Saturation treatment method of quartz boat for diffusion and saturated quartz boat

Abstract

The embodiment of the invention provides a saturation treatment method of a quartz boat for diffusion and a saturated quartz boat, and the saturation treatment method of the quartz boat provided by the embodiment of the invention comprises the following steps: firstly, placing the cleaned quartz boat in a diffusion furnace, carrying out protective gas cleaning in a low-pressure environment of 50-500mbar, and then, carrying out vacuum drying on the cleaned quartz boat; and then baking the quartz boat under the purging of protective gas and oxygen to obtain the saturated quartz boat. Wherein low-speed saturation can be carried out in a low-pressure environment of 50-500 mbar, the saturation treatment requirement can be met only with small gas flow, and the gas use cost and environmental pollution are reduced; meanwhile, nitrogen and oxygen are introduced during high-temperature baking, acid gas generated in the process of reacting the saturated boat can be utilized, and waste gas generated in the reaction can be taken away by utilizing the nitrogen, so that the problems of low head boat efficiency caused by pollution in a diffusion furnace behind the saturated boat and poor boat tooth mark caused by insufficiency of the saturated boat are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of crystalline silicon solar cell manufacturing, and particularly to a saturation treatment method for a quartz boat used in diffusion and a saturated quartz boat. Background Art

[0002] Currently, in the process of manufacturing solar cell wafers by diffusion, a quartz boat is generally used as a wafer carrier.

[0003] During the use of the quartz boat, due to the residue of silicon powder and the contamination of liquid carried by wet process, the quartz boat must be periodically cleaned to ensure its cleanliness. However, after the quartz boat is cleaned and put on the production line, problems such as low efficiency of the first boat dark chips and quartz boat prints are likely to occur. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a saturation treatment method for a quartz boat used in diffusion and a saturated quartz boat, so as to solve the problem that when the existing quartz boat is used again after cleaning, it is easy to cause quartz boat prints on the manufactured solar cell wafers.

[0005] To solve the above problems, the present invention is realized by the following technical solutions:

[0006] The present invention provides a saturation treatment method for a quartz boat after cleaning in diffusion, which includes:

[0007] Placing the cleaned quartz boat in a diffusion furnace, and performing protective gas cleaning under the condition that the pressure is 50 - 500 mbar;

[0008] After the protective gas cleaning, baking the quartz boat under the condition that the pressure is 50 - 500 mbar and with the purge of protective gas and oxygen to obtain a saturated quartz boat.

[0009] Further, in the saturation treatment method, during the baking process of the quartz boat, the nitrogen flow rate is 500 - 2000 sccm and the oxygen flow rate is 100 - 800 sccm.

[0010] Further, in the saturation treatment method, the temperature of the baking process is 800 - 1000 °C and the time is 10 - 30 min.

[0011] Further, in the saturation treatment method, performing the protective gas cleaning includes:

[0012] Introducing nitrogen into the diffusion furnace at a flow rate of 500 - 2000 sccm at 800 - 1000 °C, controlling the pressure in the diffusion furnace at 50 - 500 mbar, and lasting for 1 - 10 min.

[0013] Further, in the saturation treatment method, before performing the protective gas cleaning under the condition of a pressure of 50 to 500 mbar, the method further includes:

[0014] Evacuating the diffusion furnace.

[0015] Further, in the saturation treatment method, evacuating the diffusion furnace includes:

[0016] Controlling the temperature of the diffusion furnace to be 800 to 1000 °C and controlling the pressure to drop to 50 to 500 mbar.

[0017] Further, in the saturation treatment method, after the baking treatment, the method further includes:

[0018] Controlling the diffusion furnace to cool down to 700 to 790 °C, then introducing nitrogen into the diffusion furnace, and taking out the saturated quartz boat when the internal and external air pressures are the same.

[0019] Further, in the saturation treatment method, during the process of controlling the diffusion furnace to cool down to 700 to 800 °C, the nitrogen flow rate is 500 to 2000 sccm and the oxygen flow rate is 100 to 800 sccm.

