An on-line plasma cleaning apparatus and method for an LPCVD apparatus

Abstract

The application discloses an LPCVD equipment online plasma cleaning device and a cleaning method. A heating furnace body of the device is coaxially nested outside a periphery of a quartz reaction furnace. A furnace mouth of the quartz reaction furnace is provided with a furnace mouth door plate and a furnace door. The furnace door is provided with an air inlet hole. A furnace tail door plate is provided with an air exhaust pipe. An electrode introduction socket connected with a radio frequency power supply assembly is arranged on the furnace mouth door plate. An electrode column and an ICP generator are arranged on the furnace door and are connected with each other. The ICP generator is arranged around the periphery of the air inlet end of a quartz tube. The air exhaust end of the quartz tube penetrates through the furnace door. The furnace door is closed. The electrode column is inserted into the electrode introduction socket. The ICP generator is connected with the radio frequency power supply assembly. The quartz tube extends into the quartz reaction furnace. Fluoride gas is introduced into the quartz tube. The radio frequency power supply assembly is turned on. Under the action of the ICP generator, the fluoride gas forms fluorine-containing plasma, so that the quartz reaction furnace is cleaned online. The application has the advantages of compact structure, convenient maintenance and high cleaning efficiency.

Description

Technical Field

[0001] This invention belongs to the field of dry cleaning technology for LPCVD equipment, specifically relating to an online plasma cleaning device and cleaning method for LPCVD equipment. Background Technology

[0002] In the process of preparing amorphous silicon using LPCVD, the significant difference in thermal expansion coefficients between the quartz tubes used in LPCVD tubular equipment and amorphous silicon makes the quartz tubes prone to breakage under thermal stress after a thick amorphous silicon film is deposited on their walls. This increases safety risks and necessitates periodic replacement of the quartz tubes, leading to higher replacement costs and consequently higher manufacturing costs for solar cells. Furthermore, current LPCVD equipment commonly employs multi-tube integration, with 5 or 6 tubes integrated into a single unit. Disassembling and reassembling the quartz tubes reduces equipment uptime and is difficult. Since the quartz tubes operate at high temperatures for extended periods, cooling is required for cleaning. The thermal stress difference between the amorphous silicon and quartz on the tube surface during this process can easily cause the quartz tube to fracture, posing another safety risk.

[0003] Current technologies primarily employ chemical solution cleaning for quartz tube cleaning, involving prolonged immersion in acidic or alkaline solutions to remove surface films or contaminants, followed by rinsing and drying. This method requires removing the quartz tube from the equipment, and the cleaning, rinsing, and drying processes are time-consuming and inefficient. Therefore, cleaning quartz tubes on LPCVD equipment is unsuitable for TOPCon solar cells. Currently, LPCVD equipment typically replaces quartz tubes directly after they reach the end of their lifespan, leading to a surge in demand and soaring prices, further increasing the manufacturing cost of TOPCon solar cells and resulting in significant waste.

[0004] Chinese patent [CN202320357616] discloses an LPCVD quartz tube cleaning device, comprising: a reaction chamber and furnace mouth flange and furnace tail flange respectively disposed at both ends of the reaction chamber; the furnace tail flange is provided with a suction pipe, an electrical inlet, and an air inlet. The electrical inlet is used to install an electrical inlet assembly, which is connected to a discharge device and a radio frequency component in the reaction chamber respectively. The air inlet is used to install an air inlet pipe, which is used to transport fluoride gas into the reaction chamber. Under the excitation of the discharge device, the fluoride gas is decomposed into fluoride ions. The fluoride ions react with the amorphous silicon layer on the inner wall of the reaction chamber to remove the amorphous silicon layer. The suction pipe is connected to a vacuum pump to remove waste gas from the reaction chamber. This technical solution uses a discharge device placed inside the quartz chamber to discharge, ionizing the fluoride gas into fluoride ions to achieve the purpose of cleaning the quartz tube. However, this method also requires disassembling and assembling the equipment. When cleaning is needed, the discharge device is placed in a quartz tube and electrode rods are installed. It uses capacitively coupled plasma discharge, which results in a lower plasma density, which may lead to a slower cleaning speed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an online plasma cleaning device and cleaning method for LPCVD equipment that is compact in structure, easy to maintain, has high cleaning efficiency and is conducive to improving equipment capacity.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] An online plasma cleaning device for LPCVD equipment includes: a heating furnace body, a furnace opening door plate, a quartz reactor, an electrode inlet socket, an electrode column, a quartz tube, a furnace door, an ICP generator, a furnace tail door plate, and an exhaust pipe. The heating furnace body is coaxially nested around the quartz reactor and is used to heat the quartz reactor to perform amorphous silicon thin film deposition within it. The furnace opening of the quartz reactor is equipped with a furnace opening door plate and a furnace door assembly. The furnace door assembly has an air inlet to allow process gas to be delivered into the quartz reactor. The furnace tail door plate has an exhaust pipe connected to a vacuum pump to discharge gas from the quartz reactor. The furnace opening door plate has an electrode inlet socket connected to an RF power supply assembly. The furnace door assembly has an electrode column and an ICP generator. One end of the electrode column is connected to the ICP generator. The ICP generator surrounds the outer periphery of the air inlet end of the quartz tube, and the exhaust end of the quartz tube passes through the furnace door assembly axially.

