A particle trap for a mocvd apparatus

Abstract

The application discloses a kind of particle traps for MOCVD equipment, comprising: gas inlet flange, shell, mounting base, filter core assembly and gas outlet flange;Two ends of shell are connected gas inlet flange and gas outlet flange respectively, gas inlet flange is used to connect MOCVD equipment, and gas outlet flange is used to connect exhaust gas processor;Shell inside is equipped with mounting base, and mounting base divides into filter chamber and mixing chamber inside shell;Multiple filter core assemblies are installed side by side on mounting base, and filter core assembly is located in filter chamber, and the top of filter core assembly is sealed;The exhaust gas discharged by MOCVD equipment enters filter chamber inside by gas inlet flange, and enters filter core assembly inside by filter core assembly side portion after filtering, and then is discharged into mixing chamber by filter core assembly bottom portion, and finally filtered exhaust gas is discharged by gas outlet flange.The application has the advantages of compact structure, easy maintenance and uniform capture of small particles in process gas, solves the problem of too much sediment in pipeline caused by harsh environment of MOCVD equipment vacuum system due to particles, difficult to extract high vacuum, short maintenance cycle of butterfly valve sealing ring, short service life of dry pump and other problems.

Description

Technical Field

[0001] This invention relates to the field of metal-organic chemical vapor deposition (MOCVD) equipment technology, and more specifically to a particle trap for MOCVD equipment. Background Technology

[0002] MOCVD is a novel vapor-phase epitaxial growth technology developed based on vapor-phase epitaxy (VPE). MOCVD uses organic compounds of Group III and II elements and hydrides of Group V and VI elements as source materials for crystal growth. It performs vapor-phase epitaxy on a substrate via thermal decomposition reactions to grow various III-V main group and II-VI subgroup compound semiconductors, as well as thin single-crystal materials of their multi-component solid solutions. Common examples include second-generation semiconductor materials such as gallium arsenide (AsGa) and indium phosphide (InP), and third-generation semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN). Regardless of the material grown using MOCVD equipment, the equipment needs to operate under low pressure, high temperature, and carrier gas conditions, requiring a dry pump as a vacuum supply component and a butterfly valve as a pressure control system. However, byproducts in the MOCVD exhaust gas easily adhere to the exhaust pipes, causing problems such as large amounts of dust deposition, frequent maintenance of butterfly valve seals due to wear, and short lifespan of the dry pump.

[0003] In traditional particulate filters, due to the high temperature and corrosiveness of MOCVD process gases, stainless steel filters were often used. This method could only capture large particles and relied too heavily on the adsorption effect. Alternatively, a cold trap was used to cool the gas before capturing the particles. This method required a large space, and when the gas contained phosphorus impurities, a large amount of phosphorus easily accumulated in the cold trap, affecting the particle capture effect, and the filter maintenance cycle was extremely short. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a particle collector for MOCVD equipment that is compact in structure, easy to maintain and capable of uniformly capturing tiny particles in process gas.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A particulate filter for an MOCVD (Multi-Active Chemical Vapor Deposition) device includes: an inlet flange, a housing, a mounting base, filter elements, and an outlet flange. The housing is connected to the inlet flange and the outlet flange at its two ends, respectively. The inlet flange connects to the reactor of the MOCVD device, and the outlet flange connects to an exhaust gas processor. The mounting base inside the housing divides the interior into a filtration chamber and a mixing chamber. The filtration chamber communicates with the inlet flange, and the mixing chamber communicates with the outlet flange. Multiple filter elements are mounted side-by-side on the mounting base. The filter elements are located within the filtration chamber, and their tops are sealed. Exhaust gas from the MOCVD device enters the filtration chamber through the inlet flange, passes through the side of the filter elements for filtration, and then exits through the bottom of the filter elements into the mixing chamber. The filtered exhaust gas is finally discharged to the exhaust gas processor through the outlet flange.

