A method for repairing an empty run after maintenance of a tube PECVD apparatus

Abstract

The embodiment of the present application provides an empty running repair method after maintenance of a tubular PECVD device, wherein the empty running repair method comprises the following steps: after maintenance of the tubular PECVD device, placing an empty graphite boat in a furnace tube and depositing an aluminum oxide layer in the furnace tube; after depositing the aluminum oxide layer, depositing a silicon oxide layer on the aluminum oxide layer; after depositing the silicon oxide layer, depositing a multilayer silicon nitride layer on the silicon oxide layer step by step; after depositing the multilayer silicon nitride layer, controlling the furnace tube to cool down and then taking out the boat after back pressure. The empty running repair method provided by the present application realizes the increase of the thickness of the aluminum oxide and the silicon nitride, quickly repairs the damaged film of the furnace tube, and makes the tube reach the process environment before maintenance, so as to improve the problem that the tubular PECVD device for depositing aluminum oxide and SiNx to make a back passivation film layer is prone to have low first-boat efficiency and poor yield after maintenance.

Description

Technical Field

[0001] This invention relates to the field of crystalline silicon solar cell manufacturing technology, and in particular to a method for repairing tubular PECVD equipment after maintenance and idle running. Background Technology

[0002] Currently, due to the higher space requirements, the passivation of silicon wafers in solar cells is increasingly being achieved by using plasma-enhanced chemical vapor deposition (PECVD) of alumina and SiNx as the back passivation film.

[0003] However, during equipment maintenance, it is necessary to remove debris from the bottom of the furnace tube, which damages the alumina and silicon nitride film on the auxiliary heating element and the bottom wall of the furnace tube. This makes the combined furnace tube prone to low initial efficiency and poor yield after maintenance. To address the above issues, existing technology requires multiple saturation coating processes to restore the furnace tube to its pre-maintenance condition, which can significantly impact the actual output of the production line. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for restoring tubular PECVD equipment after maintenance, so as to solve the problem that existing tubular PECVD equipment used for depositing alumina and SiNx as back passivation film layers is prone to low first-ship efficiency and poor yield after maintenance.

[0005] To solve the above problems, the present invention is achieved through the following technical solution:

[0006] This invention proposes a method for restoring a tubular PECVD equipment after maintenance, comprising:

[0007] After maintenance of the tubular PECVD equipment, a graphite boat is placed in the furnace tube, and an alumina layer is deposited inside the furnace tube.

[0008] After depositing an alumina layer, a silicon oxide layer is deposited on the alumina layer;

[0009] A silicon oxide layer is deposited, and multiple silicon nitride layers are deposited stepwise on the aluminum oxide layer;

[0010] After depositing multiple layers of silicon nitride, the furnace tubes are cooled and pressurized before being unloaded from the boat.

[0011] Furthermore, in the aforementioned no-load repair method, depositing an alumina layer inside the furnace tube includes:

[0012] Under conditions of 280–350°C and 1500–2000 mTor inside the furnace tube, nitrous oxide with a flow rate of 7000–8000 sccm and trimethylaluminum gas with a flow rate of 80–120 g / h are introduced, and sputtering deposition is performed for 100–115 s to form the alumina layer inside the furnace tube.

[0013] Furthermore, in the aforementioned no-load repair method, during the deposition of the alumina layer inside the furnace tube, the radio frequency power supply discharge power is 5000-10000W, and the duty cycle is 20 / 1200.

[0014] Furthermore, in the aforementioned no-load repair method, depositing a silicon oxide layer on the alumina layer includes:

[0015] Under conditions of 400–500°C and 1000–1500 mTor inside the furnace tube, silane with a flow rate of 800–1500 sccm and nitrous oxide with a flow rate of 5000–10000 sccm are introduced, and sputtering deposition is performed for 80–150 s to form the silicon oxide layer on the alumina layer.

[0016] Furthermore, in the aforementioned no-load repair method, multiple silicon nitride layers are deposited stepwise on the silicon oxide layer, including:

[0017] Under the conditions of 400-500℃ and 1500-1800mTor in the furnace tube, silane with a flow rate of 2500-3000sccm and ammonia with a flow rate of 10000-10600sccm are introduced, and sputtering deposition is performed for 180-300s to form a first silicon nitride layer on the silicon oxide layer.

[0018] Under the conditions of 400-500℃ and 1500-1800mTor in the furnace tube, silane with a flow rate of 1500-2000sccm and ammonia with a flow rate of 10600-10900sccm are introduced, and sputtering deposition is performed for 180-300s to form a second silicon nitride layer on the first silicon nitride layer.

[0019] Under conditions of 400–500°C and 1500–1800 mTor inside the furnace tube, silane with a flow rate of 1000–1500 sccm and ammonia with a flow rate of 1100–1500 sccm are introduced, and sputtering deposition is performed for 180–300 s to form a third silicon nitride layer on the second silicon nitride layer.

