown-shaped metal orifice plate is located below the second spherical crown-shaped metal orifice plate; the collection module includes a cylinder C, the bottom edge of the inner wall of the cylinder C is provided with the collection groove, and the central area is the exhaust port; the tops of the first spherical crown-shaped metal orifice plate and the second spherical crown-shaped metal orifice plate face upward; the first spherical crown-shaped metal orifice plate is used to The discharge breaks down the gas to generate plasma to form a free charge distribution area, and the plasma forms a sheath electric field on the inner wall surface of the cylinder B, the surface of the first spherical crown metal perforated plate and the surface of the second spherical crown metal perforated plate respectively. The sheath electric field on the surface of the first spherical crown metal perforated plate and the second spherical crown metal perforated plate is used to repel the charged particles and then slide toward the side wall of the cylinder B. The sheath electric field on the surface of the cylinder B is used to repel the charged particles and then move them away from the inner wall surface of the cylinder B and slide into the collection groove of the dust collection module.
[0015] Furthermore, the aperture of the metal holes on the first spherical crown shaped metal hole plate is not greater than 7 mm, the thickness of the first spherical crown shaped metal hole plate is 0.5 mm, and the grid radius is 3 mm; the aperture of the metal holes on the second spherical crown shaped metal hole plate is not greater than 7 mm, the thickness of the second spherical crown shaped metal hole plate is 0.5 mm, and the grid radius is 3 mm.
[0016] Furthermore, the curvature of the second spherical crown-shaped metal perforated plate is smaller than the curvature of the first spherical crown-shaped metal perforated plate.
[0017] Furthermore, the inner diameter of the cylinder B is 160 mm, the outer diameter is 165 mm, and the length is 300 mm. The height of the second spherical crown metal orifice plate is 40 mm, and the height of the first spherical crown metal orifice plate is 60 mm and the maximum diameter is 120 mm. The second spherical crown metal orifice plate is 100 mm away from the top of the cylinder B, and the vertical distance between the first spherical crown metal orifice plate and the second spherical crown metal orifice plate is 50 mm.
[0018] Furthermore, the collection module includes a cylinder C, the bottom of which is provided with a collection groove and an exhaust port; the width of the collection groove is 20 mm and the depth is 30 mm; the inner diameter of the cylinder C is smaller than the inner diameter of the cylinder B.
[0019] Furthermore, the first spherical crown metal orifice plate is electrically connected to the power supply system outside the cylinder B through the interface on the side wall of the cylinder B, and the second spherical crown metal orifice plate is grounded through the interface on the side wall of the cylinder B.
[0020] Furthermore, the power supply system outside the cylinder B is a DC negative pressure power supply.
[0021] Furthermore, the condensation module includes a cylinder A and a water cooling pipe, the upper end of the cylinder A is connected to the exhaust gas outlet of the vacuum chamber, and the lower end of the cylinder A is connected to the electrostatic repulsion module; the water cooling pipe is wound around the outer wall of the cylinder A to cool the exhaust gas.
[0022] The invention comprises a condensation module, an electrostatic repulsion module and a collection module. The three modules are sequentially arranged on a pipeline of a semiconductor manufacturing exhaust system, usually vertically arranged in sequence on an exhaust pipeline between a vacuum chamber and a vacuum pump.
[0023] The main function of the condensation module is to provide a transition buffer zone between the semiconductor manufacturing vacuum chamber and the electrostatic repulsion module, so that the residual gas can be cooled after being discharged from the vacuum chamber, promote the growth of particles, and reduce the particles generated again after the residual gas passes through the electrostatic repulsion module.