[0020] Further, in the saturation treatment method, after evacuating the diffusion furnace and before performing the protective gas cleaning under the condition of a pressure of 50 to 500 mbar, the method further includes:

[0021] Performing a vacuum leak detection on the diffusion furnace.

[0022] The embodiment of the present invention also provides a saturated quartz boat, which is obtained by saturation treatment by the method as described above.

[0023] Compared with the prior art, the embodiment of the present invention has the following advantages:

[0024] In the embodiment of the present invention, in the saturation treatment method of the provided quartz boat, the cleaned quartz boat is first placed in the diffusion furnace, and the protective gas cleaning is performed in a low-pressure environment of 50 to 500 mbar, and then the quartz boat is baked under the purge of the protective gas and oxygen to obtain a saturated quartz boat. Among them, the low-pressure environment of 50 to 500 mbar can perform slow saturation, and only a small gas flow rate is required to meet the saturation treatment requirements, reducing the gas usage cost and environmental pollution; at the same time, when baking at a high temperature, nitrogen and oxygen are introduced, and the acid gas evaporated during the saturation process of the boat by the reaction of oxygen can be utilized, and the waste gas generated by the reaction is carried away by nitrogen, thereby improving the problems of low efficiency of the first boat caused by pollution in the diffusion furnace after saturation of the boat and poor boat tooth marks caused by insufficient saturation of the boat.

[0025] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and do not limit the present application. Description of the Drawings

[0026] Figure 1 is a flowchart of the saturation treatment method after cleaning the quartz boat for diffusion provided by an embodiment of the present invention. Detailed Embodiments

[0027] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0028] An embodiment of the present invention provides a saturation treatment method after cleaning a quartz boat for diffusion, as Figure 1 shown, including steps 101 to 102:

[0029] Step 101: Place the cleaned quartz boat in a diffusion furnace and perform a protective gas cleaning under the condition that the pressure is 50 to 500 mbar.

[0030] In the above step 101, first place the cleaned quartz boat in the diffusion furnace, then control the pressure in the furnace to be 50 to 500 mbar, and use the protective gas for cleaning, which can evacuate and remove the acid gas carried by the quartz boat in the diffusion furnace and the quartz powder on the quartz boat pages, ensuring the cleanliness of the tube. Among them, the above protective gas is a stable gas that is not easy to react with the quartz boat, such as nitrogen, inert gas, etc.

[0031] Among them, the low-pressure environment of 50 to 500 mbar enables the cleaning treatment requirements to be achieved with only a small flow rate of the protective gas, reducing the gas usage cost and environmental pollution.

[0032] In practical applications, the cleaned quartz boat can be a quartz boat that has carried silicon wafers for diffusion treatment and has been cleaned with a mixture of HF, HCL, and water. The above diffusion treatment can specifically be boron diffusion or phosphorus diffusion treatment.

[0033] The above step of placing the cleaned quartz boat in the diffusion furnace includes: opening the diffusion furnace, placing the cleaned quartz boat on the machine temporary storage rack, inputting the set boat number to make a reservation for the boat baking process, the manipulator lifting the boat to the furnace paddle, and sending the quartz boat into the furnace cavity and then closing the furnace door.

[0034] Step 102: After the protective gas cleaning, bake the quartz boat under the condition that the pressure is 50 to 500 mbar and the protective gas and oxygen are purged to obtain a saturated quartz boat.

[0035] In the above step 102, after the purge gas cleaning, a protective gas and oxygen are introduced under a furnace pressure of 50 to 500 mbar to bake the quartz boat, so as to utilize the acid gas evaporated during the saturation process of the boat by the reaction of oxygen, and use nitrogen to carry away the waste gas generated by the reaction, realizing further cleaning of the diffusion furnace and the quartz boat.

[0036] In practical applications, after the saturation process is completed, the tube is taken out from the paddle position, and the manipulator lifts the saturated quartz boat to the temporary storage rack for convenient subsequent normal use.