[0020] Furthermore, in the aforementioned no-load repair method, after depositing the alumina layer and before depositing the silicon oxide layer on the alumina layer, the method further includes:

[0021] The alumina layer is then annealed.

[0022] Furthermore, in the aforementioned no-load repair method, the alumina layer undergoes annealing treatment, including:

[0023] Under conditions of 400–500℃ and 0mTor pressure inside the furnace tube, heat treatment is performed for 100–150 seconds.

[0024] After heat treatment, ammonia gas and nitrous oxide gas with a flow rate of 4000-6000 sccm are introduced into the furnace tube at a temperature of 400-500℃ and a pressure of 1200-1800 mTor, and the passivation reaction lasts for 200-500 seconds.

[0025] After the passivation reaction, the furnace tube is heated for 150–200 seconds at a temperature of 400–500℃ and a pressure of 0 mTor.

[0026] Furthermore, in the aforementioned no-load repair method, after depositing multiple layers of silicon nitride, the method further includes:

[0027] Perform protective gas cleaning on the furnace tubes.

[0028] Furthermore, in the aforementioned no-load repair method, the protective gas cleaning of the furnace tubes includes:

[0029] Nitrogen gas is introduced into the furnace tube at a flow rate of 15,000 to 25,000 sccm at 300 to 500°C, while the pressure inside the furnace tube is controlled at 0 mTor, and this is continued for 10 to 20 seconds.

[0030] Furthermore, in the aforementioned no-load repair method, before depositing an alumina layer inside the furnace tube, the method further includes:

[0031] The furnace tube is subjected to vacuum treatment.

[0032] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0033] In this embodiment of the invention, the provided method for no-load repair of a tubular PECVD equipment after maintenance involves placing an empty graphite boat in the furnace tube after maintenance, depositing an alumina layer inside the furnace tube, then depositing a silicon oxide layer on the alumina layer, followed by stepwise deposition of multiple silicon nitride layers on the alumina layer, and finally controlling the furnace tube to cool down and repressurize before unloading the boat. Through this no-load process, the thickness of the alumina and silicon nitride layers is increased, rapidly repairing the damaged film inside the furnace tube and restoring the pre-maintenance process environment within the tube. This improves upon the existing tubular PECVD equipment used for depositing alumina and SiNx as back-side passivation films, which often experiences low first-boat efficiency and poor yield after maintenance.

[0034] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0035] Figure 1 This is a flowchart of the no-load repair method for tubular PECVD equipment after maintenance, provided in an embodiment of the present invention. Detailed Implementation

[0036] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] This invention provides a method for restoring a tubular PECVD equipment after maintenance, such as... Figure 1 As shown, steps 101 to 104 are included:

[0038] Step 101: After maintenance of the tubular PECVD equipment, place an empty graphite boat in the furnace tube and deposit an alumina layer inside the furnace tube.

[0039] In step 101 above, an empty graphite boat is first placed into the furnace tube of the maintained tubular PECVD equipment. Then, plasma-enhanced chemical vapor deposition technology is used to form an alumina layer inside the furnace tube by sputtering with radio frequency power and introducing reactive gas, which can smooth out the inner wall of the furnace tube damaged by maintenance.

[0040] Optionally, before depositing the alumina layer inside the furnace tube, the furnace tube can be cleaned with a protective gas. This removes acidic gases carried by the graphite boat and graphite powder from the graphite boat sheets, ensuring cleanliness inside the tube. The protective gas is a stable gas that does not readily react with the graphite boat, such as nitrogen or an inert gas.

[0041] In practical applications, an empty graphite boat is a graphite boat that has been pre-cleaned.

[0042] Step 102: After depositing the alumina layer, deposit a silicon oxide layer on the alumina layer.

[0043] In step 102 above, after depositing the alumina layer, plasma-enhanced chemical vapor deposition technology is used to form a silicon oxide layer on the surface of the alumina layer by sputtering with radio frequency power and introducing reactive gas, thereby further smoothing the inner wall of the furnace tube damaged by maintenance.

[0044] Step 103: Deposit a silicon oxide layer, and then deposit multiple silicon nitride layers in stages on the silicon oxide layer.

[0045] In step 103 above, after depositing the silicon oxide layer, plasma-enhanced chemical vapor deposition technology is used. The radio frequency power supply is used for sputtering and the reaction gas is introduced. Through a stepwise approach, multiple silicon nitride layers are deposited in stages, so that the silicon nitride film formed is deposited more uniformly on the tube wall, further repairing the damaged film of the furnace tube.

[0046] Step 104: After depositing a multilayer silicon nitride layer, control the furnace tube to cool down and pressurize before unloading the boat.

[0047] In step 104 above, after the stepwise deposition of multiple silicon nitride layers, protective gases such as nitrogen are introduced to reduce the temperature inside the furnace tube to 390°C and restore the pressure to 10,000 millitor, thereby achieving the purpose of back pressure. Then, the furnace tube is controlled to exit the boat to complete the dry run process.

[0048] In practical applications, nitrogen gas at a flow rate of 50,000 sccm can be introduced for 100 seconds to achieve the aforementioned back pressure effect, and then the boat can be unloaded within 120 seconds.