[0024] The electrostatic repulsion module is mainly used to generate uniform plasma and charge the particles, and then guide the movement of the particles through electrostatic repulsion. The electrodes used to generate plasma are two spherical crown-shaped metal perforated plates, which are placed up and down in the cylinder at a certain distance. The plasma is generated by DC glow discharge. The purpose of generating uniform plasma is to obtain a relatively uniform free charge distribution in space. When the residual gas particles flow through the uniform plasma, the free charges (electrons and ions) in the plasma will collide with the particles and adsorb on the surface of the particles to charge the particles. When the electron charging rate and the ion charging rate reach a balance, the amount of charge obtained by the particles reaches a stable level. Since the mass of electrons is much smaller than the mass of ions, the thermal velocity of electrons is much greater than the thermal velocity of ions. Therefore, particles usually adsorb more electrons and eventually become negatively charged. By adjusting the discharge parameters to change parameters such as electron density, the charge of the particles can be controlled. The energized spherical cap-shaped metal perforated plate will form a sheath on its surface in the plasma. When negatively charged particles reach the vicinity of the surface of the spherical cap-shaped metal perforated plate, the electric field in the sheath will repel the particles, causing them to move along the side of the spherical cap toward the cylindrical wall and eventually enter the dust collection module.
[0025] The main function of the collection module is to collect the particles from the guide module through the grooves set at the upper end of the metal cylinder. According to actual needs, groove structures of different shapes and sizes can be set. The particles repelled by the electric field move from the center of the pipeline to the side wall of the pipeline along the surface of the spherical crown metal orifice plate with the airflow and under the action of gravity. After passing through the electrostatic repulsion module, they naturally fall into the grooves of the collection module to achieve the collection of particles. The spherical crown metal orifice plate and the collection tank can be removed and cleaned regularly according to actual conditions.
[0026] The method of the present invention mainly comprises the following steps:
[0027] A. Three cylinders are provided, namely, cylinder A, cylinder B, and cylinder C. The cylinder A is connected to the exhaust system pipeline of the semiconductor manufacturing process through a flange, and is connected to the vertical pipeline between the vacuum chamber and the vacuum pump from top to bottom. The materials of the cylinder A, cylinder B, and cylinder C can be metal or glass.
[0028] B. Condensation module: A water cooling tube is arranged in the cylinder A and is wound around the cylinder A. Cold water is continuously passed through the water cooling tube so that the residual gas discharged from the semiconductor process chamber reacts fully and the particles grow completely.
[0029] C. Electrostatic repulsion module: In the cylinder B, two first spherical crown-shaped metal orifice plates and a second spherical crown-shaped metal orifice plates are arranged up and down and do not touch each other, which serve as negative electrodes and positive electrodes respectively, with the top of the tower facing upward and the bottom of the tower not touching the cylinder B. The first spherical crown-shaped metal orifice plate is connected to the power supply system outside the cylinder B through the interface on the side wall of the cylinder B as a negative pressure electrode, and the second spherical crown-shaped metal orifice plate is grounded through the interface on the side wall of the cylinder B as a grounding electrode.
[0030] D. The cylinder C includes a dust collection module. A groove is provided near the flange of the upper port of the cylinder C and is connected to the flange of the lower port of the cylinder B to collect particulate matter discharged from the cylinder B.
[0031] E. Turn on the power system, and when the residual gas from the semiconductor manufacturing vacuum chamber flows downward through the spherical crown metal orifice plate in the cylinder B, a discharge breakdown gas is generated, and a uniform plasma is obtained between the first spherical crown metal orifice plate and the second spherical crown metal orifice plate, and the required plasma environment is obtained by controlling the DC voltage of the first spherical crown metal orifice plate. When the particles in the residual gas flow downward through the plasma area formed in the cylinder B with the residual gas, the plasma quickly charges the particles, and the particles are electronegative. The plasma will diffuse around, and sheath layers will be generated on the surface of the cylinder B, the surface of the first spherical crown metal orifice plate, and the surface of the second spherical crown metal orifice plate.