[0037] In the pretreatment method of the quartz boat provided by the embodiment of the present invention, the cleaned quartz boat is first placed in a diffusion furnace, and purge gas cleaning is carried out in a low-pressure environment of 50 to 500 mbar, and then the quartz boat is baked under the purging of a protective gas and oxygen to obtain a saturated quartz boat. Among them, the low-pressure environment of 50 to 500 mbar can perform slow saturation, and only a small gas flow rate is required to meet the saturation treatment requirements, reducing the gas usage cost and environmental pollution; at the same time, nitrogen and oxygen are introduced during high-temperature baking, and the acid gas evaporated during the saturation process of the boat by the reaction of oxygen can be utilized, and nitrogen is used to carry away the waste gas generated by the reaction, thereby improving the problems of low efficiency of the first boat caused by pollution in the diffusion furnace after saturation of the boat and poor boat tooth marks caused by insufficient saturation of the boat.

[0038] Optionally, in one embodiment, the purge gas cleaning of the quartz boat includes:

[0039] Nitrogen is introduced into the diffusion furnace at a flow rate of 500 to 2000 sccm at 800 to 1000 °C, the pressure in the diffusion furnace is controlled at 50 to 500 mbar, and it lasts for 1 to 10 minutes.

[0040] In this embodiment, by keeping the pressure in the diffusion furnace at 50 to 500 mbar, introducing nitrogen at a flow rate of 500 to 2000 sccm when the temperature reaches 800 to 1000 °C, and lasting for 1 to 10 minutes, such as one of 1 minute, 2 minutes, 5 minutes, 10 minutes or a range value between any two of them, the water vapor carried by the quartz boat in the diffusion furnace and the quartz powder on the quartz boat itself can be fully evacuated by the low-flow nitrogen, ensuring the cleanliness of the diffusion furnace.

[0041] Optionally, in some embodiments, during the purge gas cleaning process, the pressure of the diffusion furnace is controlled to be one of 50 mbar, 100 mbar, 200 mbar, 500 mbar or a range value between any two of them, the temperature is controlled to be one of 800 °C, 880 °C, 900 °C, 1000 °C or a range value between any two of them, and the nitrogen flow rate is controlled to be one of 500 sccm, 800 sccm, 1000 sccm, 1500 sccm, 2000 sccm or a range value between any two of them.

[0042] In some embodiments, a protective gas cleaning is performed, including: introducing nitrogen into the diffusion furnace at a flow rate of 1000 sccm at 880 °C, controlling the pressure in the diffusion furnace to 100 mTor, and lasting for 5 min.

[0043] Optionally, in one embodiment, before performing the protective gas cleaning, the method further includes step 1001:

[0044] Step 1001: evacuating the diffusion furnace.

[0045] In this embodiment, before performing the protective gas cleaning, the diffusion furnace is first evacuated to remove impurities such as water vapor and oxygen in the diffusion furnace, facilitating more thorough cleaning of the quartz boat by the subsequent protective gas.

[0046] Optionally, in a specific embodiment, evacuating the diffusion furnace includes:

[0047] Controlling the temperature of the diffusion furnace to 800 - 1000 °C and controlling the pressure to drop to 50 - 500 mbar.

[0048] In this specific embodiment, the method of raising the temperature and pumping down the pressure is adopted, that is, raising the temperature in the diffusion furnace to 800 - 1000 °C and controlling the pressure to drop to 50 - 500 mbar, so that the inside of the diffusion furnace is in a low-pressure state and lasts for a predetermined time to complete the evacuation of the diffusion furnace. Among them, the above-mentioned predetermined time can be 1 - 5 min; in some embodiments, the above-mentioned predetermined time can be one of 1 min, 2 min, 3 min, 4 min, 5 min or a range value between any two of them.

[0049] Optionally, in some embodiments, evacuating the diffusion furnace includes: after raising the temperature of the diffusion furnace to 880 °C, evacuating to 100 mbar and maintaining for 3 min.

[0050] Optionally, in one embodiment, after the above step 1001 and before the above step 101, the method for saturating the quartz boat provided by the embodiments of the present invention further includes step 1002: performing a vacuum leak detection on the diffusion furnace.

[0051] In this embodiment, first open the vacuum pump at a temperature of 800 - 1000 °C to reduce the pressure in the diffusion furnace to 50 - 500 mtorr and maintain for 0.5 - 5 min for leak detection, that is, the airtightness of the diffusion furnace can be confirmed by simulating the low-pressure environment of the subsequent baking treatment.