[0049] In the no-load repair method for tubular PECVD equipment after maintenance provided in this embodiment of the invention, after maintenance of the tubular PECVD equipment, an empty graphite boat is placed in the furnace tube, and an alumina layer is deposited inside the furnace tube. Then, a silicon oxide layer is deposited on the alumina layer, followed by the stepwise deposition of multiple silicon nitride layers on the alumina layer. Finally, the furnace tube is cooled and pressure is controlled before the boat is unloaded. Through the above no-load process, the thickness of alumina and silicon nitride is increased, the damaged film in the furnace tube is quickly repaired, and the internal environment of the tube is restored to the state before maintenance. This improves the problem of low first-boat efficiency and poor yield that often occurs in existing tubular PECVD equipment used for depositing alumina and SiNx as back passivation films after maintenance.

[0050] Optionally, in one embodiment, after depositing an alumina layer inside the furnace tube, a leak detection operation is also required to check the overall airtightness of the furnace tube.

[0051] Optionally, in one embodiment, depositing an alumina layer inside the furnace tube includes:

[0052] Under conditions of 280–350°C and 1500–2000 mTor inside the furnace tube, nitrous oxide with a flow rate of 7000–8000 sccm and trimethylaluminum gas with a flow rate of 80–120 g / h are introduced, and sputtering deposition is performed for 100–115 s to form the alumina layer inside the furnace tube.

[0053] In this embodiment, under the conditions of a furnace tube temperature of 280-350°C and a pressure of 1500-2000 mTor, by increasing the flow rate of trimethylaluminum to 80-120 g / h and controlling the nitrous oxide flow rate to 7000-8000 sccm, the thickness of the formed alumina can be effectively increased, thereby quickly repairing the damaged film inside the tube.

[0054] Optionally, during the deposition of the alumina layer inside the furnace tube, the RF power supply discharge power is 5000–10000 W, and the duty cycle is 20 / 1200. By increasing the flow rate of trimethylaluminum, the deposition power, and the duty cycle, the furnace tube is fully saturated.

[0055] Optionally, in one specific embodiment, depositing an alumina layer inside the furnace tube includes: introducing nitrous oxide at a flow rate of 7000-8000 sccm and trimethylaluminum gas at a flow rate of 80-120 g / h under conditions of a furnace tube temperature of 300-310°C and a pressure of 1700 mTor; simultaneously controlling the foreboat RF power supply power to be 6300 W with a duty cycle of 20 / 1200, and controlling the foreboat RF power supply power to be 8300 W with a duty cycle of 20 / 1200; and sputtering deposition for 100-115 s to form the alumina layer inside the furnace tube. Through the above process, the alumina layer inside the furnace tube can be rapidly saturated.

[0056] Optionally, in one embodiment, the method further includes evacuating the furnace tube before depositing the alumina layer inside the furnace tube.

[0057] In this embodiment, the furnace tube is evacuated before the alumina layer is deposited to remove impurities such as water vapor and oxygen, thereby improving the purity of the alumina layer.

[0058] Optionally, in some embodiments, the vacuuming process for the furnace tube includes setting the temperature to 280–350°C, the time to 20 seconds, and the pressure to 0 millitor, that is, adjusting the pressure inside the furnace tube to 0 millitor within 20 seconds to complete the vacuuming operation.

[0059] Optionally, in some embodiments, after the vacuuming process is completed and before the alumina layer is deposited, the process further includes: introducing nitrous oxide at a flow rate of 7000-8000 sccm and trimethylaluminum gas at a flow rate of 80-120 g / h into the furnace tube at a temperature of 280-350°C, thereby adjusting the pressure inside the furnace tube to 1500-2000 mTor. This pressure adjustment of the furnace tube facilitates the subsequent rapid deposition of the alumina layer.

[0060] Optionally, in one embodiment, the method provided in this application, after depositing an alumina layer and before depositing a silicon oxide layer on the alumina layer, further includes:

[0061] The alumina layer is then annealed.

[0062] In this embodiment, the density of the alumina layer can be further improved by annealing the alumina layer.

[0063] Optionally, in one specific embodiment, the alumina layer is subjected to annealing treatment, including:

[0064] Under conditions of 400–500℃ and 0mTor pressure inside the furnace tube, heat treatment is performed for 100–150 seconds.

[0065] After heat treatment, ammonia gas and nitrous oxide gas with a flow rate of 4000-6000 sccm are introduced into the furnace tube at a temperature of 400-500℃ and a pressure of 1200-1800 mTor, and the passivation reaction lasts for 200-500 seconds.

[0066] After the passivation reaction, the furnace tube is heated for 150–200 seconds at a temperature of 400–500℃ and a pressure of 0 mTor.

[0067] In this specific embodiment, the annealing of the alumina layer is completed by heating, pressure regulation, hydrogen-oxygen passivation, and then heating again.