[0032] F. When the electronegative particles continue to move downward with the airflow under the influence of gravity and approach the negatively charged spherical crown metal hole plate, the negatively charged particles are repelled by the surface electric field of the first spherical crown metal hole plate and the second spherical crown metal hole plate, slide down along the surface sheath of the spherical crown metal hole plate and approach the side wall of cylinder B. When the particles move to the groove of the flange on the cylinder C, they enter the groove, completing the collection process of the particles in the residual gas.
[0033] G. After a certain period of operation, take out the cylinder B and cylinder C and the first spherical crown metal perforated plate and the second spherical crown metal perforated plate from the exhaust pipe, clean the particles in the groove and on the surface, and reinstall them to continue the process of removing particles in the residual gas. To ensure the operation efficiency, a set of spare equipment can be prepared for rotation use.
[0034] The method of the present invention has a high efficiency in removing particulate matter from residual gas in semiconductor manufacturing process, which can not only achieve green environmental protection and reduce particulate matter emissions, but also protect the back-stage vacuum pump of the vacuum system to a great extent. The device designed by the method of the present invention can operate all year round, and the equipment cost is very low.
[0035] The sizes of the three cylinders described in step A can be set according to the actual exhaust pipe sizes of the factory.
[0036] The water cooling pipe provided in step B can cool the gas in cylinder A, promote the growth and condensation of residual chemical components in the residual gas into particulate matter, and improve the subsequent dust removal efficiency.
[0037] The main purpose of setting the spherical crown metal perforated plate in step C is to use the two spherical crown metal perforated plates to generate uniform plasma and charge the particles, so as to guide the subsequent movement trajectory of the charged particles, so that the particles move downward and to both sides along the surface sheath of the spherical crown metal perforated plate, and finally reach the groove of the cylinder C for collection. In step C, the first spherical crown metal perforated plate and the second spherical crown metal perforated plate are connected to the power supply and the ground respectively, with the purpose of generating uniform plasma by gas discharge between the first spherical crown metal perforated plate and the second spherical crown metal perforated plate. The power supply uses a DC negative voltage power supply, and a glow plasma is formed by discharge between the two spherical crown metal perforated plates.
[0038] In step D, the size of the groove provided on the upper flange of the metal cylinder C can be set as required. The larger the volume of the groove, the more particles can be collected, that is, the continuous working time of the particle removal device designed by the method is longer.
[0039] The plasma generated in step E contains electrons, positive ions, negative ions, and various active groups. When the particles enter the plasma, since the mass of electrons is much smaller than the mass of other particles and the speed of electron movement is much greater than the speed of other particles, the electrons first reach and adsorb on the surface of the particles. When the electron charging current and the charging current of other particles reach equilibrium, the charge of the particles basically reaches a steady state and is electronegative.
[0040] Step F is to utilize the surface electric field of the spherical crown metal hole plate to guide the negatively charged particles in step E into the upper flange groove of the cylinder B to complete the collection.
[0041] In step F, when the particles flow through the cylinder B from top to bottom with the residual gas, they are first charged in the plasma region, and then move along the surface of the spherical metal perforated plate toward the flange groove provided on the cylinder C during the downward movement.
[0042] In step G, since the generated plasma generates a sheath on the inner wall surface of the cylinder B, the sheath electric field exerts an electric field force on the electronegative particles away from the inner wall surface of the cylinder B, so the particles cannot reach the inner wall surface of the cylinder B, thereby avoiding the contamination of the cylinder B by the particles. The material of the cylinder B can be glass or metal.