[0007] As a further improvement of the present invention, the filter element assembly includes: a screw, a filter cloth, a filter screen, an upper cover plate, and a lower cover plate. The upper cover plate and the lower cover plate are connected and fixed on the mounting base by the screw. Both ends of the filter cloth and the filter screen are respectively attached to the upper cover plate and the lower cover plate. The filter screen is nested inside the filter cloth, and the screw is nested inside the filter screen. Gas flow channels exist between the filter screen and the filter cloth, and between the screw and the filter screen. The exhaust gas discharged from the MOCVD equipment enters the filter chamber through the inlet flange, then passes through the filter cloth and the filter screen in sequence, enters the gas flow channel between the filter screen and the screw, gathers in the mixing chamber, and finally exits from the outlet flange.

[0008] As a further improvement of the present invention, the mounting base is provided with multiple base holes, the lower cover plate is provided with a step and an air outlet, the step matches the base holes to fix the lower cover plate on the mounting base, and the air outlet matches the filter screen to allow the gas entering the filter screen to be collected into the mixing chamber through the air outlet; the upper cover plate is provided with a reserved hole, the bottom of the screw is connected and fixed to the air outlet flange by a nut, the top of the screw passes through the air outlet, the filter screen and the reserved hole in sequence, and the top of the screw is connected and fixed to the upper cover plate by a nut.

[0009] As a further improvement of the present invention, multiple layers of filter cloth are nested between the upper cover plate and the lower cover plate, and gas flow channels exist between adjacent layers of filter cloth.

[0010] As a further improvement of the present invention, the filter cloth is made of glass fiber material, and the particle size of the filtered particles can be selected in the range of 10 to 100 μm, and more preferably in the range of 30 to 40 μm.

[0011] As a further improvement of the present invention, the filter screen is a porous stainless steel hollow cylinder with a pore diameter of 2-4 mm.

[0012] As a further improvement of the present invention, dovetail grooves are provided on both the inlet flange and the outlet flange, and sealing rings are provided in the dovetail grooves to achieve sealed connection between the two ends of the housing and the inlet flange and the outlet flange, respectively.

[0013] As a further improvement of the present invention, the volume ratio of the filter chamber to the mixing chamber is 3:1.

[0014] As a further improvement of the present invention, the top of the air intake flange is provided with a handle.

[0015] As a further improvement of the present invention, the particulate trap is placed in the vacuum system of the MOCVD equipment. A first pneumatic ball valve and a first manual ball valve are sequentially provided between the reactor of the MOCVD equipment and the particulate trap. A second manual ball valve, a third manual ball valve, a butterfly valve, a second pneumatic ball valve and a dry vacuum pump are sequentially provided between the particulate trap and the exhaust gas processor. The input end and the output end of the particulate trap are respectively connected to a differential pressure gauge.

[0016] The butterfly valve works in conjunction with the diaphragm gauge that measures the reactor pressure to form an electronic pressure controller. Under process conditions, all the above valves are open, and only the butterfly valve plate continuously changes its opening degree, so that the reactor pressure is maintained at 50-100 mbar.

[0017] The dry vacuum pump serves as the source of low vacuum in the vacuum system; the differential pressure gauge reads the pressure difference before and after the particle collector, and the system sets a cleaning warning for the particle collector.

[0018] Compared with the prior art, the advantages of the present invention are as follows:

