A gas circulation system suitable for MOCVD equipment

Abstract

The application discloses a kind of gas circulation systems suitable for MOCVD equipment, comprising: gas supply pipeline, gas recovery pipeline, gas storage tank, gas supplement pipeline and circulating cavity;The feeding cavity of MOCVD equipment is sealed in circulating cavity, and feeding and discharging operation are carried out in circulating cavity, and circulating cavity is isolated from atmosphere;The input end of gas supply pipeline is communicated with the gas path system of MOCVD equipment itself, and the output end provides purge gas to conveying cavity, feeding cavity, circulating cavity and transition cavity respectively;The input end of gas recovery pipeline is communicated with each chamber respectively, and the output end is communicated with gas storage tank, to realize that purge gas is recovered to gas storage tank;The sweep gas output by gas storage tank flows through gas detection component, and then circulates to each chamber through gas supplement pipeline respectively.The application has the advantages of compact structure, simple operation and low gas consumption, improves the cleanliness when wafer is fed and discharged, and reduces production running cost.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor process equipment technology, and specifically relates to a gas circulation system suitable for MOCVD equipment. Background Technology

[0002] Currently, compound semiconductor epitaxial wafers such as SiC, GaAs, and GaN are basically commercially mass-produced using CVD technology. Typically, the substrate is placed in a graphite chamber, the reaction chamber is heated to the temperature required for material growth, and various source gases required for growth are ejected from the gas inlet and undergo pyrolysis, reaction, and deposition on the substrate surface under specific temperature and pressure to form the corresponding epitaxial thin film.

[0003] Currently, most CVD epitaxial furnaces used in compound semiconductors still require operators to manually place wafers into wafer trays using suction pens. Each chamber needs to be continuously purged with large amounts of high-purity gas to maintain the cleanliness of the wafer surface. This method has the following main drawbacks:

[0004] 1. When loading and unloading wafers, the wafers are exposed to the atmosphere, and particles in the air can easily deposit on the wafer surface, resulting in unqualified final epitaxial quality;

[0005] 2. The airflow pattern at the loading and unloading points is not conducive to cleanliness control;

[0006] 3. Each chamber requires a large amount of high-purity gas, which is directly discharged after passing through the chamber, resulting in high equipment operating costs. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to address the problems of low wafer cleanliness, unstable epitaxial quality and high consumption of high-purity gas in existing CVD epitaxial furnaces. The invention provides a gas circulation system that is compact, easy to operate, highly clean, low in consumption and widely applicable to MOCVD equipment.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] A gas circulation system suitable for MOCVD equipment includes: a gas supply pipeline, a gas recovery pipeline, a gas storage tank, a gas replenishment pipeline, and a circulation chamber; the loading chamber of the MOCVD equipment is sealed inside the circulation chamber, and loading and unloading operations are all carried out inside the circulation chamber, which is isolated from the atmosphere;

[0010] The input end of the gas supply pipeline is connected to the gas system of the MOCVD equipment itself, and the output end of the gas supply pipeline provides purging gas to the conveying chamber, the feeding chamber, the circulation chamber, and the transition chamber respectively. The input end of the gas recovery pipeline is connected to the conveying chamber, the feeding chamber, the circulation chamber, and the transition chamber respectively, and the output end of the gas recovery pipeline is connected to the gas storage tank to realize the recovery of purging gas into the gas storage tank. The purging gas output from the gas storage tank flows through the gas detection component and then circulates to the conveying chamber, the feeding chamber, and the circulation chamber for purging through the gas replenishment pipeline respectively.

[0011] As a further improvement of the present invention, the circulation chamber is provided with a gas collection area, a gas filter, a feeding area, a gas perforated plate, and a gas collection area from top to bottom; a gas circulation pipeline is provided on the side of the circulation chamber, the input end of the gas circulation pipeline is connected to the gas collection area through a pipe with a first fan, and the output end of the gas circulation pipeline is connected to the gas collection area; in the circulation chamber, the purge gas is pushed from the gas collection area at the top through the gas filter to the feeding area to maintain the cleanliness of the feeding, and the particulate dust is carried to the gas collection area through the gas perforated plate. The particulate dust is initially deposited in the gas collection area to form a deposit layer. The gas then returns to the gas collection area through the gas circulation pipeline via the first fan. The gas filter filters the remaining particles and pushes them back to the feeding area to continue to maintain the cleanliness of the feeding, and so on.