[0043] The advantages of the present invention are as follows:
[0044] The present invention arranges three cylinders in series on the vertical exhaust pipe between the semiconductor process vacuum chamber and the back-stage vacuum pump; first installs a set of water cooling pipes outside the first cylinder A to ensure that the residual gas particles generated in the semiconductor manufacturing are fully condensed and the dust removal efficiency is improved; then uses DC discharge to generate uniform plasma in the second cylinder B, and when the particles flow through the plasma area with the residual gas, the charged particles in the plasma hit the particles and adsorb on their surface, making the particles negatively charged; when the negatively charged particles continue to flow downward through the charged spherical crown metal orifice plate in the second cylinder B, they are repelled by the surface electric field and guided to move along the surface of the spherical crown metal orifice plate toward the side wall of the cylinder, and finally enter the groove of the port flange set in the third cylinder C, so as to collect the particles. The efficiency of removing particles from the residual gas of semiconductor manufacturing by the present invention can reach 100% in theory, and the actual measured value is 99.2%. It is not only green and environmentally friendly, with no particle emission, but also can effectively protect the exhaust pipeline and the back-stage vacuum pump and other equipment. The residual gas particle removal device designed using the method has low cost and can be continuously operated in a factory, thus solving the residual gas particle pollution problem in current semiconductor manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS
[0045] Figure 1 This is a schematic diagram of a vacuum system in semiconductor manufacturing.
[0046] Figure 2 It is a structural schematic diagram of the present invention.
[0047] Figure numerals: 1-semiconductor process chamber; 2-particles; 3-cylinder A; 4-water cooling tube; 5-cylinder B; 6-ground electrode; 7-negative pressure electrode; 8-DC negative pressure power supply; 9-ground wire; 10-cylinder C; 11-collecting tank; 12-exhaust pipe; 13-vacuum pump. DETAILED DESCRIPTION
[0048] The present invention is further described in detail below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention but not to limit the scope of the present invention.
[0049] like Figure 2 As shown, the method for removing residual gas particles in semiconductor manufacturing provided by the present invention specifically includes the following steps:
[0050] The particles 2 in the semiconductor process chamber 1 will flow out with the residual gas and flow into the pre-set cylinder A. The cylinder A has an inner diameter of 160 mm, an outer diameter of 165 mm, and a length of 350 mm. It is made of metal and is connected to the exhaust pipe 12 at the upper end. A water cooling device, i.e., a water cooling pipe 4, is installed outside the cylinder A. The water cooling pipe 4 is an aluminum or copper pipe with a water outlet at the top and a water inlet at the bottom. Cold water at 5°C is continuously passed through the cylinder A for cooling.
[0051] Cylinder B is located below cylinder A and connected to cylinder A by flange. It is made of quartz, with an inner diameter of 160 mm, an outer diameter of 165 mm, and a length of 300 mm. Two spherical crown-shaped metal orifice plates are placed in parallel inside as electrodes, namely, ground electrode 6 and negative pressure electrode 7. Ground electrode 6 and negative pressure electrode 7 are made of metal, with a height of 40 mm and 60 mm respectively, and a maximum diameter of 120 mm. The curvature of ground electrode 6 is smaller than that of negative pressure electrode 7, and is fixed near the inner wall of cylinder A by a fixing device. Ground electrode 6 is 100 mm away from the top of cylinder B, and negative pressure electrode 7 is below ground electrode 6 and 50 mm away from ground electrode 6 in a vertical distance. Ground electrode 6 and negative pressure electrode 7 are connected to external DC negative pressure power supply 8 and ground wire 9 respectively through the power-on interface on the side wall of cylinder B by a wire wrapped with an insulating layer. The voltage of the DC negative pressure power supply is -400 V. After the residual gas is introduced from the semiconductor process chamber 1 and the DC negative pressure power supply 8 is powered on, a uniform plasma can be generated near and between the negative pressure electrode 7 and ground electrode 6.
[0052] Another cylinder C is set below cylinder B. Cylinder C is connected to cylinder B with a flange. A collecting tank 11 is set on the side wall below the interface. The width is 20mm and the depth is 30mm. The inner diameter of cylinder C is 120mm, which is smaller than the inner diameter of cylinder B. The other end of cylinder C is connected to a vacuum pump 13 through an exhaust pipe 12. The purified residual gas is extracted through the vacuum pump outlet.