[0052] Optionally, in one embodiment, during the baking process of the quartz boat, the nitrogen flow rate is 500 - 2000 sccm and the oxygen flow rate is 100 - 800 sccm.

[0053] In this embodiment, since the high-temperature baking is carried out in a low-pressure environment with a furnace pressure of 50 - 500 mbar, only nitrogen with a flow rate of 500 - 2000 sccm and oxygen with a flow rate of 100 - 800 sccm need to be introduced. In this way, the acid gas generated during the saturation process of the boat can be fully reacted with oxygen, and the exhaust gas from the reaction can be carried away by nitrogen.

[0054] Optionally, in one embodiment, the temperature of the above baking process is 800 - 1000 °C and the time is 10 - 30 min.

[0055] In this embodiment, by using the method of heating and baking, the temperature of the diffusion furnace is raised to 800 - 1000 °C, and the vacuum pump is controlled to continuously operate to maintain the pressure at 50 - 500 mbar for 10 - 30 min. By using nitrogen with a flow rate of 500 - 2000 sccm and oxygen with a flow rate of 100 - 800 sccm, the acid gas generated during the saturation process of the boat can be fully reacted with oxygen, and the exhaust gas from the reaction can be carried out of the diffusion furnace by nitrogen, so as to realize the cleaning treatment of the quartz boat page.

[0056] Optionally, in one embodiment, the saturation treatment method of the quartz boat provided by the embodiment of the present invention further includes after the baking treatment:

[0057] After controlling the diffusion furnace to cool down to 700 - 800 °C, nitrogen is introduced into the diffusion furnace, and when the internal and external pressures are the same, the saturated quartz boat is taken out.

[0058] In this embodiment, after the saturation treatment of the quartz boat is completed, first control the temperature of the diffusion furnace to decrease to 700 - 800 °C, then introduce a protective gas such as nitrogen to control the back pressure of the diffusion furnace to reach the external pressure, and then open the furnace door to end the saturation treatment process, and the saturated quartz boat is obtained.

[0059] Optionally, in a specific embodiment, 5000 - 20000 sccm of nitrogen can be introduced and the pressure in the diffusion furnace can be controlled to the atmospheric pressure state such as 1060 mbar to make the pressure inside the furnace reach the external pressure for opening the furnace door, and then the saturation treatment process of the quartz boat can be ended; after the saturation treatment process is ended, the saturated quartz boat is taken out from the paddle position pipe, and the manipulator lifts the saturated quartz boat to the temporary storage rack for convenient subsequent normal use.

[0060] Optionally, in a specific embodiment, during the process of controlling the diffusion furnace to cool down to 700 - 800 °C, the nitrogen flow rate is 500 - 2000 sccm and the oxygen flow rate is 100 - 800 sccm.

[0061] In this specific embodiment, during the cooling process, nitrogen with a flow rate of 500 - 2000 sccm and oxygen with a flow rate of 100 - 800 sccm are continuously introduced, and the pressure inside the furnace is maintained at a low pressure of 50 - 500 mbar. This can not only achieve the cooling process for subsequent boat unloading but also further clean the diffusion furnace and the quartz boat.

[0062] Optionally, the diffusion furnace can be controlled to cool down to a value within the range of one of 700 °C, 750 °C, 780 °C, 800 °C or any range between any two of them.

[0063] The embodiment of the present invention also provides a saturated quartz boat, which is saturated and processed by the above method.

[0064] For the above embodiment of the saturated quartz boat, it is processed by the above method and can achieve the same technical effects. To avoid repetition, it will not be elaborated here. For relevant parts, refer to the partial description of the embodiment of the saturation treatment method of the quartz boat.

[0065] The present invention will be described in detail below through embodiments.

[0066] Example 1

[0067] (1). Open the diffusion furnace door: Set the temperature to 780 °C, introduce nitrogen with a flow rate of 5000 sccm, control the furnace pressure to normal pressure of 1060 mbar, and the time is 30 s.