[0068] For example, the heating process includes: controlling the pressure to 0 millitor at a temperature of 445 to 460°C, turning on the auxiliary heating and controlling the auxiliary heating temperature to 480°C, and continuing for 120 seconds.

[0069] The pressure regulation process includes: introducing ammonia gas at a flow rate of 5000 sccm and nitrous oxide gas at a flow rate of 5500 sccm under the condition that the temperature inside the furnace tube is 445-460℃, and adjusting the pressure inside the furnace tube to 1500 mTor.

[0070] The hydrogen-oxygen passivation process includes: under the conditions of a furnace tube temperature of 445-460℃ and a pressure of 1500mTor, the auxiliary heating is turned on and the auxiliary heating temperature is controlled at 480℃, ammonia gas with a flow rate of 5000sccm and nitrous oxide with a flow rate of 5500sccm are introduced, and the power of the front boat RF power supply is controlled at 5000W and the duty cycle is 30 / 1500, and the sputtering deposition is carried out for 350s;

[0071] The reheating process includes: controlling the pressure to 0 millitor at a temperature of 445–460°C, turning on the auxiliary heating and controlling the auxiliary heating temperature to 480°C for 170 seconds.

[0072] Optionally, in one embodiment, depositing a silicon oxide layer on the alumina layer includes:

[0073] Under conditions of 400–500°C and 1000–1500 mTor inside the furnace tube, silane with a flow rate of 800–1500 sccm and nitrous oxide with a flow rate of 5000–10000 sccm are introduced, and sputtering deposition is performed for 80–150 s to form the silicon oxide layer on the alumina layer.

[0074] In this embodiment, by introducing silane at a flow rate of 800-1500 sccm and nitrous oxide at a flow rate of 5000-10000 sccm under conditions of 400-500°C and 1000-1500 mTor inside the furnace tube, a uniform silicon oxide layer can be rapidly formed.

[0075] Optionally, in one specific embodiment, depositing a silicon oxide layer on the alumina layer includes: introducing silane at a flow rate of 1000 sccm and nitrous oxide at a flow rate of 8500 sccm under conditions of 445–460°C and 1300 mTor pressure inside the furnace tube, while simultaneously controlling the foreboard RF power supply power to be 11000 W and the duty cycle to be 50 / 1200, and controlling the foreboard RF power supply power to be 13000 W and the duty cycle to be 50 / 1200, sputtering deposition for 40 s to form the silicon oxide layer inside the furnace tube. Through the above process, the silicon oxide layer inside the furnace tube can be rapidly saturated.

[0076] Optionally, in one embodiment, the method further includes evacuating the furnace tube before depositing the silicon oxide layer inside the furnace tube.

[0077] In this embodiment, the furnace tube is evacuated before the silicon oxide layer is deposited to remove residual nitrous oxide and other impurities, thereby improving the purity of the silicon oxide layer.

[0078] Optionally, in some embodiments, before depositing the silicon oxide layer inside the furnace tube, the furnace tube is evacuated, which includes setting the temperature to 400-500°C, the time to 15 seconds, and the pressure to 0 millitor, that is, adjusting the pressure inside the furnace tube to 0 millitor within 15 seconds to complete the evacuation process.

[0079] Optionally, in some embodiments, after the vacuuming process is completed and before the deposition of the silicon oxide layer, the process further includes: introducing silane at a flow rate of 800-1500 sccm and nitrous oxide at a flow rate of 5000-10000 sccm at a furnace tube temperature of 400-500°C, thereby adjusting the pressure inside the furnace tube to 1000-1500 mTor. This furnace tube pressure adjustment facilitates the subsequent rapid deposition of the silicon oxide layer.

[0080] Optionally, in one embodiment, a multilayer silicon nitride layer is deposited stepwise on the silicon oxide layer, including:

[0081] Under the conditions of 400-500℃ and 1500-1800mTor in the furnace tube, silane with a flow rate of 2500-3000sccm and ammonia with a flow rate of 10000-10600sccm are introduced, and sputtering deposition is performed for 180-300s to form a first silicon nitride layer on the silicon oxide layer.

[0082] Under the conditions of 400-500℃ and 1500-1800mTor in the furnace tube, silane with a flow rate of 1500-2000sccm and ammonia with a flow rate of 10600-10900sccm are introduced, and sputtering deposition is performed for 180-300s to form a second silicon nitride layer on the first silicon nitride layer.

[0083] Under conditions of 400–500°C and 1500–1800 mTor inside the furnace tube, silane with a flow rate of 1000–1500 sccm and ammonia with a flow rate of 1100–1500 sccm are introduced, and sputtering deposition is performed for 180–300 s to form a third silicon nitride layer on the second silicon nitride layer.

[0084] In this embodiment, by depositing three silicon nitride layers on the silicon oxide surface in a progressive manner, the silicon nitride film can be deposited more uniformly on the pipe wall.