[0053] During operation, the DC negative pressure power supply 8 is turned on, and a uniform plasma is generated between the ground electrode 6 and the negative pressure electrode 7. The residual gas and particulate matter flowing out of the semiconductor process chamber 1 enter the cylinder A. After condensation, the particulate matter 2 further grows and increases. When passing through the plasma between the ground electrode 6 and the negative pressure electrode 7, a large amount of charge will be adsorbed. Since the movement speed of electrons is greater than the movement speed of ions, when the charge of the particulate matter reaches stability, it will carry negative charge. When passing through the ground electrode 6, the negatively charged particulate matter will be repelled by the negative potential spherical crown metal orifice plate, move to the side wall of the cylinder B, and then fall into the collection tank 11 of the cylinder C, while the residual gas will not be affected when passing through the ground electrode 6 and the negative pressure electrode 7.
[0054] For the collection of residual gas particles, the contact electrode 6 and the negative pressure electrode 7 of the spherical metal orifice plate play a vital role. Therefore, the size parameter selection of the metal orifice plate needs to be strictly controlled. First, the metal orifice plate should not be too thick to reduce the weight and facilitate forging; second, the height of the metal orifice plate should not be too low and should be wide enough to ensure that the dust particles have enough time to move to the side wall of the cylinder B; finally, the aperture of the metal hole should not be greater than 7mm to ensure that the particles will not be washed through the orifice plate by the residual gas flow. After many tests, we found that the removal effect of residual gas particles is best when the thickness of the metal orifice plate is 0.5mm and the grid radius is 3mm.
[0055] For the particles falling into the collection tank 11, the cylinder C needs to be opened regularly for cleaning. The frequency of cleaning depends on the usage time. If there are too many particles in the collection tank, the collection tank will become shallow and unable to collect particles, thus reducing the purification efficiency. If a certain amount of adsorbent is added to the collection tank, the particles falling into the collection tank can be prevented from being blown out again by the airflow, which can improve the purification efficiency.
[0056] In this embodiment, the collection efficiency is tested by taking the continuous addition of pine pollen particles. In the experiment, the air pressure of the system is maintained at 80 Pa, and 5.682 grams of pine pollen particles with an average particle size of about 40 microns are evenly and slowly sprinkled into the cylinder A. Most of these particles are effectively collected by the method and enter the collection tank 11. After the experiment, the particles in the collection tank 11 are measured to be 5.636 grams, and the collection efficiency is 99.2%.
[0057] The present invention uses a plasma environment to charge the residual gas particles in semiconductor manufacturing, and then achieves the purpose of purifying the residual gas by controlling the movement of the residual gas particles. The equipment used in the present invention is simple and reusable, low-cost, energy-saving and environmentally friendly, can be flexibly installed in the tail gas treatment process, has high purification efficiency, and is of great significance to industrial production and environmental protection.
[0058] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
[0059] It will be apparent to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above, and that the present application can be implemented in other specific forms without departing from the spirit or essential features of the present application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present application. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.