[0068] (2). Load the boat: Load the cleaned quartz boat into the diffusion furnace, set the temperature to 780 °C, introduce nitrogen with a flow rate of 5000 sccm, control the furnace pressure to normal pressure of 1060 mbar, and maintain the time for 10 min.

[0069] (3). Vacuum pumping: Raise the temperature to 880 °C, turn on the vacuum pump, and evacuate the inside of the diffusion furnace to 100 mbar, and maintain the time for 3 min.

[0070] (4). Leak detection: Control the furnace pressure to maintain 100 mbar, and maintain the time for 1 min.

[0071] (5). High-temperature cleaning: After leak detection, turn on the vacuum pump, pump the pressure to 100 mbar, and at the same time continue to raise the temperature to 880 °C, introduce nitrogen with a flow rate of 1000 sccm and maintain for 5 min.

[0072] (6). High-temperature baking: Maintain the temperature at 880 °C and the pressure at 100 mbar, and at the same time introduce oxygen with a flow rate of 500 sccm and nitrogen with a flow rate of 1000 sccm, and continue for 15 min.

[0073] (7) Cooling: Control the temperature to drop to 800 °C, maintain the pressure at 100 mbar, and simultaneously introduce oxygen with a flow rate of 500 sccm and nitrogen with a flow rate of 1000 sccm, and continue for 10 min.

[0074] (8) Backpressure: When the temperature drops to 780 °C, introduce nitrogen with a flow rate of 10000 sccm, control the pressure to rise back to normal pressure of 1060 mbar and continue for 3 min.

[0075] (9) Boat removal: Introduce nitrogen with a flow rate of 5000 sccm, control the pressure to maintain normal pressure of 1060 mbar and continue for 10 min, so that the pressure inside the furnace reaches the external air pressure to open the furnace door, end the saturation treatment process, and obtain a saturated quartz boat.

[0076] Example 2

[0077] (1) Open the diffusion furnace door: Set the temperature to 780 °C, introduce nitrogen with a flow rate of 5000 sccm, control the furnace pressure to normal pressure of 1060 mbar, and the time is 30 s.

[0078] (2) Boat loading: Load the cleaned quartz boat into the diffusion furnace, set the temperature to 780 °C, introduce nitrogen with a flow rate of 5000 sccm, control the furnace pressure to normal pressure of 1060 mbar, and maintain for 10 min.

[0079] (3) Vacuum pumping: Raise the temperature to 800 °C, turn on the vacuum pump, evacuate the diffusion furnace to 50 mbar, and maintain for 1 min.

[0080] (4) Leak detection: Control the furnace pressure to maintain 50 mbar and maintain for 0.5 min.

[0081] (5) High-temperature cleaning: After leak detection, turn on the vacuum pump, pump the pressure to 50 mbar, and at the same time continue to raise the temperature to 800 °C, introduce nitrogen with a flow rate of 500 sccm and maintain for 1 min.

[0082] (6) High-temperature baking: Maintain the temperature at 800 °C and the pressure at 50 mbar, and simultaneously introduce oxygen with a flow rate of 100 sccm and nitrogen with a flow rate of 500 sccm, and continue for 10 min.

[0083] (7) Cooling: Control the temperature to drop to 780 °C and the pressure to maintain 50 mbar, and simultaneously introduce oxygen with a flow rate of 100 sccm and nitrogen with a flow rate of 500 sccm, and continue for 10 min.

[0084] (8) Backpressure: When the temperature drops to 700 °C, introduce nitrogen with a flow rate of 10000 sccm, control the pressure to rise back to normal pressure of 1060 mbar and continue for 3 min.

[0085] (9) Boat removal: Introduce nitrogen with a flow rate of 5000 sccm, control the pressure to maintain atmospheric pressure of 1060 mbar and continue for 10 min, so that the pressure inside the furnace reaches the external air pressure to open the furnace door, end the saturation treatment process, and obtain a saturated quartz boat.

[0086] Example 3

[0087] (1) Open the diffusion furnace door: Set the temperature to 780 °C, introduce nitrogen with a flow rate of 5000 sccm, control the furnace pressure to atmospheric pressure of 1060 mbar, and the time is 30 s.