[0008] When the furnace door assembly is open, the electrode post and the electrode inlet socket are separated. When the furnace door assembly is closed, the electrode post is inserted into the electrode inlet socket to connect the ICP generator to the RF power supply assembly. The exhaust end of the quartz tube extends into the quartz reactor. By introducing fluoride gas into the quartz tube and turning on the RF power supply assembly, the fluoride gas forms a fluorine-containing plasma in the quartz tube under the action of the ICP generator and flows into the quartz reactor to react with the amorphous silicon on the inner wall of the quartz reactor, thereby achieving online cleaning of the quartz reactor.

[0009] As a further improvement of the present invention, the ICP generator includes an upper coil flange, an air inlet pipe, a copper coil, and a lower coil flange; multiple turns of copper coil are wound around the outer periphery of the air inlet end of the quartz tube along the length direction, and the two sides of the copper coil are fixed to the outer periphery of the quartz tube through the upper coil flange and the lower coil flange, respectively. The air inlet end of the quartz tube is connected to the air inlet pipe to realize the delivery of fluoride gas into the quartz tube.

[0010] As a further improvement of the present invention, the copper coil is a hollow coil, and both ends of the hollow coil are provided with water-cooling connectors. Cooling water is circulated inside the hollow coil through the water-cooling connectors to cool the copper coil.

[0011] As a further improvement of the present invention, the ICP generator further includes isolation strips and fastening nuts; multiple isolation strips are arranged between the upper coil flange and the lower coil flange along the length direction of the quartz tube, and the two ends of the isolation strips are respectively connected and fixed to the upper coil flange and the lower coil flange by fastening nuts.

[0012] As a further improvement of the present invention, the length of the heating furnace body is less than the length of the quartz reactor. Both ends of the heating furnace body are fitted with heat-insulating cotton rings and heat-insulating cotton supports between the furnace opening and the furnace tail of the quartz reactor, and are fixed by the furnace opening door panel and the furnace tail door panel.

[0013] As a further improvement of the present invention, the furnace door assembly includes a quartz furnace door and a stainless steel furnace door, wherein the quartz furnace door and the stainless steel furnace door are spliced ​​together by a pressure ring on the quartz furnace door, with the quartz furnace door inside and the stainless steel furnace door outside.

[0014] As a further improvement of the present invention, the furnace door assembly further includes a furnace door support base and multiple furnace door support rods, one end of which is connected and fixed to the stainless steel furnace door, and the other end of which is connected and fixed to the furnace door support base.

[0015] As a further improvement of the present invention, silicon carbide paddles are installed on the quartz furnace door and the stainless steel furnace door. The silicon carbide paddles are used to carry the quartz boat so as to realize the entry and exit of the quartz boat into the quartz reactor. The paddle box of the silicon carbide paddle is connected to the furnace door support seat, and the furnace door support seat is connected to the boat pushing mechanism. The boat pushing mechanism is used to control the advance and retreat of the silicon carbide paddle and the furnace door assembly, thereby controlling the entry and exit of the quartz boat and the opening and closing of the furnace mouth.

[0016] As a further improvement of the present invention, the furnace tail door plate is also provided with a gas supply pipe and an internal thermocouple; the gas supply pipe is used to supply process gas into the quartz reactor, and the internal thermocouple is used to monitor the temperature inside the quartz reactor.

[0017] As a general technical concept, the present invention also provides a cleaning method based on the above-mentioned online plasma cleaning device for LPCVD equipment, comprising the following steps:

[0018] Step S1: When the thickness of amorphous silicon on the inner wall of the quartz reactor exceeds the preset value, the furnace door is closed using the boat pushing mechanism, and vacuuming is started through the evacuation pipe and vacuum pump.

[0019] Step S2: When the pressure inside the quartz tube is reduced to below 1 Pa, fluoride gas is introduced through the inlet pipe to maintain the pressure inside the quartz tube at 1 to 100 Pa.