[0012] As a further improvement of the present invention, the output end of the gas storage tank is connected to the main gas supply pipeline, and the main gas supply pipeline is provided with a first one-way valve, a second fan, an oxygen analyzer, a moisture analyzer and a tenth diaphragm valve in sequence; the moisture analyzer and the oxygen analyzer are used to detect the moisture content and oxygen content of the gas, respectively.

[0013] As a further improvement of the present invention, if the moisture analyzer and oxygen analyzer detect that the water and oxygen values ​​of the gas exceed the preset range, the gas supply from the storage tank is stopped, and the gas supply from the MOCVD equipment's own gas circuit system is activated. At the same time, the tenth diaphragm valve is opened to empty the gas in the storage tank and replenish the required supply gas.

[0014] As a further improvement of the present invention, the outlet of the gas storage tank is equipped with a pressure regulating device to adjust the outlet gas pressure to 30 ps i to 40 ps i; the gas replenishment pipeline includes a circulation chamber gas replenishment pipeline connected to the circulation chamber, a feeding chamber gas replenishment pipeline connected to the feeding chamber, a conveying chamber gas replenishment pipeline connected to the conveying chamber, and a transition chamber gas replenishment pipeline connected to the transition chamber. Gas flow controllers are provided on the circulation chamber gas replenishment pipeline, the feeding chamber gas replenishment pipeline, the conveying chamber gas replenishment pipeline, and the transition chamber gas replenishment pipeline to control the gas input of each gas replenishment pipeline respectively, thereby replacing the gas supply of the MOCVD equipment's own gas circuit system to purge each chamber.

[0015] As a further improvement of the present invention, a first filter, a second filter, a third filter and a fourth filter are respectively provided in the air supply pipeline of the circulation chamber, the air supply pipeline of the feeding chamber, the air supply pipeline of the conveying chamber and the air supply pipeline of the transition chamber, so as to realize that the circulating gas is filtered before entering each chamber for purging.

[0016] As a further improvement of the present invention, the pore size of the first filter, the second filter, the third filter and the fourth filter is all 0.003um.

[0017] As a further improvement of the present invention, the gas collection area can be independently disassembled and maintained to remove the accumulated layer.

[0018] As a further improvement of the present invention, a one-way valve is provided on the gas recovery pipeline to prevent the purge gas from flowing in reverse; diaphragm valves are provided on both the gas supply pipeline and the gas replenishment pipeline to control the pipeline opening and closing.

[0019] As a further improvement of the present invention, the gas in the gas path system of the MOCVD equipment is used to purge each chamber through the gas supply pipeline, and each chamber maintains a slight positive pressure of 0 to 2 mbar during the process. The overpressure part and the purged gas are transported to the gas storage tank for storage through the gas recovery pipeline.

[0020] Compared with the prior art, the advantages of the present invention are as follows:

[0021] The gas circulation system of this invention, applicable to MOCVD equipment, first stores the purging gas for each chamber in a gas storage tank. Then, the gas is detected and filtered through circulation and replenishment pipelines, and reused as purging gas to purge the chambers. Simultaneously, the loading and unloading chambers are sealed into independent circulation chambers. This top-down airflow circulation model—gas collection-filtration-collection-filtering-circulation-collection-re-filtration-purging—maintains the cleanliness of the loading and unloading areas. This gas circulation system provides a sealed and clean area for loading and unloading, improving the cleanliness of the wafer surface and the final epitaxial wafer quality. Furthermore, the system recycles the purging gas and monitors and controls the gas cleanliness and water / oxygen composition, reducing the equipment's reliance on high-purity gases and lowering operating costs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the structural principle of a gas circulation system applicable to an MOCVD equipment in a specific embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the circulation chamber and airflow circulation in a specific embodiment of the present invention.