[0088] (2) Boat loading: Load the cleaned quartz boat into the diffusion furnace, set the temperature to 780 °C, introduce nitrogen with a flow rate of 5000 sccm, control the furnace pressure to atmospheric pressure of 1060 mbar, and maintain for 10 min.

[0089] (3) Vacuum pumping: Raise the temperature to 1000 °C, turn on the vacuum pump, evacuate the diffusion furnace to 500 mbar, and maintain for 5 min.

[0090] (4) Leak detection: Control the furnace pressure to maintain 500 mbar and maintain for 5 min.

[0091] (5) High-temperature cleaning: After leak detection, turn on the vacuum pump, pump the pressure down to 500 mbar, while continuing to raise the temperature to 1000 °C, introduce nitrogen with a flow rate of 2000 sccm and maintain for 10 min.

[0092] (6) High-temperature baking: Maintain the temperature at 1000 °C and the pressure at 500 mbar, while introducing oxygen with a flow rate of 800 sccm and nitrogen with a flow rate of 2000 sccm, and continue for 30 min.

[0093] (7) Temperature reduction: Control the temperature to drop to 850 °C and the pressure to maintain 500 mbar, while introducing oxygen with a flow rate of 800 sccm and nitrogen with a flow rate of 2000 sccm, and continue for 10 min.

[0094] (8) Pressure recovery: When the temperature drops to 790 °C, introduce nitrogen with a flow rate of 10000 sccm, control the pressure to rise back to atmospheric pressure of 1060 mbar and continue for 3 min.

[0095] (9) Boat removal: Introduce nitrogen with a flow rate of 5000 sccm, control the pressure to maintain atmospheric pressure of 1060 mbar and continue for 10 min, so that the pressure inside the furnace reaches the external air pressure to open the furnace door, end the saturation treatment process, and obtain a saturated quartz boat.

[0096] Comparative Example 1

[0097] (1). Open the diffusion furnace door: Set the temperature to 780 °C, introduce nitrogen with a flow rate of 10000 sccm, control the furnace pressure at atmospheric pressure 1060 mbar, and the time is 30 s.

[0098] (2). Load the boat: Load the cleaned quartz boat into the diffusion furnace, set the temperature to 780 °C, introduce nitrogen with a flow rate of 10000 sccm, control the furnace pressure at atmospheric pressure 1060 mbar, and maintain for 10 min.

[0099] (3). High-temperature cleaning: Raise the temperature to 880 °C, introduce nitrogen with a flow rate of 5000 sccm, control the furnace pressure at atmospheric pressure 1060 mbar and maintain for 30 min.

[0100] (4). Cool down: Control the temperature to drop to 780 °C and maintain for 10 min.

[0101] (5). Unload the boat: Introduce nitrogen with a flow rate of 5000 sccm, control the pressure to maintain atmospheric pressure 1060 mbar and continue for 10 min, so that the pressure inside the furnace reaches the external air pressure to open the furnace door, end the saturation treatment process, and obtain a saturated quartz boat.

[0102] Use the saturated quartz boats obtained in Examples 1 to 3 and Comparative Example 1 respectively to fabricate solar cell wafers through the diffusion process. The specific operation steps of the diffusion process are as follows:

[0103] (1). Open the furnace door: Set the temperature to 780 °C, introduce nitrogen with a flow rate of 10000 sccm, atmospheric pressure 1060 mbar, and the time is 30 s;

[0104] (2). Load the boat: Load the textured silicon wafers into the diffusion furnace, set the temperature to 780 °C, introduce nitrogen with a large flow rate of 10000 sccm, atmospheric pressure 1060 mbar, and maintain for 10 min;

[0105] (3). Vacuum pumping: Pump the inside of the diffusion furnace to a vacuum of 100 mbar and maintain for 4 min;

[0106] (4). Leak detection: Maintain the pressure at 100 mbar and continue for 60 s;

[0107] (5). Raise temperature and pump pressure: After leak detection, pump the pressure to 50 mbar, and at the same time raise the temperature to 790 °C, introduce nitrogen with a large flow rate of 1700 sccm, pressure 50 mbar, and maintain for 5 min;