[0019] The particulate filter for MOCVD equipment of the present invention comprises an inlet flange, a housing, a mounting base, a filter element assembly, and an outlet flange, forming the main structure of the particulate filter. Specifically, the inlet flange and the outlet flange are respectively connected to both ends of the housing. The inlet flange is used to connect to the reactor of the MOCVD equipment, and the outlet flange is used to connect to the exhaust gas processor, thus realizing the entry and exit of exhaust gas into and out of the particulate filter. The dual-flange design facilitates maintenance by cleaning or replacing the filter element. Meanwhile, the housing contains a mounting base, which divides the interior of the housing into sections. The system comprises a filter chamber and a mixing chamber. The filter chamber is connected to the inlet flange, and the mixing chamber is connected to the outlet flange. This dual-chamber design allows for easy modification of the connection interfaces to better adapt to the installation space of the vacuum system. Furthermore, multiple filter element assemblies are installed side by side on the mounting base. The filter element assemblies are located within the filter chamber, and their tops are sealed. This means that exhaust gas entering the filter chamber can only enter the filter element through the side of the filter element assembly. This helps to extend the movement path of the exhaust gas within the filter element, improves the uniformity of the exhaust gas passing through the filter element, and enhances the exhaust gas purification effect. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the cross-sectional structure of a particle trap used in an MOCVD equipment according to a specific embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the cross-sectional structure of the filter element assembly in a specific embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram of the vacuum principle of the MOCVD equipment in a specific embodiment of the present invention.

[0023] Legend: 1. Inlet flange; 2. Handle; 3. Sealing ring; 4. Housing; 41. Filter chamber; 42. Mixing chamber; 5. Mounting base; 51. Base hole; 6. Screw; 7. Filter cloth; 8. Filter screen; 81. Filter hole; 9. Top cover plate; 91. Reserved hole; 10. Bottom cover plate; 101. Step; 102. Outlet port; 11. Outlet flange; 12. First pneumatic ball valve; 13. First manual ball valve; 14. Particle trap; 15. Second manual ball valve; 16. Third manual ball valve; 17. Butterfly valve; 18. Second pneumatic ball valve; 19. Dry vacuum pump; 20. Differential pressure gauge. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0025] Example

[0026] like Figures 1 to 3 As shown, the particulate filter for MOCVD equipment of the present invention includes: an inlet flange 1, a housing 4, a mounting base 5, filter element assemblies, and an outlet flange 11. The inlet flange 1 and the outlet flange 11 are respectively connected to both ends of the housing 4. The inlet flange 1 is used to connect to the reactor of the MOCVD equipment, and the outlet flange 11 is used to connect to the exhaust gas processor. The mounting base 5 is provided inside the housing 4, dividing the interior of the housing 4 into a filter chamber 41 and a mixing chamber 42. The volume ratio of the filter chamber 41 to the mixing chamber 42 is 3:1, which is beneficial for increasing the gas filtration capacity. The filter chamber 41 communicates with the inlet flange 1, and the mixing chamber 42 communicates with the outlet flange 11. Multiple filter element assemblies are uniformly mounted on the mounting base 5. The filter element assemblies are located inside the filter chamber 41, and the tops of the filter element assemblies are sealed. The exhaust gas from the MOCVD equipment enters the filter chamber 41 through the inlet flange 1, and then passes through the side of the filter element assembly for filtration. Finally, it is discharged from the bottom of the filter element assembly into the mixing chamber 42. The filtered exhaust gas is then discharged to the exhaust gas processor through the outlet flange 11. Furthermore, a handle 2 is provided on the top of the inlet flange 1 for easy movement.

[0027] In this embodiment, the main structure of the particulate filter consists of an inlet flange 1, a housing 4, a mounting base 5, a filter element assembly, and an outlet flange 11. Specifically, the inlet flange 1 and the outlet flange 11 are connected to both ends of the housing 4, respectively. The inlet flange 1 is used to connect to the reactor of the MOCVD equipment, and the outlet flange 11 is used to connect to the exhaust gas processor, thus realizing the entry and exit of exhaust gas into and out of the particulate filter. The dual-flange design facilitates maintenance by cleaning or replacing the filter element. Meanwhile, the housing 4 has an internal mounting base 5, which divides the interior of the housing 4 into a filter chamber 41 and a mixing chamber 42. The filter chamber 41 is connected to the inlet flange 1, and the mixing chamber 42 is connected to the outlet flange 11. This dual-chamber design allows for easy modification of the connection interfaces to better adapt to the installation space of the vacuum system. Furthermore, multiple filter element assemblies are installed side by side on the mounting base 5. The filter element assemblies are located inside the filter chamber 41, and the top of the filter element assembly is sealed. That is, the exhaust gas entering the filter chamber 42 can only enter the filter element through the side of the filter element assembly. This helps to extend the movement path of the exhaust gas inside the filter element, improves the uniformity of the exhaust gas passing through the filter element, and enhances the exhaust gas purification effect.