[0020] Step S3: Apply radio frequency power to the copper coil of the ICP generator, wherein the power frequency is 13.56MHz and the power is 500~5000W;

[0021] Step S4: Under the action of the ICP generator, fluorine plasma and active free particles are generated in the quartz tube and remotely transmitted to the quartz reactor through a vacuum pump. The fluorine plasma and active free particles react chemically with the doped amorphous silicon thin film on the inner surface of the quartz reactor to form SiF4 and volatile byproducts.

[0022] Step S5: Extract the SiF4 and volatile byproducts formed in the quartz reactor using a vacuum pump;

[0023] Step S6: Keep the radio frequency power supply at the preset power for 60 to 300 minutes to ensure that the amorphous silicon on the inner wall of the quartz reactor is completely cleaned.

[0024] Step S7: After cleaning is complete, turn off the RF power supply and stop the gas supply. After evacuating the vacuum, fill the furnace with nitrogen to atmospheric pressure and open the furnace door to check the cleaning effect.

[0025] As a further improvement of the present invention, in step S2, the fluoride gas is a mixture of CF4 and O2, or a mixture of SF6 and Ar, or a mixture of NF3 and Ar, and the total gas flow rate is 100-5000 sccm; in step S3, the radio frequency power supply adopts a stepped power increase method.

[0026] Compared with the prior art, the advantages of the present invention are as follows:

[0027] 1. The online plasma cleaning device for LPCVD equipment of the present invention achieves uniform heating of the quartz reactor by coaxially nesting the heating furnace body around the quartz reactor. A furnace opening door plate and a furnace door assembly are provided at the furnace opening of the quartz reactor. The process gas is delivered to the quartz reactor through the air inlet on the furnace door assembly, and the gas is discharged from the quartz reactor by connecting the exhaust pipe on the furnace tail door plate to a vacuum pump. Simultaneously, the furnace opening door plate is provided with an electrode inlet socket connected to the radio frequency power supply assembly. The furnace door assembly is provided with interconnected electrode posts and an ICP generator. The ICP generator surrounds the outer circumference of the quartz tube's air inlet end, and the quartz tube's exhaust end passes through the furnace door assembly axially. When the furnace door assembly is open, the electrode posts and electrode inlet sockets are separated, and the ICP generator is not working. When the furnace door assembly is closed, the electrode posts are inserted into the electrode inlet sockets, thus achieving ICP cleaning. The CP generator is connected to the radio frequency power supply assembly. The exhaust end of the quartz tube extends into the quartz reactor. By introducing fluoride gas into the quartz tube and turning on the radio frequency power supply assembly, the fluoride gas forms fluorine-containing plasma in the quartz tube under the action of the CP generator and flows into the quartz reactor. The etchable fluorine plasma is evenly distributed throughout the quartz reactor and reacts with the amorphous silicon on the inner wall of the quartz reactor, realizing online cleaning of the quartz reactor.

[0028] 2. The cleaning method of this invention employs dry plasma cleaning technology. High-density, high-energy, active plasma containing fluorinated gases such as NF3, CF4, or SF6 is generated through inductively coupled plasma generation technology, and then introduced into a quartz reactor to react with the amorphous silicon or silicon oxide film on the furnace wall, producing volatile gaseous substances. This achieves rapid cleaning of the quartz reactor. Simultaneously, a quartz boat can be placed inside the reactor for cleaning, allowing cleaning of the quartz reactor without disassembling the quartz tubes, thereby extending the reactor's lifespan and reducing the cost of using TOPCon solar cells. Furthermore, after cleaning the quartz reactor, no additional treatment is required before amorphous silicon deposition, significantly improving cleaning efficiency and timeliness; high-concentration acid and alkali solutions are not needed, eliminating waste liquid treatment costs. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the main structural principle of the online plasma cleaning device for LPCVD equipment in a specific embodiment of the present invention.

[0030] Figure 2 This is a side view schematic diagram of the online plasma cleaning device for LPCVD equipment in a specific embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram of the main structure of the ICP generator in a specific embodiment of the present invention.

[0032] Figure 4 This is a side view schematic diagram of the ICP generator in a specific embodiment of the present invention.

[0033] Figure 5 This is a schematic diagram of the quartz reactor cleaning process in a specific embodiment of the present invention.