[0108] (6). Pre-oxidation: Maintain the temperature at 790 °C, and at the same time introduce oxygen with a flow rate of 600 sccm, nitrogen with a large flow rate of 600 sccm, nitrogen with a small flow rate of 500 sccm, pressure 50 mbar, and the oxidation time is 3 min;

[0109] (7) First deposition: Maintain the temperature at 790 °C, while introducing oxygen at a flow rate of 600 sccm, POCl3 at a flow rate of 600 sccm, nitrogen at a flow rate of 500 sccm, a pressure of 50 mbar, and a deposition time of 5 min;

[0110] (8) Heating: Raise the temperature to 810 °C, introduce large nitrogen at a flow rate of 1000 sccm, small nitrogen at a flow rate of 700 sccm, a pressure of 50 mbar, and a heating time of 3 min;

[0111] (9) Second deposition: Maintain the temperature at 810 °C, while introducing oxygen at a flow rate of 600 sccm, POCl3 at a flow rate of 600 sccm, nitrogen at a flow rate of 500 sccm, a pressure of 50 mbar, and a deposition time of 4 min;

[0112] (10) Heating and advancing: Raise the temperature to 860 °C, introduce large nitrogen at a flow rate of 1000 sccm, small nitrogen at a flow rate of 700 sccm, a pressure of 50 mbar, and an advancing time of 8 min;

[0113] (11) Constant temperature pushing and oxygen boosting: Maintain the temperature at 860 °C, introduce large nitrogen at a flow rate of 600 sccm, small nitrogen at a flow rate of 700 sccm, oxygen at a flow rate of 400 sccm, a pressure of 50 mbar, and a pushing time of 11 min;

[0114] (12) Cooling: Lower the temperature to 820 °C for 15 min;

[0115] (13) Oxidation: Lower the temperature to 810 °C, introduce large nitrogen at a flow rate of 1500 sccm, oxygen at a flow rate of 600 sccm, raise the pressure to 100 mbar, and an oxidation time of 3 min;

[0116] (14) Third deposition: Maintain the temperature at 810 °C, while introducing oxygen at a flow rate of 750 sccm, POCl3 at a flow rate of 1200 sccm, nitrogen at a flow rate of 450 sccm, maintain a pressure of 100 mbar, and a deposition time of 3 min;

[0117] (15) Cooling: Lower the temperature to 805 °C, introduce large nitrogen at a flow rate of 1400 sccm, small nitrogen at a flow rate of 700 sccm, maintain a pressure of 100 mbar, for 3 min;

[0118] (16) Fourth deposition: Maintain the temperature at 805 °C, while introducing oxygen at a flow rate of 750 sccm, POCl3 at a flow rate of 1350 sccm, nitrogen at a flow rate of 500 sccm, maintain a pressure of 100 mbar, and a deposition time of 8 min;

[0119] (17). Post-oxidation: Temperature is 790 °C, oxygen flow rate is 3000 sccm, large nitrogen flow rate is 1000 sccm, pressure is increased to 200 mbar, and oxidation time is 90 s;

[0120] (18). Inflating and back-pressurizing: Large nitrogen flow rate is 10000 sccm, small nitrogen flow rate is 2000 sccm, pressure is restored to normal pressure of 1060 mbar and maintained for 4 min;

[0121] (19). Removing the boat: Large nitrogen flow rate is 5000 sccm, pressure is maintained at normal pressure of 1060 mbar, and the time lasts for 10 min to end the process.

[0122] The electrical performance of the fabricated solar cells is tested, and the results are shown in Table 1; among them, the test criteria are as follows: ① The nominal efficiency requirement is Class A ≥ 22.5%, Class B ≥ 19.0%; ② The efficiency deviation requires that the range of single-pack efficiency ≤ 0.4%, and the single-pack average value ≥ the nominal value; ③ The parallel resistance (Ω) ≥ 50; ④ The dark current (A@-12V) < 0.8; ⑤ The average bifaciality: ≥ 75%, single piece: ≥ 70%.

[0123] Table 1

[0124]

[0125] 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 value, Rsh represents the parallel resistance value, and IRev1 represents the dark current.