[0024] Legend: 11. Air supply line to the conveying chamber; 12. Air supply line to the feeding chamber; 13. Air supply line to the circulation chamber; 14. Air supply line to the transition chamber; 21. Air return line to the conveying chamber; 22. Air return line to the feeding chamber; 23. Air return line to the circulation chamber; 24. Air return line to the transition chamber; 3. Main air supply line; 31. Air supply line to the circulation chamber; 32. Air supply line to the feeding chamber; 33. Air supply line to the conveying chamber; 34. Air supply line to the transition chamber; PV1~PV10, First diaphragm valve~Tenth diaphragm valve; CV1~CV5, First check valve~ 4. Moisture analyzer; 5. Oxygen analyzer; 61. First fan; 62. Second fan; 71-74. First flow controller to fourth flow controller; 81-84. First filter to fourth filter; 9. Gas storage tank; 101. Gas collection area; 102. Gas filter; 103. Feeding area; 104. Gas perforated plate; 105. Gas collection area; 106. Gas circulation pipeline; K. Stacking layer; 100. Conveying chamber; 200. Feeding chamber; 300. Circulation chamber; 400. Transition chamber. Detailed Implementation

[0025] 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.

[0026] Example

[0027] like Figure 1 and Figure 2 As shown, the gas circulation system of the present invention, applicable to MOCVD equipment, includes: a gas supply pipeline, a gas recovery pipeline, a gas storage tank 9, a gas replenishment pipeline, and a circulation chamber 300. The loading chamber 200 of the MOCVD equipment is sealed within the circulation chamber 300, and both loading and unloading operations are performed within the circulation chamber 300, which is isolated from the atmosphere.

[0028] The gas supply pipeline's inlet is connected to the MOCVD equipment's own gas system, and its outlet provides purge gas to the transfer chamber 100, loading chamber 200, circulation chamber 300, and transition chamber 400. The gas recovery pipeline's inlet is connected to the transfer chamber 100, loading chamber 200, circulation chamber 300, and transition chamber 400, and its outlet is connected to the gas storage tank 9, allowing the purge gas to be recovered into the storage tank 9. The purge gas output from the storage tank 9 flows through the gas detection component and then circulates through the gas replenishment pipeline back to the transfer chamber 100, loading chamber 200, and circulation chamber 300 for purging, thus achieving gas recycling within each chamber and reducing purge gas consumption. The capacity of the gas storage tank 9 can be selected according to the equipment's gas consumption requirements.

[0029] In this embodiment, the gas in the MOCVD equipment's own gas path system is used to purge each chamber through the gas supply pipeline, and each chamber maintains a slight positive pressure of 0 to 2 mbar during the process. The overpressure portion and the purged gas are transported to the gas storage tank 9 for storage through the gas recovery pipeline.

[0030] like Figure 2 As shown, in this embodiment, the circulation chamber 300 is provided with a gas collection area 101, a gas filter 102, a feeding area 103, a gas perforated plate 104, and a gas collection area 105 arranged sequentially from top to bottom. A gas circulation pipe 106 is provided on the side of the circulation chamber 300. The input end of the gas circulation pipe 106 is connected to the gas collection area 105 through a pipe with a first fan 61, and the output end of the gas circulation pipe 106 is connected to the gas collection area 101. Within the circulation chamber 300, purge gas is drawn from the gas collection area 101 at the top and pressed onto the feeding area 103 through the gas filter 102 to maintain the cleanliness of the feed. It also carries particulate dust through the gas perforated plate 104 to the gas collection area 105, where the particulate dust is initially deposited to form a deposit layer K. The gas then returns to the gas collection area 101 via the first blower 61 and the gas circulation pipeline 106. The gas filter 102 filters out the remaining particles and presses them back onto the feeding area 103 to continue maintaining the cleanliness of the feed. This cycle repeats continuously.