[0034] Legend: 1. Heating furnace body; 2. Furnace opening insulation cotton ring; 3. Furnace opening insulation cotton support; 4. Furnace opening door panel; 5. Quartz reactor; 6. Electrode inlet socket; 7. Electrode column; 8. Silicon carbide slurry; 9. Quartz tube; 10. Quartz furnace door; 11. Stainless steel furnace door; 12. Furnace door support rod; 13. ICP generator; 14. Furnace door support seat; 15. Push boat mechanism; 16. Furnace tail insulation cotton ring; 17. Furnace tail insulation cotton support; 18. Furnace tail door panel; 19. Ejector pipe; 20. Make-up pipe; 21. Internal thermocouple; 22. Insulation cotton baffle; 131. Upper coil flange; 132. Inlet pipe; 133. Water-cooled connector; 134. Copper coil; 135. Isolation strip; 136. Lower coil flange; 137. Fastening nut. Detailed Implementation

[0035] 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.

[0036] Example 1

[0037] like Figures 1 to 4As shown, the online plasma cleaning device for LPCVD equipment of the present invention includes: a heating furnace body 1, a furnace opening door plate 4, a quartz reactor 5, an electrode inlet socket 6, an electrode column 7, a quartz tube 9, a furnace door, an ICP generator 13, a furnace tail door plate 18, and an exhaust pipe 19. The heating furnace body 1 is coaxially nested around the quartz reactor 5 and is used to heat the quartz reactor 5 to realize the amorphous silicon thin film deposition process inside the quartz reactor 5. The furnace opening of the quartz reactor 5 is provided with a furnace opening door plate 4 and a furnace door assembly. The furnace door assembly is provided with an air inlet to realize the delivery of process gas into the quartz reactor 5. The furnace tail door plate 18 is provided with an exhaust pipe 19 connected to a vacuum pump to exhaust the gas inside the quartz reactor 5. The furnace door panel 4 is provided with an electrode inlet socket 6 connected to the radio frequency power supply assembly. The furnace door assembly is provided with an electrode post 7 and an ICP generator 13. One end of the electrode post 7 is connected to the ICP generator 13. The ICP generator 13 surrounds the outer periphery of the air inlet end of the quartz tube 9. The exhaust end of the quartz tube 9 passes through the furnace door assembly along the axial direction.

[0038] When the furnace door assembly is open, the electrode post 7 separates from the electrode inlet socket 6. When the furnace door assembly is closed, the electrode post 7 is inserted into the electrode inlet socket 6 to connect the ICP generator 13 to the RF power supply assembly. The exhaust end of the quartz tube 9 extends into the quartz reactor 5. By introducing fluoride gas into the quartz tube 9 and turning on the RF power supply assembly, under the action of the ICP generator 13, the fluoride gas forms a fluorine-containing plasma in the quartz tube 9 and flows into the quartz reactor 5, reacting with the amorphous silicon on the inner wall of the quartz reactor 5 to achieve online cleaning of the quartz reactor 5. In other words, the ICP generator 13 is integrated into the furnace door. LPCVD uses a closed-tube form for amorphous silicon deposition. During normal amorphous silicon processes, the ICP generator 13 does not operate. When cleaning of the quartz tube is required, the ICP generator 13 operates to generate plasma that is introduced into the quartz reactor 5 to complete the cleaning of the quartz reactor 5.

[0039] In this embodiment, uniform heating of the quartz reactor 5 is achieved by coaxially nesting the heating furnace body 1 around the quartz reactor 5. A furnace opening door plate 4 and a furnace door assembly are provided at the furnace opening of the quartz reactor 5. Process gas is delivered into the quartz reactor 5 via the air inlet on the furnace door assembly, and a vacuum pump is connected to the exhaust pipe 19 on the furnace tail door plate 18 to exhaust the gas from the quartz reactor 5. Simultaneously, the furnace opening door plate 4 is equipped with an electrode inlet socket 6 connected to the radio frequency power supply assembly. The furnace door assembly is equipped with interconnected electrode posts 7 and an ICP generator 13, with the ICP generator 13 surrounding the air inlet end of the quartz tube 9. The exhaust end of the quartz tube 9 passes through the furnace door assembly axially. When the furnace door assembly is open, the electrode posts 7 and the electrode inlet socket 6 separate, and the ICP generator 13 is not in operation. When the furnace door assembly is closed, the electrode post 7 is inserted into the electrode inlet socket 6, thus connecting the ICP generator 13 to the radio frequency power supply assembly. The exhaust end of the quartz tube 9 extends into the quartz reactor 5. By introducing fluoride gas into the quartz tube 9 and turning on the radio frequency power supply assembly, under the action of the ICP generator 13, the fluoride gas forms fluorine-containing plasma in the quartz tube 9 and flows into the quartz reactor 5. The etching fluorine plasma is evenly distributed throughout the quartz reactor 5 and reacts with the amorphous silicon on the inner wall of the quartz reactor 5, realizing online cleaning of the quartz reactor 5.