[0085] Optionally, in some embodiments, the deposition process of the first silicon nitride layer is as follows:

[0086] Under conditions of 445–460℃ and 1700 mTor inside the furnace tube, silane with a flow rate of 2700 sccm and ammonia with a flow rate of 10500 sccm were introduced. At the same time, the power of the front boat RF power supply was controlled at 14500W and the duty cycle at 50 / 700, and the power of the front boat RF power supply was controlled at 17500W and the duty cycle at 50 / 700. Sputtering deposition lasted for 200 s.

[0087] Optionally, in some embodiments, the deposition process of the second silicon nitride layer is as follows:

[0088] Under conditions of 445–460℃ and 1700 mTor inside the furnace tube, silane with a flow rate of 1800 sccm and ammonia with a flow rate of 10725 sccm were introduced. At the same time, the power of the front boat RF power supply was controlled at 14500W and the duty cycle at 50 / 650, and the power of the front boat RF power supply was controlled at 17500W and the duty cycle at 50 / 650. Sputtering deposition lasted for 200 s.

[0089] Optionally, in some embodiments, the deposition process of the third silicon nitride layer is as follows:

[0090] Under conditions of 445–460℃ and 1700 mTor inside the furnace tube, silane with a flow rate of 1450 sccm and ammonia with a flow rate of 12800 sccm were introduced. At the same time, the power of the front boat RF power supply was controlled at 14500W and the duty cycle at 50 / 650, and the power of the front boat RF power supply was controlled at 17500W and the duty cycle at 50 / 650. Sputtering deposition lasted for 200 s.

[0091] Optionally, in some embodiments, after depositing the silicon oxide layer and before depositing the multilayer silicon nitride layer, the process further includes: introducing silane at a flow rate of 1000-1500 sccm and ammonia at a flow rate of 1100-1500 sccm into the furnace tube at a temperature of 400-500°C, thereby adjusting the pressure inside the furnace tube to 1500-1800 mTor. This pressure adjustment of the furnace tube facilitates the subsequent rapid deposition of the silicon nitride layer.

[0092] Optionally, in one embodiment, the method provided in this application, after depositing a multilayer silicon nitride layer, further includes:

[0093] Perform protective gas cleaning on the furnace tubes.

[0094] In this embodiment, protective gases such as nitrogen are introduced into the furnace tube to carry away the waste gas inside the tube, thereby achieving further cleaning of the furnace tube.

[0095] Optionally, in one specific embodiment, the protective gas purging of the furnace tubes includes:

[0096] Nitrogen gas is introduced into the furnace tube at a flow rate of 15,000 to 25,000 sccm at 300 to 400°C, while the pressure inside the furnace tube is controlled at 0 mTor, and this process is continued for 10 to 20 seconds.

[0097] In this specific embodiment, by lowering the temperature to 300-400°C, then introducing nitrogen gas at a flow rate of 15000-25000 sccm, and controlling the vacuum pump to maintain continuous operation at a pumping speed, the furnace tube is kept at 0 mTor, which can remove the waste gas inside the furnace tube and achieve further cleaning of the furnace tube.

[0098] Optionally, before cleaning the furnace tube with protective gas, the method provided in this application embodiment further includes: performing a vacuum treatment on the furnace tube.

[0099] In this embodiment, the furnace tube is evacuated before the protective gas cleaning to remove residual impurities such as silane, ammonia, and silicon nitride dust, so that the furnace tube can be further cleaned with protective gas in the future.

[0100] Optionally, in some embodiments, before cleaning the furnace tube with protective gas, the furnace tube is evacuated, which includes setting the temperature to 390°C, the time to 15 seconds, and the pressure to 0 millitor, that is, adjusting the pressure inside the furnace tube to 0 millitor within 15 seconds to complete the evacuation operation.

[0101] The present invention will be described in detail below through embodiments.

[0102] Example 1

[0103] (1) Open the furnace door: the time is 25-45s, the temperature is set to 300-310℃, the nitrogen flow rate is 20000sccm, and the pressure is 10000mTor;

[0104] (2) Boat entry: time is 125-140s, temperature is set to 300-310℃, and pressure is 10000 millitor;

[0105] (3) First step: vacuuming: time is 50s, temperature is set to 300~310℃, and pressure is 10000 mTortos;

[0106] (4) Second step: Vacuuming: Time set to 200s, temperature set to 300~310℃, pressure set to 0 mTorr;

[0107] (5) Leak detection: time is 60s, temperature is set to 300~310℃, and pressure is 10000 mTortos;

[0108] (6) Vacuuming: Time is 20s, temperature is set to 300~310℃, and pressure is 0 millitor;

[0109] (7) Pressure adjustment: time is 30s, temperature is set to 300~310℃, nitrous oxide flow rate is 7450sccm, TMA flow rate is 98g / h, and pressure is 1700mTortos;

[0110] (8) Alumina deposition: time is 100-115s, temperature is set to 300-310℃, nitrous oxide flow rate is 7450sccm, TMA flow rate is 98g / h, pressure is 1700mTor, front boat RF power discharge power is 6300W, duty cycle is 20 / 1200, rear boat RF power discharge power is 8300W, duty cycle is 20 / 1200;

[0111] (9) Vacuuming: Time is 30s, temperature is set to 445~460℃, and pressure is 0 millitor;

[0112] (10) First step of heating: time is 120s, temperature is set to 445~460℃, pressure is 0 mTorr, auxiliary heating is turned on and auxiliary heating temperature is set to 480℃.