[0031] Furthermore, the gas collection area 105 can be independently disassembled and maintained to remove the accumulated layer K.

[0032] In this embodiment, the feeding area is independently sealed in the circulation chamber 300. The chamber contains a circulating airflow model that flows from top to bottom and back up. The dust is filtered in multiple stages along the way, which helps to control the cleanliness of the feeding area. At the same time, the particles are filtered step by step, which reduces the cost of gas use and can maintain the cleanliness of the gas for a long time.

[0033] like Figure 1 As shown, in this embodiment, the output end of the gas storage tank 9 is connected to the main gas supply pipeline 3. The main gas supply pipeline 3 is sequentially equipped with a first one-way valve CV1, a second fan 62, an oxygen analyzer 5, a moisture analyzer 4, and a tenth diaphragm valve PV10. The moisture analyzer 4 and the oxygen analyzer 5 are used to detect the moisture content and oxygen content of the gas, respectively.

[0034] In this embodiment, the gas supply pipeline is the gas supply pipeline for each chamber itself, while the gas recovery pipeline and gas replenishment pipeline are independent of the exhaust system of each chamber. Each chamber maintains its original exhaust system. If the moisture analyzer 4 and oxygen analyzer 5 detect that the water and oxygen values ​​of the gas exceed the preset range, the supply from the gas storage tank 9 is stopped, and the MOCVD equipment's own gas supply system is activated. At the same time, the tenth diaphragm valve PV10 is opened to empty the gas in the gas storage tank 9 and replenish the required supply gas. It can be understood that the water and oxygen values ​​of the gas can be set according to actual production needs.

[0035] In this embodiment, the outlet of the gas storage tank 9 is equipped with a pressure regulating device (not shown in the figure) to adjust the outlet gas pressure to 30 ps i to 40 ps i. The gas replenishment pipeline includes a circulation chamber replenishment pipeline 31 connecting to the circulation chamber 300, a feeding chamber replenishment pipeline 32 connecting to the feeding chamber 200, a conveying chamber replenishment pipeline 33 connecting to the conveying chamber 100, and a transition chamber replenishment pipeline 34 connecting to the transition chamber 400. A first flow controller 71, a second flow controller 72, a third flow controller 73, and a fourth flow controller 74 are respectively provided on the circulation chamber replenishment pipeline 31, the feeding chamber replenishment pipeline 32, the conveying chamber replenishment pipeline 33, and the transition chamber replenishment pipeline 34 to control the gas input of each replenishment pipeline, thereby replacing the gas supply of the MOCVD equipment's own gas circuit system to purge each chamber.

[0036] In this embodiment, the recovery, storage, reprocessing, and use of the purge gas are independent of the MOCVD equipment's own gas path system. When the stored gas meets the equipment's needs, it continuously circulates and purges, stopping the equipment's own gas supply to save operating costs. When the stored gas does not meet the requirements, the equipment's own gas system is automatically activated and the stored gas is updated, offering flexible configuration. The gas circulation system is independent of the equipment's own gas supply system, and the two systems can be flexibly switched, reducing equipment operating costs.

[0037] like Figure 1 As shown, in this embodiment, a first filter 81, a second filter 82, a third filter 83, and a fourth filter 84 are respectively provided on the air supply pipeline 31 of the circulation chamber, the air supply pipeline 32 of the feeding chamber, the air supply pipeline 33 of the conveying chamber, and the air supply pipeline 34 of the transition chamber, so as to realize that the circulating gas is filtered before entering each chamber for purging.

[0038] Furthermore, the pore size of the first filter 81, the second filter 82, the third filter 83, and the fourth filter 84 is all 0.003um.