[0040] like Figure 3 and Figure 4 As shown, in this embodiment, the ICP generator 13 includes an upper coil flange 131, an air inlet pipe 132, a copper coil 134, and a lower coil flange 136. Multiple turns of copper coil 134 are wound around the outer periphery of the air inlet end of the quartz tube 9 along its length. The two sides of the copper coil 134 are fixed to the outer periphery of the quartz tube 9 via the upper coil flange 131 and the lower coil flange 136, respectively. The air inlet end of the quartz tube 9 is connected to the air inlet pipe 132 to facilitate the delivery of fluoride gas into the quartz tube 9.

[0041] Furthermore, the copper coil 134 is a hollow coil, and both ends of the hollow coil are provided with water-cooling connectors 133. Cooling water circulates inside the hollow coil through the water-cooling connectors 133 to cool the copper coil 134.

[0042] In this embodiment, the ICP generator 13 further includes isolation strips 135 and fastening nuts 137. Multiple isolation strips 135 are arranged along the length of the quartz tube 9 between the upper coil flange 131 and the lower coil flange 136, and the two ends of the isolation strips 135 are respectively connected and fixed to the upper coil flange 131 and the lower coil flange 136 by fastening nuts 137.

[0043] In this embodiment, the two ends of the copper coil 134 are connected by copper water-cooling connectors 133 for connecting cooling water and radio frequency power supply. The cooling water can maintain a very steep temperature gradient around the coil and discharge chamber, which is beneficial to extending the life of the coil and discharge chamber. Fluoride process gas is introduced into the quartz tube 9 through the inlet pipe 132. The function of the ICP generator 13 is to excite the fluoride process gas in the quartz tube 9 to form fluorine plasma when the amorphous silicon layer on the inner wall of the quartz reactor 5 is too thick and needs to be cleaned, so as to clean the inner wall of the quartz reactor 5. The operation of the ICP reactor 13 involves first evacuating the quartz tube 9, then introducing fluoride gases such as NF3, CF4, SF6, NF3 / Ar, CH4 / O2, or SF6 / Ar, or a mixture of fluorides with Ar and O2, through the inlet pipe 132. Cooling water is introduced through the water-cooling connector 133. After the gas pressure stabilizes, the radio frequency power supply is turned on. Under the action of the radio frequency power supply, the process gas inside the quartz tube 9 is ionized into fluorine plasma and fluorine-containing active free radicals, argon plasma, and oxygen plasma. Under the action of the vacuum pump, these plasmas and active free radicals are transported into the quartz reactor 5, where they react with the amorphous silicon layer on its inner wall to form volatile gases such as Si and F4, which are finally removed by the vacuum pump. After a period of cleaning, the amorphous silicon layer is completely reacted, and the inner wall of the quartz reactor 5 is cleaned.

[0044] like Figure 1 As shown, in this embodiment, the length of the heating furnace body 1 is less than the length of the quartz reactor 5. Insulating cotton rings and supports are fitted between both ends of the heating furnace body 1 and the furnace opening and tail of the quartz reactor 5, and are fixed by the furnace opening door panel 4 and the furnace tail door panel 18. Specifically, the heating furnace body 1 is cylindrical, filled with insulating material and evenly distributed heating wires, and wrapped with stainless steel. The portions of the heating furnace body 1 extending beyond the quartz reactor 5 are covered by furnace opening insulating cotton rings 2, furnace opening insulating cotton supports 3, furnace tail insulating cotton rings 16, and furnace tail insulating cotton supports 17, respectively, to reduce heat loss within the quartz reactor 5. These are then fixed by the furnace opening door panel 4 and the furnace tail door panel 18, and the furnace tail insulating cotton is reinforced by a furnace tail insulating cotton baffle 22.

[0045] In this embodiment, the furnace door assembly includes a quartz furnace door 10 and a stainless steel furnace door 11. The quartz furnace door 10 and the stainless steel furnace door 11 are spliced ​​together by a pressure ring on the quartz furnace door 10, with the quartz furnace door 10 inside and the stainless steel furnace door 11 outside, in order to reduce metal contamination inside the furnace body.

[0046] In this embodiment, the electrode post 7 and the ICP generator 13 are connected together and installed on the quartz furnace door 10 and the stainless steel furnace door 11. When the furnace door is open, the electrode post 7 and the electrode inlet socket 6 are separate. When the furnace door is closed, the electrode post 7 will be inserted into the electrode inlet socket 6, at which time power can be provided to the ICP generator 13.