Claims
1. A DC dust removal device for the front stage of a vacuum pump in a semiconductor process flow, characterized in that: It includes a condensation module, an electrostatic repulsion module and a collection module; the condensation module, the electrostatic repulsion module and the collection module are vertically arranged in sequence on the exhaust pipe between the vacuum chamber and the vacuum pump; the bottom of the collection module has a collection tank and an exhaust port; wherein, The condensation module is used to cool the exhaust gas discharged from the vacuum chamber, and promote the condensation and growth of particles in the exhaust gas into particles, which then enter the electrostatic repulsion module; The electrostatic repulsion module is used to form a free charge distribution area and an electrostatic field by using the generated plasma, so that the particulate matter in the exhaust gas is charged when the input exhaust gas flows through the free charge distribution area, and then the charged particulate matter is repelled and guided to move into the collection tank of the collection module by using the electrostatic field; The exhaust port of the collection module is connected to the vacuum pump through an exhaust pipe, so as to discharge the residual gas after the particulate matter is filtered out through the vacuum pump; Wherein, the electrostatic repulsion module comprises a cylinder B, in which a first spherical crown-shaped metal orifice plate and a second spherical crown-shaped metal orifice plate are arranged; wherein the first spherical crown-shaped metal orifice plate serves as a negative electrode, the second spherical crown-shaped metal orifice plate serves as a positive electrode, and the first spherical crown-shaped metal orifice plate is located below the second spherical crown-shaped metal orifice plate; the collection module comprises a cylinder C, the bottom edge of the inner wall of the cylinder C is provided with the collection groove, and the central area is the exhaust port; the tops of the first spherical crown-shaped metal orifice plate and the second spherical crown-shaped metal orifice plate face upward; the first spherical crown-shaped metal orifice plate is used to place The gas is electrically broken down to generate plasma to form a free charge distribution area, and the plasma is used to form a sheath electric field on the inner wall surface of the cylinder B, the surface of the first spherical crown metal hole plate and the surface of the second spherical crown metal hole plate, respectively. The sheath electric field on the surface of the first spherical crown metal hole plate and the second spherical crown metal hole plate is used to repel the charged particles and then slide toward the side wall of the cylinder B, and the sheath electric field on the surface of the cylinder B is used to repel the charged particles and then move them away from the inner wall surface of the cylinder B and slide into the collection tank of the collection module.
2. The DC dust removal device for the front stage of a vacuum pump in a semiconductor process flow according to claim 1, characterized in that: The aperture of the metal holes on the first spherical crown shaped metal hole plate is not greater than 7 mm, the thickness of the first spherical crown shaped metal hole plate is 0.5 mm, and the grid radius is 3 mm; the aperture of the metal holes on the second spherical crown shaped metal hole plate is not greater than 7 mm, the thickness of the second spherical crown shaped metal hole plate is 0.5 mm, and the grid radius is 3 mm.
3. The DC dust removal device for the front stage of a vacuum pump in a semiconductor process flow according to claim 1, characterized in that: The curvature of the second spherical cap-shaped metal hole plate is smaller than the curvature of the first spherical cap-shaped metal hole plate.
4. The DC dust removal device for the front stage of a vacuum pump in a semiconductor process flow according to claim 1, characterized in that: The inner diameter of the cylinder B is 160 mm, the outer diameter is 165 mm, and the length is 300 mm. The height of the second spherical crown metal perforated plate is 40 mm, and the height of the first spherical crown metal perforated plate is 60 mm and the maximum diameter is 120 mm. The second spherical crown metal perforated plate is 100 mm away from the top of the cylinder B, and the vertical distance between the first spherical crown metal perforated plate and the second spherical crown metal perforated plate is 50 mm.
5. The DC dust removal device for the front stage of a vacuum pump in a semiconductor process flow according to claim 4, characterized in that: The collection module includes a cylinder C, the bottom of which is provided with a collection groove and an exhaust port; the width of the collection groove is 20 mm and the depth is 30 mm; the inner diameter of the cylinder C is smaller than the inner diameter of the cylinder B.
6. The DC dust removal device for the front stage of a vacuum pump in a semiconductor process flow according to claim 1, characterized in that: The first spherical crown metal hole plate is electrically connected to the power supply system outside the cylinder B through the interface on the side wall of the cylinder B, and the second spherical crown metal hole plate is grounded through the interface on the side wall of the cylinder B.
7. The DC dust removal device for the front stage of a vacuum pump in a semiconductor process flow according to claim 6, characterized in that: The power supply system outside the cylinder B is a DC negative pressure power supply.
8. The DC dust removal device for the front stage of a vacuum pump in a semiconductor process flow according to claim 1, characterized in that: The condensation module includes a cylinder A and a water cooling pipe, the upper end of the cylinder A is connected to the exhaust gas outlet of the vacuum chamber, and the lower end of the cylinder A is connected to the electrostatic repulsion module; the water cooling pipe is wound around the outer wall of the cylinder A to cool the exhaust gas.