[0039] like Figure 1As shown, in this embodiment, the gas recovery pipeline includes: a conveying chamber return gas pipeline 21 connecting to the conveying chamber 100, a feeding chamber return gas pipeline 22 connecting to the feeding chamber 200, a circulation chamber return gas pipeline 23 connecting to the circulation chamber 300, and a transition chamber return gas pipeline 24 connecting to the transition chamber 400. The conveying chamber return gas pipeline 21, the feeding chamber return gas pipeline 22, the circulation chamber return gas pipeline 23, and the transition chamber return gas pipeline 24 are respectively equipped with a fifth one-way valve CV5, a second one-way valve CV2, a third one-way valve CV3, and a fourth one-way valve CV4 to prevent the backflow of the purging gas and ensure the cleanliness of each chamber.

[0040] In this embodiment, the gas supply pipeline includes a conveying chamber gas supply pipeline 11 connecting to the conveying chamber 100, a feeding chamber gas supply pipeline 12 connecting to the feeding chamber 200, a circulation chamber gas supply pipeline 13 connecting to the circulation chamber 300, and a transition chamber gas supply pipeline 14 connecting to the transition chamber 400. A sixth diaphragm valve PV6, a seventh diaphragm valve PV7, and an eighth diaphragm valve PV7 are respectively installed on the conveying chamber gas supply pipeline 11, the feeding chamber gas supply pipeline 12, the circulation chamber gas supply pipeline 13, and the transition chamber gas supply pipeline 14. The first diaphragm valve 1 is installed on the gas supply line of the MOCVD equipment itself, and the fifth diaphragm valve PV5, the fourth diaphragm valve PV4, the third diaphragm valve PV3, and the ninth diaphragm valve PV9 are respectively installed on the gas supply line 31 of the circulation chamber, the gas supply line 32 of the feeding chamber, the gas supply line 33 of the conveying chamber, and the gas supply line 34 of the transition chamber. The diaphragm valves control the opening and closing of each line, and have the characteristics of simple structure, convenient installation, and precise control.

[0041] like Figure 2 As shown, the gas supplied by the gas supply line 13 and the gas replenishment line 31 of the circulation chamber first enters the gas circulation line 106, then enters the gas collection area 101 of the circulation chamber 300, and is pressed into the feeding area 103 through the gas filter 102, so as to ensure the cleanliness of the feeding to the greatest extent.

[0042] In this embodiment, the purging gas of each chamber is stored in appropriate amounts, and then reused for purging of each chamber after reasonable processing, testing and precise control. This minimizes the amount of high-purity gas used in the equipment. At the same time, the airflow model that recirculates from top to bottom and then back up has multi-stage filtration along the way, which extends the service life of the circulating gas as much as possible while strictly ensuring the cleanliness of the feeding area, improving the quality of the equipment's external processes and the performance of the final product. In addition, the gas circulation system and the equipment's own gas supply system coexist independently and can be flexibly switched. This significantly reduces the amount of high-purity gas used while ensuring equipment performance and lowering equipment operating costs.