[0047] Furthermore, the furnace door assembly also includes a furnace door support base 14 and multiple furnace door support rods 12. One end of the furnace door support rod 12 is connected and fixed to the stainless steel furnace door 11, and the other end of the furnace door support rod 12 is connected and fixed to the furnace door support base 14, which is used to provide structural support for the furnace door.

[0048] In this embodiment, silicon carbide paddles 8 are installed on the quartz furnace door 10 and the stainless steel furnace door 11. The silicon carbide paddles 8 are used to carry the quartz boat so that the quartz boat can enter and exit the quartz reactor 5. The paddle box of the silicon carbide paddle 8 is also connected to the furnace door support 14, and the furnace door support 14 is connected to the boat pushing mechanism 15. The boat pushing mechanism 15 is used to control the movement of the silicon carbide paddle 8 and the furnace door assembly, thereby controlling the entry and exit of the quartz boat and the opening and closing of the furnace opening.

[0049] like Figure 2 As shown, in this embodiment, the furnace tail door plate 18 is also equipped with a gas supply pipe 20 and an internal thermocouple 21. The gas supply pipe 20 is used to supply process gas into the quartz reactor 5, and the internal thermocouple 21 is used to monitor the temperature inside the quartz reactor 5 and control the process temperature during the deposition of amorphous silicon inside the quartz reactor 5.

[0050] In this embodiment, the exhaust pipe 19 at the furnace tail is connected to a vacuum pipe and a vacuum pump to provide a vacuum environment inside the quartz reactor 5. In addition to the gas inlet at the furnace opening, there is also a gas supply pipe 20 at the furnace tail to supply process gas during the LPCVD preparation of amorphous silicon. Gas supply at the furnace tail can improve the uniformity of thin film deposition.

[0051] In this embodiment, a quartz tube 9 is used as the plasma reaction chamber, which can extend into the quartz reactor 5. During the amorphous silicon thin film deposition process, the ICP generator 13 is not operational. Process gases such as silane are introduced through the furnace inlet and the furnace tail gas supply pipe to thermally decompose and form amorphous silicon. When the thickness of the amorphous silicon on the inner wall of the quartz reactor 5 reaches a relatively large thickness (>200 μm), online plasma cleaning of the quartz reactor 5 can be performed. The furnace door is closed, and fluoride gases such as NF3, CF4, SF6, NF3 / Ar, CH4 / O2, or SF6 / Ar, or a mixture of fluoride gases with Ar and O2, are introduced into the quartz tube 9. Then, the radio frequency power supply is turned on. Under the action of the ICP generator 13, the fluoride gas forms a fluorine-containing plasma in the quartz tube 9, which is then introduced into the quartz reactor 5 to react with the amorphous silicon on the inner wall of the furnace to form volatile gaseous products such as SiF4, thereby achieving the purpose of cleaning the quartz reactor 5.

[0052] Example 2

[0053] like Figure 5 As shown, the cleaning method of the present invention is implemented based on the online plasma cleaning device for LPCVD equipment in Example 1, and includes the following steps:

[0054] Step S1: When the thickness of amorphous silicon on the inner wall of quartz reactor 5 exceeds the preset value, for example, when the thickness of amorphous silicon exceeds 200μm, the furnace door is closed by using the boat pushing mechanism 15, and vacuuming is started through the evacuation pipe 19 and the vacuum pump.

[0055] Step S2: When the pressure inside the quartz tube 9 is reduced to below 1 Pa, fluoride gas is introduced through the air inlet pipe 132 to maintain the pressure inside the quartz tube 9 between 1 and 100 Pa.

[0056] Step S3: Apply radio frequency power to the copper coil 134 of the ICP generator 13, wherein the power frequency is 13.56MHz and the power is 500-5000W. The power can be preferably 500, 1000, 2000, 3000, or 5000W. To obtain a better cleaning effect, a stable plasma is required. Gradually or in stages increasing the power of the radio frequency power supply to the preferred power helps to generate stable and uniform plasma. Fluoride gas will ionize under the action of the radio frequency power supply to generate high-energy disordered fluorine plasma and argon plasma.

[0057] Step S4: Under the action of ICP generator 13, fluorine plasma and active free particles are generated in quartz tube 9 and remotely transmitted to quartz reactor 5 through vacuum pump. The fluorine plasma and active free particles react chemically with the doped amorphous silicon thin film on the inner surface of quartz reactor 5 to form SiF4 and volatile byproducts.