[0028] like Figure 2 As shown, in this embodiment, the filter element assembly includes: a screw 6, a filter cloth 7, a filter screen 8, an upper cover plate 9, and a lower cover plate 10. The upper cover plate 9 and the lower cover plate 10 are connected and fixed to the mounting base 5 by the screw 6. Both ends of the filter cloth 7 and the filter screen 8 are respectively attached to the upper cover plate 9 and the lower cover plate 10. The filter screen 8 is nested inside the filter cloth 7, and the screw 6 is nested inside the filter screen 8. Gas flow channels exist between the filter screen 8 and the filter cloth 7, and between the screw 6 and the filter screen 8. The exhaust gas discharged from the MOCVD equipment enters the filter chamber 41 through the inlet flange 1, then passes through the filter cloth 7 and the filter screen 8 in sequence. After the filter cloth 7 and the filter screen 8 capture particles, the gas enters the gas flow channel between the filter screen 8 and the screw 6, gathers in the mixing chamber 42, and is finally discharged from the outlet flange 11.

[0029] In this embodiment, the mounting base 5 has multiple base holes 51 evenly distributed on it, and the lower cover plate 10 has a step 101 and an air outlet 102. The step 101 matches the base holes 51 to fix the lower cover plate 10 on the mounting base 5. The air outlet 102 matches the filter screen 8, and the diameter of the air outlet 102 is slightly smaller than the diameter of the filter screen 8 so that the gas entering the filter screen 8 is collected into the mixing chamber 42 through the air outlet 102. The upper cover plate 9 has a reserved hole 91. The bottom of the screw member 6 is connected and fixed to the air outlet flange 11 by a nut. The top of the screw member 6 passes through the air outlet 102, the filter screen 8 and the reserved hole 91 in sequence. The top of the screw member 6 is connected and fixed to the upper cover plate 9 by a nut.

[0030] Furthermore, multiple layers of filter cloth 7 are nested between the upper cover plate 9 and the lower cover plate 10, and gas flow channels exist between adjacent layers of filter cloth 7. The exhaust gas enters the filter screen 8 only after being filtered by the multiple layers of filter cloth 7.

[0031] In this embodiment, the filter cloth 7 is made of glass fiber material, and the particle size of the filtered particles is 10-100μm, more preferably 30-40μm. It has many advantages such as high filtration efficiency, low resistance, long service life, high temperature resistance, corrosion resistance, light weight, and high strength. The filter screen 8 is a porous stainless steel hollow cylinder, and the pore size of the filter holes 81 is 2-4mm. The appropriate filter cloth 7 and filter screen 8 can be selected according to process requirements to improve the particle capture effect. Both the upper cover plate 9 and the lower cover plate 10 are made of polytetrafluoroethylene. The upper cover plate 9 is a blind plate as a whole, with only the pre-reserved hole 91 for threaded insertion. The filter element assembly of this embodiment is resistant to high temperature and corrosion, and can well cope with the harsh process conditions of MOCVD process with high exhaust gas temperature, acidic by-products such as chloride ions, and a large number of particles.

[0032] like Figure 1 As shown, in this embodiment, both the inlet flange 1 and the outlet flange 11 are provided with dovetail grooves, and sealing rings 3 are provided in the dovetail grooves to achieve a sealed connection between both ends of the housing 4 and the inlet flange 1 and the outlet flange 11, respectively. The inlet flange 1 has a standard KF inlet port, and the outlet flange 11 has a standard KF / ISO outlet port. The housing 4 is made of corrosion-resistant stainless steel, and the inner surface is sandblasted, resulting in significant adsorption of deposits.