[0043] 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 gas circulation system suitable for MOCVD equipment, characterized in that, include: Gas supply pipeline, gas recovery pipeline, gas storage tank (9), gas replenishment pipeline and circulation chamber (300); the loading chamber (200) of the MOCVD equipment is sealed in the circulation chamber (300), and the loading and unloading operations are all carried out in the circulation chamber (300), which is isolated from the atmosphere; The input end of the gas supply pipeline is connected to the gas system of the MOCVD equipment itself, and the output end of the gas supply pipeline provides purging gas to the transfer chamber (100), the loading chamber (200), the circulation chamber (300) and the transition chamber (400) respectively; the input end of the gas recovery pipeline is connected to the transfer chamber (100), the loading chamber (200), the circulation chamber (300) and the transition chamber (400) respectively, and the output end of the gas recovery pipeline is connected to the gas storage tank (9) to realize the recovery of purging gas into the gas storage tank (9); The circulation chamber (300) is provided with a gas collection area (101), a gas filter (102), a feeding area (103), a gas perforated plate (104), and a gas collection area (105) in sequence from top to bottom; a gas circulation pipeline (106) is provided on the side of the circulation chamber (300), the input end of the gas circulation pipeline (106) is connected to the gas collection area (105) through a pipe with a first fan (61), and the output end of the gas circulation pipeline (106) is connected to the gas collection area (101); In the circulation chamber (300), the purge gas is pushed from the gas collection area (101) at the top through the gas filter (102) to the feeding area (103) to maintain the cleanliness of the feeding and to carry particulate dust through the gas perforated plate (104) to the gas collection area (105). The particulate dust is initially deposited in the gas collection area (105) to form a deposit layer (K). The gas then passes through the first blower (61) through the gas circulation pipeline (106) back to the gas collection area (101). The gas filter (102) filters the remaining particles and pushes them back to the feeding area (103) to continue to maintain the cleanliness of the feeding. This cycle repeats continuously. The output end of the gas storage tank (9) is connected to the main gas supply pipeline (3). The main gas supply pipeline (3) is equipped with a first one-way valve (CV1), a second blower (62), an oxygen analyzer (5), a moisture analyzer (4), and a tenth diaphragm valve (PV10) in sequence. The moisture analyzer (4) and the oxygen analyzer (5) are used to detect the moisture content and oxygen content of the gas, respectively. The purging gas output from the gas storage tank (9) flows through the oxygen analyzer (5) and the moisture analyzer (4), and then circulates through the gas supply pipeline to the conveying chamber (100), the feeding chamber (200), and the circulation chamber (300) for purging. If the moisture analyzer (4) and oxygen analyzer (5) detect that the water and oxygen values ​​of the gas exceed the preset range, the gas storage tank (9) will be stopped and the MOCVD equipment's own gas supply system will be activated. At the same time, the tenth diaphragm valve (PV10) will be opened to empty the gas in the gas storage tank (9) and replenish the supply gas that meets the requirements. The gas in the MOCVD equipment's own gas path system is purged through the gas supply pipeline or the gas replenishment pipeline to each chamber, and each chamber maintains a slight positive pressure of 0 to 2 mbar during the process. The overpressure part and the purged gas are transported to the gas storage tank (9) through the gas recovery pipeline for storage.

2. The gas circulation system for MOCVD equipment according to claim 1, characterized in that, The outlet of the gas storage tank (9) is equipped with a pressure regulating device to adjust the outlet gas pressure to 30 psi to 40 psi; the gas replenishment pipeline includes a circulation chamber replenishment pipeline (31) connecting the circulation chamber (300), a feeding chamber replenishment pipeline (32) connecting the feeding chamber (200), a conveying chamber replenishment pipeline (33) connecting the conveying chamber (100), and a transition chamber replenishment pipeline (34) connecting the transition chamber (400). Gas flow controllers are provided on the circulation chamber replenishment pipeline (31), the feeding chamber replenishment pipeline (32), the conveying chamber replenishment pipeline (33), and the transition chamber replenishment pipeline (34) to control the gas input of each replenishment pipeline, thereby replacing the gas supply of the MOCVD equipment's own gas circuit system to purge each chamber.

3. The gas circulation system for MOCVD equipment according to claim 2, characterized in that, A first filter (81), a second filter (82), a third filter (83), and a fourth filter (84) are respectively provided on the gas supply line (31) of the circulation chamber, the gas supply line (32) of the feeding chamber, the gas supply line (33) of the conveying chamber, and the gas supply line (34) of the transition chamber, so as to realize that the circulating gas enters each chamber for purging after being filtered.

4. The gas circulation system for MOCVD equipment according to claim 3, characterized in that, The pore size of the first filter (81), the second filter (82), the third filter (83) and the fourth filter (84) is 0.003um.

5. The gas circulation system for MOCVD equipment according to any one of claims 1 to 4, characterized in that, The gas collection area (105) can be disassembled and maintained independently to remove the buildup (K).

6. The gas circulation system for MOCVD equipment according to any one of claims 1 to 4, characterized in that, The gas recovery pipeline is equipped with a one-way valve to prevent the purge gas from flowing backward; both the gas supply pipeline and the gas replenishment pipeline are equipped with diaphragm valves to control the pipeline opening and closing.

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