[0113] (11) Pressure adjustment: time is 20s, temperature is set to 445~460℃, pressure is 1500 mTortos, ammonia flow rate is 5000 sccm, nitrous oxide flow rate is 5500 sccm;

[0114] (12) Hydrogen-oxygen passivation: time is 350s, temperature is set to 445~460℃, pressure is 1500 mTortos, ammonia flow rate is 5000 sccm, nitrous oxide flow rate is 5500 sccm, front boat RF power discharge power is 5000W, duty cycle is 30 / 1500, rear boat RF power discharge power is 5500W, duty cycle is 30 / 1500, auxiliary heating is turned on and auxiliary heating temperature is set to 480℃;

[0115] (13) Second step of heating: time 170s, temperature set to 445~460℃, pressure 0 mTorr, auxiliary heating turned on and auxiliary heating temperature set to 480℃.

[0116] (14) Vacuuming: Time is 15s, temperature is set to 445~460℃, and pressure is 0 millitor;

[0117] (15) Pressure adjustment: time is 15s, temperature is set to 445~460℃, pressure is 1300 mTorr, silane flow rate is 1000 sccm, nitrous oxide flow rate is 8500 sccm;

[0118] (16) Silica deposition: time is 40s, temperature is set to 445~460℃, pressure is 1300 mTortos, silane flow rate is 1000 sccm, nitrous oxide flow rate is 8500 sccm, front boat RF power discharge power is 11000W and duty cycle is 50 / 1000, rear boat power is 13000W and duty cycle is 50 / 1000;

[0119] (17) Pressure regulation: time is 15s, temperature is set to 445~460℃, pressure is 1700 mTorr, silane flow rate is 2700 sccm, ammonia flow rate is 10500 sccm.

[0120] (18) First layer silicon nitride deposition: time set to 200s, temperature set to 445~460℃, pressure set to 1700 mTortos, silane flow rate 2700 sccm, ammonia flow rate 10500 sccm, front boat RF power discharge power 14500W, duty cycle 50 / 700, rear boat power 17500W, duty cycle 50 / 650;

[0121] (19) Second layer silicon nitride deposition: time set to 200s, temperature set to 445~460℃, pressure set to 1700 mTortos, silane flow rate to 1800 sccm, ammonia flow rate to 10725 sccm, front boat RF power discharge power to 14500W, duty cycle to 50 / 650, rear boat RF power discharge power to 17500W, duty cycle to 50 / 650;

[0122] (20) Third layer silicon nitride deposition: time set to 200s, temperature set to 445~460℃, pressure set to 1700 mTorr, silane flow rate set to 1450 sccm, ammonia flow rate set to 12800 sccm, front boat RF power discharge power set to 14500W, duty cycle set to 50 / 650, rear boat RF power discharge power set to 17500W, duty cycle set to 50 / 650;

[0123] (21) Vacuuming: Time is 15s, temperature is set to 390℃, and pressure is 0 millitor;

[0124] (22) Cleaning: Time is 15s, temperature is set to 390℃, nitrogen flow rate is 20000sccm, and pressure is 0 millitor;

[0125] (23) Vacuuming: Time is 20s, temperature is set to 390℃, and pressure is 0 millitor;

[0126] (24) Back pressure: time sccm 100s, temperature set to 390℃, nitrogen flow rate 50000sccm, pressure 10000mT;

[0127] Boat departure: Time 120s, temperature set to 390℃.

[0128] Comparative Example 1

[0129] (1) Open the furnace door: the time is 25-45s, the temperature is set to 300-310℃, the nitrogen flow rate is 20000sccm, and the pressure is 10000mTor;

[0130] (2) Boat entry: time is 125-140s, temperature is set to 300-310℃, and pressure is 10000 millitor;

[0131] (3) First step: vacuuming: time is 50s, temperature is set to 300~310℃, and pressure is 10000 mTortos;

[0132] (4) Second step: Vacuuming: Time set to 200s, temperature set to 300~310℃, pressure set to 0 mTorr;

[0133] (5) Leak detection: time is 60s, temperature is set to 300~310℃, and pressure is 10000 mTortos;

[0134] (6) Vacuuming: Time is 20s, temperature is set to 300~310℃, and pressure is 0 millitor;

[0135] (7) Pressure adjustment: time is 30s, temperature is set to 300~310℃, nitrous oxide flow rate is 7450sccm, TMA flow rate is 98g / h, and pressure is 1700mTortos;

[0136] (8) Alumina deposition: time is 100-115s, temperature is set to 300-310℃, nitrous oxide flow rate is 6000sccm, TMA flow rate is 60g / h, pressure is 1700mTortos, front boat RF power discharge power is 6000W, duty cycle is 20 / 1350, rear boat RF power discharge power is 7400W, duty cycle is 20 / 1350;

[0137] (9) Vacuuming: Time is 30s, temperature is set to 445~460℃, and pressure is 0 millitor;

[0138] (10) First step of heating: time is 120s, temperature is set to 445~460℃, pressure is 0 mTorr, auxiliary heating is turned on and auxiliary heating temperature is set to 480℃.