[0126] The fabricated solar cells are statistically analyzed for black spots, black dots, scratches, boat tooth marks, dirt, and dark wafers, and the results are shown in Table 2.

[0127] Table 2

[0128]

[0129] Experiments show that the saturation treatment method of the quartz boat provided by the embodiments of the present invention uses low-pressure and low-flow protective gas cleaning combined with oxygen purging for high-temperature baking. The efficiency of the solar cells fabricated using the saturated quartz boat processed by the process of the present invention is increased by 0.025% compared with the conventional process, the EL yield is increased by 2.4%, and the proportion of quartz boat marks and dark wafers of the produced solar cells can be significantly reduced.

[0130] In summary, in this embodiment, in the provided saturation treatment method for the quartz boat, the cleaned quartz boat is first placed in a diffusion furnace, and protective gas cleaning is carried out in a low-pressure environment of 50 to 500 mbar. Then, the quartz boat is baked under the purge of the protective gas and oxygen to obtain a saturated quartz boat. Among them, the low-pressure environment of 50 to 500 mbar can perform slow saturation, and only a small gas flow rate is required to meet the saturation treatment requirements, reducing the gas usage cost and environmental pollution. At the same time, when baking at high temperature, nitrogen and oxygen are introduced. The acid gas evaporated during the saturation process of the boat by the reaction of oxygen can be utilized, and the waste gas generated by its reaction can be carried away by nitrogen, thereby improving the problems of low efficiency of the first boat caused by pollution in the diffusion furnace after saturation of the boat and poor boat tooth marks caused by insufficient saturation of the boat.

[0131] Although the preferred embodiments of the embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they know the basic creative concept. Therefore, the claims are intended to be construed to include the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0132] The above provides a detailed introduction to a saturation treatment method and a saturated quartz boat for a diffusion quartz boat provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention. At the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A saturation treatment method after cleaning a quartz boat for diffusion, characterized in that, Including: Placing the cleaned quartz boat in a diffusion furnace and performing protective gas cleaning under the condition that the pressure is 50 - 500 mbar; After the protective gas cleaning, baking the quartz boat under the condition that the pressure is 50 - 500 mbar and with protective gas and oxygen purging to obtain a saturated quartz boat.

2. The saturation treatment method according to claim 1, wherein During the baking process of the quartz boat, the nitrogen flow rate is 500 - 2000 sccm and the oxygen flow rate is 100 - 800 sccm.

3. The saturation treatment method according to claim 1, wherein, The temperature of the baking process is 800 - 1000 °C and the time is 10 - 30 min.

4. The pretreatment method according to claim 1, characterized in that Performing protective gas cleaning includes: Introducing nitrogen into the diffusion furnace at a flow rate of 500 - 2000 sccm at 800 - 1000 °C, controlling the pressure in the diffusion furnace to be 50 - 500 mbar, and lasting for 1 - 10 min.

5. The saturation treatment method according to claim 1, wherein Before performing protective gas cleaning under the condition that the pressure is 50 - 500 mbar, the method further includes: Evacuating the diffusion furnace.

6. The saturation treatment method according to claim 5, characterized in that, Evacuating the diffusion furnace includes: Controlling the temperature of the diffusion furnace to be 800 - 1000 °C and controlling the pressure to drop to 50 - 500 mbar.

7. The saturation treatment method according to claim 1, wherein After the baking process, the method further includes: Controlling the diffusion furnace to cool down to 700 - 800 °C, then introducing protective gas into the diffusion furnace, and taking out the saturated quartz boat when the internal and external air pressures are the same.

8. The saturation treatment method according to claim 7, characterized in that, During the process of controlling the diffusion furnace to cool down to 700 - 800 °C, the nitrogen flow rate is 500 - 2000 sccm and the oxygen flow rate is 100 - 800 sccm.

9. The saturation treatment method according to claim 5, characterized in that After evacuating the diffusion furnace and before performing protective gas cleaning under the condition that the pressure is 50 - 500 mbar, the method further includes: Performing vacuum leak detection on the diffusion furnace.

10. A saturated quartz boat, characterized in that, Obtained by saturation treatment using the method according to any one of claims 1 - 9.

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