[0033] In this embodiment, by setting an inlet flange 1, a housing 4, a filter element assembly and an outlet flange 11 that are sequentially sealed and connected, two independent chambers are provided inside the housing 4, and multiple independent intermediate air gas channels are provided inside the filter element, which correspond one-to-one with the base holes 51 that divide the housing 4. The exhaust gas finally flows into the mixing chamber 42 and is discharged to the next level via the outlet flange 11.

[0034] like Figure 3 As shown, in this embodiment, the particulate trap 14 is placed in the vacuum system of the MOCVD equipment. A first pneumatic ball valve 12 and a first manual ball valve 13 are sequentially provided between the reactor of the MOCVD equipment and the particulate trap 14. A second manual ball valve 15, a third manual ball valve 16, a butterfly valve 17, a second pneumatic ball valve 18 and a dry vacuum pump 19 are sequentially provided between the particulate trap 14 and the exhaust gas processor. The input and output ends of the particulate trap 14 are respectively connected to a differential pressure gauge 20.

[0035] Butterfly valve 17 works in conjunction with a diaphragm gauge that measures reactor pressure to form an electronic pressure controller. Under normal process conditions, all the above valves are open, with only the valve plate of butterfly valve 17 continuously changing its opening to maintain the reactor pressure at 50–100 mbar, achieving a control accuracy of ±0.2 mbar.

[0036] The dry vacuum pump 19 serves as the source of low vacuum in the vacuum system. The differential pressure gauge 20 reads the pressure difference before and after the particle trap, and a cleaning warning is issued for the particle trap 14 based on the system setpoint. Preferably, the cleaning warning value is 60 mbar; a value higher than 60 mbar indicates that the particle trap 14 has captured a large number of particles, potentially causing blockage in the vacuum system, and requires cleaning.

[0037] In the vacuum system of this embodiment, the pneumatic ball valve serves as a reactor or dry pump isolation valve. Manual ball valves are installed before and after the particulate trap 14. When maintaining the particulate trap 14, after multiple purgings, the manual ball valve and the pneumatic ball valve are shut off. The particulate trap 14, along with the manual ball valve, can be removed from the vacuum system. After disassembly, tin foil is quickly wrapped around the connection of the ball valve to minimize the occurrence of hazards caused by various toxic, flammable, and explosive gases in the MOCVD process.

[0038] In this embodiment, when the particulate filter 14 needs to be cleaned, after it is disassembled from the vacuum system, a special cleaning device should be connected, the two ends should be sealed and connected to the water connector, the ball valve should be opened, and the particulate filter 14 should be washed with water. Only after the water washing can the filter element assembly and the housing be completely disassembled and cleaned.

[0039] The particle trap 14 of this embodiment is used in the vacuum system of a certain type of MOCVD equipment. It uses a dual-chamber, multi-filter structure and a cold trap-free design. It uses glass fiber as the filter paper material, polytetrafluoroethylene as the filter cover material, and porous stainless steel as the internal flow channel material of the filter element. It can effectively handle the post-process products of III and V compound semiconductors in MOCVD equipment, trapping particles in them. At the same time, it can cope with high temperature and strong acid gas environment, greatly improve the cleanliness of the exhaust gas pipeline in the vacuum system, extend the life of the butterfly valve seal ring, and extend the service life of the dry pump.