[0139] (11) Pressure adjustment: time is 20s, temperature is set to 445~460℃, pressure is 1500 mTortos, ammonia flow rate is 5000 sccm, nitrous oxide flow rate is 5500 sccm;

[0140] (12) Hydrogen-oxygen passivation: time is 350s, temperature is set to 445~460℃, pressure is 1500 mTortos, ammonia flow rate is 5000 sccm, nitrous oxide flow rate is 5500 sccm, front boat RF power discharge power is 5000W, duty cycle is 30 / 1500, rear boat RF power discharge power is 5500W, duty cycle is 30 / 1500, auxiliary heating is turned on and auxiliary heating temperature is set to 480℃;

[0141] (13) Second step of heating: time 170s, temperature set to 445~460℃, pressure 0 mTorr, auxiliary heating turned on and auxiliary heating temperature set to 480℃.

[0142] (14) Vacuuming: Time is 15s, temperature is set to 445~460℃, and pressure is 0 millitor;

[0143] (15) Pressure adjustment: time is 15s, temperature is set to 445~460℃, pressure is 1300 mTorr, silane flow rate is 1000 sccm, nitrous oxide flow rate is 8500 sccm;

[0144] (16) Silica deposition: time is 40s, temperature is set to 445~460℃, pressure is 1300 mTortos, silane flow rate is 1000 sccm, nitrous oxide flow rate is 8500 sccm, front boat RF power discharge power is 11000W and duty cycle is 50 / 1000, rear boat power is 13000W and duty cycle is 50 / 1000;

[0145] (17) Pressure regulation: time is 15s, temperature is set to 445~460℃, pressure is 1700 mTorr, silane flow rate is 2700 sccm, ammonia flow rate is 10500 sccm.

[0146] (18) First layer silicon nitride deposition: time set to 140s, temperature set to 445~460℃, pressure set to 1700 mTorr, silane flow rate 2700 sccm, ammonia flow rate 10500 sccm, front boat RF power discharge power 14500W, duty cycle 50 / 700, rear boat power 17500W, duty cycle 50 / 650;

[0147] (19) Second layer silicon nitride deposition: time set to 150s, temperature set to 445~460℃, pressure set to 1700 mTortos, silane flow rate to 1800 sccm, ammonia flow rate to 10725 sccm, front boat RF power discharge power to 14500W, duty cycle to 50 / 650, rear boat RF power discharge power to 17500W, duty cycle to 50 / 650;

[0148] (20) Third layer silicon nitride deposition: time set to 160s, temperature set to 445~460℃, pressure set to 1700 mTortos, silane flow rate set to 1450 sccm, ammonia flow rate set to 12800 sccm, front boat RF power discharge power set to 14500W, duty cycle set to 50 / 650, rear boat RF power discharge power set to 17500W, duty cycle set to 50 / 650;

[0149] (21) Vacuuming: Time is 15s, temperature is set to 390℃, and pressure is 0 millitor;

[0150] (22) Cleaning: Time is 15s, temperature is set to 390℃, nitrogen flow rate is 20000sccm, and pressure is 0 millitor;

[0151] (23) Vacuuming: Time is 20s, temperature is set to 390℃, and pressure is 0 millitor;

[0152] (24) Back pressure: time sccm 100s, temperature set to 390℃, nitrogen flow rate 50000sccm, pressure 10000mT;

[0153] Boat departure: Time 120s, temperature set to 390℃.

[0154] Solar cells were fabricated using the tubular PECVD equipment repaired in Example 1 and Comparative Example 1, respectively, through the PECVD process. The electrical performance of the fabricated cells was tested, and the average electrical performance parameters and yield were calculated. The results are shown in Table 1 and Table 2, respectively.

[0155] Table 1

[0156]

[0157] In Table 1, Eta represents the test conversion efficiency, Isc represents the short-circuit current, Uoc represents the open-circuit voltage, FF represents the fill factor, Rs represents the series resistance, Rsh represents the parallel resistance, and IRev1 represents the dark current.

[0158] Table 2

[0159]

[0160] Experiments show that the no-load repair method for tubular PECVD equipment after maintenance provided in this embodiment of the invention optimizes the TMA and nitrous oxide flow rates, deposition power, and duty cycle settings during no-load operation, and extends the deposition time of each silicon nitride layer to 200s. The optimized process efficiency is improved by 0.05%, and the process yield is significantly improved, with a significant reduction in black edge problems.