[0058] Step S5: Extract the SiF4 and volatile byproducts formed in the quartz reactor 5 using a vacuum pump;

[0059] Step S6: Maintain the RF power supply at the preset power for 60–300 minutes to ensure complete cleaning of the amorphous silicon on the inner wall of the quartz reactor 5. The specific discharge time depends on the thickness of the amorphous silicon film on the inner wall of the quartz reactor.

[0060] Step S7: After cleaning is complete, turn off the RF power supply and stop the gas supply. After evacuating the vacuum, fill the furnace with nitrogen to atmospheric pressure and open the furnace door to check the cleaning effect.

[0061] In step S2 of this embodiment, the fluoride gas is a mixture of CF4 and O2, and the total gas flow rate is 100-5000 sccm.

[0062] In other embodiments, the fluoride gas may also be a mixture of SF6 and Ar or a mixture of NF3 and Ar. Under the action of the ICP generator 13, argon plasma and fluorine plasma are generated inside the quartz tube 9. The high-energy ions generated by the argon and fluorine plasma bombard the inner surface of the quartz reactor 5, thereby accelerating the chemical reaction rate.

[0063] In this embodiment, dry plasma cleaning technology is employed. High-density, high-energy, active plasma containing fluorine, such as NF3, CF4, or SF6, is generated by ionization using inductively coupled plasma (ICP-P) technology. This plasma is then introduced into a quartz reactor to react with the amorphous silicon or silicon oxide film on the reactor wall, producing volatile gaseous substances. This achieves rapid cleaning of the quartz reactor. Simultaneously, a quartz boat can be placed inside the reactor for cleaning, allowing for cleaning without disassembling the quartz tubes. This extends the reactor's lifespan and reduces the cost of using TOPCon solar cells. Furthermore, after cleaning, amorphous silicon deposition can proceed directly without additional treatment, significantly improving cleaning efficiency and timeliness. High-concentration acid / alkali solutions are not required, eliminating waste liquid treatment costs.

[0064] 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. An online plasma cleaning device for LPCVD equipment, characterized in that, include: The furnace includes a heating furnace body (1), a furnace opening door plate (4), a quartz reactor (5), an electrode inlet socket (6), an electrode column (7), a quartz tube (9), a furnace door, an ICP generator (13), a furnace tail door plate (18), and an exhaust pipe (19). The heating furnace body (1) is coaxially nested around the quartz reactor (5) to heat the quartz reactor (5) for amorphous silicon thin film deposition. The furnace opening of the quartz reactor (5) is provided with a furnace opening door plate (4) and a furnace door assembly. The furnace door assembly is provided with an air inlet to allow process gas to enter. The gas is transported into the quartz reactor (5). The tail door plate (18) is provided with a suction pipe (19) connected to a vacuum pump for discharging the gas in the quartz reactor (5). The furnace opening door plate (4) is provided with an electrode inlet socket (6) connected to the radio frequency power supply assembly. The furnace door assembly is provided with an electrode post (7) and an ICP generator (13). One end of the electrode post (7) is connected to the ICP generator (13). The ICP generator (13) surrounds the outer periphery of the gas inlet end of the quartz tube (9). The exhaust end of the quartz tube (9) passes through the furnace door assembly along the axial direction. When the furnace door assembly is opened, the electrode post (7) and the electrode inlet socket (6) are separated from each other; when the furnace door assembly is closed, the electrode post (7) is inserted into the electrode inlet socket (6) to connect the ICP generator (13) with the radio frequency power supply assembly, and the exhaust end of the quartz tube (9) extends into the quartz reactor (5). By introducing fluoride gas into the quartz tube (9) and turning on the radio frequency power supply assembly, under the action of the ICP generator (13), the fluoride gas forms fluorine-containing plasma in the quartz tube (9) and flows into the quartz reactor (5) to react with the amorphous silicon on the inner wall of the quartz reactor (5) to achieve online cleaning of the quartz reactor (5).

2. The online plasma cleaning device for LPCVD equipment according to claim 1, characterized in that, The ICP generator (13) includes an upper coil flange (131), an air inlet pipe (132), a copper coil (134), and a lower coil flange (136). The outer periphery of the air inlet end of the quartz tube (9) is wound with multiple turns of copper coil (134) along the length direction, and the two sides of the copper coil (134) are fixed to the outer periphery of the quartz tube (9) through the upper coil flange (131) and the lower coil flange (136) respectively. The air inlet end of the quartz tube (9) is connected to the air inlet pipe (132) to realize the delivery of fluoride gas into the quartz tube (9).

3. The online plasma cleaning device for LPCVD equipment according to claim 2, characterized in that, The copper coil (134) is a hollow coil, and both ends of the hollow coil are provided with water-cooling connectors (133). Cooling water circulates in the hollow coil through the water-cooling connectors (133) to cool the copper coil (134).