[0040] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the spirit and technical essence of the invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A particle collector for MOCVD equipment, characterized in that, include: The assembly comprises an inlet flange (1), a housing (4), a mounting base (5), filter elements, and an outlet flange (11). The housing (4) is connected to the inlet flange (1) and the outlet flange (11) at its two ends. The inlet flange (1) is used to connect to the reactor of the MOCVD equipment, and the outlet flange (11) is used to connect to the exhaust gas processor. The housing (4) is provided with a mounting base (5) inside. The mounting base (5) divides the inside of the housing (4) into a filter chamber (41) and a mixing chamber (42). The filter chamber (41) is connected to the inlet flange (1), and the mixing chamber (42) is connected to the outlet flange (11). Multiple filter elements are installed side by side on the mounting base (5). The filter elements are located in the filter chamber (41), and the top of the filter elements is sealed. The filter element assembly includes: a screw (6), a filter cloth (7), a filter screen (8), an upper cover plate (9), and a lower cover plate (10). The upper cover plate (9) and the lower cover plate (10) are connected and fixed to the mounting base (5) by the screw (6). The two ends of the filter cloth (7) and the filter screen (8) are respectively attached to the upper cover plate (9) and the lower cover plate (10). The filter screen (8) is nested inside the filter cloth (7), and the screw (6) is nested inside the filter screen (8). There are gas flow channels between the filter screen (8) and the filter cloth (7), and between the screw (6) and the filter screen (8). The exhaust gas discharged from the MOCVD equipment enters the filter chamber (41) through the inlet flange (1), then passes through the filter cloth (7) and the filter screen (8) in sequence, and enters the air gas flow channel between the filter screen (8) and the screw (6), and enters the mixing chamber (42). The gas is collected and finally discharged from the outlet flange (11); the mounting base (5) is provided with multiple base holes (51), the lower cover plate (10) is provided with a step (101) and an outlet hole (102), the step (101) matches the base hole (51) to realize the lower cover plate (10) is fixed on the mounting base (5), the outlet hole (102) matches the filter screen (8) to realize the gas entering the filter screen (8) is collected into the mixing chamber (42) through the outlet hole (102); the upper cover plate (9) is provided with a reserved hole (91), the bottom of the screw (6) is connected and fixed to the outlet flange (11) by a nut, the top of the screw (6) passes through the outlet hole (102), the filter screen (8) and the reserved hole (91) in sequence, and the top of the screw (6) is connected and fixed to the upper cover plate (9) by a nut; Multiple layers of filter cloth (7) are nested between the upper cover plate (9) and the lower cover plate (10), and gas flow channels exist between adjacent layers of filter cloth (7); The particulate trap is placed in the vacuum system of the MOCVD equipment. A first pneumatic ball valve (12) and a first manual ball valve (13) are arranged in sequence between the reactor of the MOCVD equipment and the particulate trap. A second manual ball valve (15), a third manual ball valve (16), a butterfly valve (17), a second pneumatic ball valve (18), and a dry vacuum pump (19) are arranged in sequence between the particulate trap and the exhaust gas processor. The input and output ends of the particulate trap are respectively connected to a differential pressure gauge (20). The butterfly valve (17) works in conjunction with the diaphragm gauge that measures the reactor pressure to form an electronic pressure controller. Under process conditions, all of the above valves are open, and only the valve plate of the butterfly valve (17) continuously changes its opening degree, so that the pressure of the reactor is maintained at 50-100 mbar.

2. The particle collector for MOCVD equipment according to claim 1, characterized in that, The filter cloth (7) is made of glass fiber material.

3. The particle collector for MOCVD equipment according to claim 1, characterized in that, The filter screen (8) is a porous stainless steel hollow cylinder.

4. The particle trap for MOCVD equipment according to any one of claims 1 to 3, characterized in that, Both the inlet flange (1) and the outlet flange (11) are provided with dovetail grooves, and sealing rings (3) are provided in the dovetail grooves to achieve a sealed connection between the two ends of the housing (4) and the inlet flange (1) and the outlet flange (11) respectively.

5. The particle trap for an MOCVD equipment according to any one of claims 1 to 3, characterized in that, The volume ratio of the filter chamber (41) to the mixing chamber (42) is 3:

1.

6. The particle trap for an MOCVD equipment according to any one of claims 1 to 3, characterized in that, The air intake flange (1) is provided with a handle (2) on top.

7. A particle trap for an MOCVD equipment according to any one of claims 1 to 3, characterized in that, The dry vacuum pump (19) serves as the source of low vacuum in the vacuum system; the pressure difference before and after the particle collector is read by the differential pressure gauge (20), and the particle collector is cleaned and warned by the system setting value.

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