[0161] In summary, in this embodiment, the provided no-load repair method for tubular PECVD equipment after maintenance involves placing an empty graphite boat in the furnace tube after maintenance, depositing an alumina layer inside the furnace tube, then depositing a silicon oxide layer on the alumina layer, followed by stepwise deposition of multiple silicon nitride layers on the alumina layer, and finally controlling the furnace tube to cool down and repressurize before unloading the boat. This no-load process increases the thickness of both alumina and silicon nitride, rapidly repairing the damaged film inside the furnace tube and restoring the pre-maintenance process environment. This improves upon the existing tubular PECVD equipment used for depositing alumina and SiNx as back-side passivation films, which often experiences low first-boat efficiency and poor yield after maintenance.

[0162] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0163] The above provides a detailed description of a method for repairing a tubular PECVD equipment after maintenance. Specific examples have been used to illustrate the principles and implementation methods of the invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the invention. At the same time, those skilled in the art will recognize that there will be changes in the specific implementation methods and application scope based on the ideas of the invention. Therefore, the content of this specification should not be construed as a limitation of the invention.

Claims

1. A method for restoring a tubular PECVD equipment after maintenance by running it dry, characterized in that, include: After maintenance of the tubular PECVD equipment, an empty graphite boat is placed in the furnace tube, and an alumina layer is deposited inside the furnace tube. After depositing an alumina layer, a silicon oxide layer is deposited on the alumina layer; A silicon oxide layer is deposited, and multiple silicon nitride layers are deposited stepwise on the silicon oxide layer; After depositing multiple layers of silicon nitride, the furnace tubes are cooled and pressurized before being unloaded from the boat.

2. The no-load repair method according to claim 1, characterized in that, Depositing an alumina layer inside the furnace tube includes: Under conditions of 280–350°C and 1500–2000 mTor inside the furnace tube, nitrous oxide with a flow rate of 7000–8000 sccm and trimethylaluminum gas with a flow rate of 80–120 g / h are introduced, and sputtering deposition is performed for 100–115 s to form the alumina layer inside the furnace tube.

3. The no-load repair method according to claim 2, characterized in that, During the deposition of the alumina layer inside the furnace tube, the RF power supply discharge power is 5000-10000W, and the duty cycle is 20 / 1200.

4. The no-load repair method according to claim 1, characterized in that, Depositing a silicon oxide layer on the alumina layer includes: Under conditions of 400–500°C and 1000–1500 mTor inside the furnace tube, silane with a flow rate of 800–1500 sccm and nitrous oxide with a flow rate of 5000–10000 sccm are introduced, and sputtering deposition is performed for 80–150 s to form the silicon oxide layer on the alumina layer.

5. The no-load repair method according to claim 1, characterized in that, Multilayer silicon nitride layers are deposited in steps on the silicon oxide layer, including: Under the conditions of 400-500℃ and 1500-1800mTor in the furnace tube, silane with a flow rate of 2500-3000sccm and ammonia with a flow rate of 10000-10600sccm are introduced, and sputtering deposition is performed for 180-300s to form a first silicon nitride layer on the silicon oxide layer. Under the conditions of 400-500℃ and 1500-1800mTor in the furnace tube, silane with a flow rate of 1500-2000sccm and ammonia with a flow rate of 10600-10900sccm are introduced, and sputtering deposition is performed for 180-300s to form a second silicon nitride layer on the first silicon nitride layer. Under conditions of 400–500°C and 1500–1800 mTor inside the furnace tube, silane with a flow rate of 1000–1500 sccm and ammonia with a flow rate of 1100–1500 sccm are introduced, and sputtering deposition is performed for 180–300 s to form a third silicon nitride layer on the second silicon nitride layer.

6. The no-load repair method according to claim 1, characterized in that, After depositing the alumina layer and before depositing the silicon oxide layer on the alumina layer, the method further includes: The alumina layer is then annealed.

7. The no-load repair method according to claim 6, characterized in that, Annealing the alumina layer includes: Under conditions of 400–500℃ and 0mTor pressure inside the furnace tube, heat treatment is performed for 100–150 seconds. After heat treatment, ammonia gas and nitrous oxide gas with a flow rate of 4000-6000 sccm are introduced into the furnace tube at a temperature of 400-500℃ and a pressure of 1200-1800 mTor, and the passivation reaction lasts for 200-500 seconds. After the passivation reaction, the furnace tube is heated for 150–200 seconds at a temperature of 400–500℃ and a pressure of 0 mTor.

8. The no-load repair method according to claim 1, characterized in that, After depositing multiple silicon nitride layers, the method further includes: Perform protective gas cleaning on the furnace tubes.

9. The no-load repair method according to claim 8, characterized in that, Protective gas cleaning of furnace tubes includes: Nitrogen gas is introduced into the furnace tube at a flow rate of 15,000 to 25,000 sccm at 300 to 400°C, while the pressure inside the furnace tube is controlled at 0 mTor, and this process is continued for 10 to 20 seconds.

10. The no-load repair method according to claim 1, characterized in that, Before depositing an alumina layer inside the furnace tube, the method further includes: The furnace tube is then subjected to a vacuum treatment.

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