4. The online plasma cleaning device for LPCVD equipment according to claim 3, characterized in that, The ICP generator (13) also includes isolation strips (135) and fastening nuts (137); multiple isolation strips (135) are arranged between the upper coil flange (131) and the lower coil flange (136) along the length of the quartz tube (9), and the two ends of the isolation strips (135) are respectively connected and fixed to the upper coil flange (131) and the lower coil flange (136) by fastening nuts (137).

5. The online plasma cleaning device for LPCVD equipment according to claim 3, characterized in that, The length of the heating furnace body (1) is less than the length of the quartz reactor (5). Both ends of the heating furnace body (1) are fitted with heat-insulating cotton rings and heat-insulating cotton supports between the furnace opening and the furnace tail of the quartz reactor (5), and are fixed by the furnace opening door panel (4) and the furnace tail door panel (18).

6. The online plasma cleaning device for LPCVD equipment according to claim 3, characterized in that, The furnace door assembly includes a quartz furnace door (10) and a stainless steel furnace door (11). The quartz furnace door (10) and the stainless steel furnace door (11) are spliced ​​together by a pressure ring on the quartz furnace door (10), with the quartz furnace door (10) inside and the stainless steel furnace door (11) outside.

7. The online plasma cleaning device for LPCVD equipment according to claim 6, characterized in that, The furnace door assembly also includes a furnace door support base (14) and multiple furnace door support rods (12). One end of the furnace door support rod (12) is connected and fixed to the stainless steel furnace door (11), and the other end of the furnace door support rod (12) is connected and fixed to the furnace door support base (14).

8. The online plasma cleaning device for LPCVD equipment according to claim 7, characterized in that, Silicon carbide paddles (8) are installed on the quartz furnace door (10) and the stainless steel furnace door (11). The silicon carbide paddles (8) are used to carry the quartz boat so that the quartz boat can enter and exit the quartz reactor (5). The paddle box of the silicon carbide paddles (8) is connected to the furnace door support seat (14), and the furnace door support seat (14) is connected to the boat pushing mechanism (15). The boat pushing mechanism (15) is used to control the advance and retreat of the silicon carbide paddles (8) and the furnace door assembly, thereby controlling the entry and exit of the quartz boat and the opening and closing of the furnace mouth.

9. The online plasma cleaning device for LPCVD equipment according to claim 3, characterized in that, The furnace tail door panel (18) is also provided with a gas supply pipe (20) and an internal thermocouple (21); the gas supply pipe (20) is used to supply process gas into the quartz reactor (5), and the internal thermocouple (21) is used to monitor the temperature inside the quartz reactor (5).

10. A cleaning method for an online plasma cleaning device for LPCVD equipment according to any one of claims 1 to 9, characterized in that, Includes the following steps: Step S1: When the thickness of amorphous silicon on the inner wall of the quartz reactor (5) exceeds the preset value, the furnace door is closed by using the pusher mechanism (15), and vacuuming is started through the evacuation pipe (19) and vacuum pump. Step S2: When the pressure inside the quartz tube (9) is reduced to below 1 Pa, fluoride gas is introduced through the air inlet pipe (132) to keep the pressure inside the quartz tube (9) between 1 and 100 Pa. Step S3: Apply radio frequency power to the copper coil (134) of the ICP generator (13), wherein the power frequency is 13.56MHz and the power is 500~5000W; Step S4: Under the action of the ICP generator (13), fluorine plasma and active free particles are generated in the quartz tube (9) and remotely transmitted to the quartz reactor (5) through a vacuum pump. The fluorine plasma and active free particles react chemically with the doped amorphous silicon thin film on the inner surface of the quartz reactor (5) to form SiF4 and volatile byproducts. Step S5: Extract the SiF4 and volatile byproducts formed in the quartz reactor (5) using a vacuum pump; Step S6: Keep the radio frequency power supply at the preset power for 60 to 300 minutes to ensure that the amorphous silicon on the inner wall of the quartz reactor (5) is completely cleaned. Step S7: After cleaning is complete, turn off the RF power supply and stop the gas supply. After evacuating the vacuum, fill the furnace with nitrogen to atmospheric pressure and open the furnace door to check the cleaning effect.

11. The cleaning method according to claim 10, characterized in that, In step S2, the fluoride gas is a mixture of CF4 and O2, or a mixture of SF6 and Ar, or a mixture of NF3 and Ar, with a total gas flow rate of 100–5000 sccm; in step S3, the radio frequency power supply adopts a stepped power increase method.

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