Boron diffusion method of TOPCon battery

Abstract

The invention relates to a boron diffusion method of a TOPCon battery, and belongs to the technical field of solar battery manufacturing. Comprising the following steps: feeding into a boat, preheating and vacuumizing; leakage detection; raising the temperature; stabilizing the temperature; pre-oxidation; one-step source introduction; raising the temperature; two-step source introduction; blowing and heating; propelling; cooling is performed; returning pressure; opening a furnace pipe; and after cooling is finished, the automatic robot unloads the silicon wafers, and a four-probe sheet resistance tester is synchronously adopted to test sheet resistance data of the silicon wafers at different positions. According to the invention, the reaction gas can be uniformly distributed in the middle flow channel of the silicon wafer to form uniform diffusion, so that the problem of non-uniform diffusion of the reaction gas in the boron diffusion process can be effectively solved, and the sheet resistance uniformity of boron diffusion is improved, thereby improving the battery efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell manufacturing, and particularly to a boron diffusion method for TOPCon cells. Background Art

[0002] With the development of the photovoltaic solar energy industry, TOPCon cells have become the darling of the industry due to their obvious advantages such as high conversion efficiency, low attenuation performance, and high cost performance. Among them, the boron diffusion process is an important link in the production process. Therefore, ensuring the stability of the boron diffusion process and reducing the production cost of this process are the key points of research. The boron diffusion process is the most important link in cell production. In industrial production, boron diffusion often uses a trichloroboron gaseous source tube diffusion process, and the diffusion temperature is usually between 800°C and 950°C. In this temperature range, the diffusion reaction intermediate product B2O3 is liquid, so the uniformity of boron diffusion is far less than that of phosphorus diffusion. At the same time, this process will produce by-products BSG (boron silicate glass), and BSG will adhere to the surfaces of the quartz tube, quartz boat, and inner furnace door (quartz furnace door), affecting the diffusion effect and thus the electrical performance of TOPCon cells. Therefore, quickly and effectively solving the problem of boron diffusion uniformity is of great significance for the preparation of high-efficiency and low-cost TOPCon solar cells.

[0003] The inlet and outlet pipe structures currently used in the boron diffusion process are as Figure 1 or Figure 2 shown. In the actual production process, it is found that Figure 1 or Figure 2 the inlet and outlet gas structures shown still have the problem of uneven diffusion of reaction gas, resulting in poor uniformity of boron diffusion sheet resistance and thus relatively low cell efficiency. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a boron diffusion method for TOPCon cells. The technical solution of the present invention is as follows:

[0005] A boron diffusion method for TOPCon cells, the boron diffusion method for TOPCon cells is carried out in a quartz tube, the quartz tube adopts an improved inlet and outlet pipe structure, the inlet pipe in the improved inlet and outlet pipe structure is inserted into the quartz tube from the top of one end of the quartz tube far from its furnace door and extends to the middle of the quartz tube, and the outlet pipe in the improved inlet and outlet pipe structure is inserted into the middle of one end of the quartz tube far from its furnace door;

[0006] The boron diffusion method for TOPCon cells includes:

[0007] S1, loading the boat, preheating and evacuating;

[0008] S2, leak detection;

[0009] S3, Raise the temperature;

[0010] S4, Stabilize the temperature;

[0011] S5, Pre-oxidation: Maintain the temperature in the quartz furnace at 830 °C for 280 - 300 s. Pass a mixture of oxygen and nitrogen into the quartz tube through the inlet pipe. The flow rate of oxygen is 500 - 1000 sccm, the flow rate of nitrogen is 3000 - 3500 sccm, and at the same time, the flow rate of nitrogen at the furnace door is 500 - 1000 sccm. The pressure in the quartz tube is maintained at 130 - 200 mbar;

[0012] S6, One-step source introduction: Maintain the pressure in the quartz tube at 130 - 200 mbar. Pass a mixture of boron trichloride, oxygen, and nitrogen into the quartz tube through the inlet pipe. The flow rate of boron trichloride is 80 - 130 sccm, the flow rate of oxygen is 500 - 1000 sccm, and the flow rate of nitrogen is 3000 - 3500 sccm; at the same time, the flow rate of nitrogen at the furnace door is 500 - 1000 sccm, and the one-step source introduction time is 180 - 600 s;

[0013] S7, Raise the temperature: Raise the temperature in the quartz tube to 840 - 860 °C, and pass nitrogen into the quartz tube through the inlet pipe at a flow rate of 2000 - 5000 sccm, maintaining the pressure in the quartz tube at 130 - 200 mbar;

[0014] S8, Two-step source introduction: Maintain the pressure in the quartz tube at 130 - 200 mbar. Pass a mixture of boron trichloride, oxygen, and nitrogen into the quartz tube through the inlet pipe. The flow rate of boron trichloride is 80 - 110 sccm, the flow rate of oxygen is 500 - 1000 sccm, and the flow rate of nitrogen is 3000 - 3500 sccm; at the same time, the flow rate of nitrogen at the furnace door is 500 - 1000 sccm, and the two-step source introduction time is 200 - 600 s;

[0015] S9, Purge and raise the temperature;

[0016] S10, Advance;

[0017] S11, Lower the temperature;

[0018] S12, Backpressure;

[0019] S13, Open the furnace tube;

[0020] S14, After cooling, the automated robot unloads the wafers, and simultaneously uses a four-probe sheet resistance tester to measure the sheet resistance data of the wafers at different positions.

[0021] Optionally, the boat feeding, preheating and vacuum pumping in S1 include: feeding the quartz boat loaded with the textured silicon wafers into the standby quartz tube through the slurry rod, where the standby quartz tube has a temperature of 780 - 800 °C, and performing a vacuum pumping process on the quartz tube for 280 - 350 s.

[0022] Optionally, the temperature increase in S3 includes: after normal leak detection, increasing the temperature for 300 - 320 s to reach 830 °C inside the quartz tube; simultaneously introducing nitrogen into the quartz tube through the inlet pipe at a flow rate of 2000 - 5000 sccm to make the pressure inside the quartz tube reach 130 - 200 mbar.

[0023] Optionally, the temperature stabilization in S4 includes: maintaining at 830 °C for 120 s to evenly heat the silicon wafers inside the quartz tube, and simultaneously introducing nitrogen into the quartz tube through the inlet pipe at a flow rate of 2000 - 5000 sccm to maintain the pressure inside the quartz tube at 130 - 200 mbar.

[0024] Optionally, the purging and temperature increase in S9 includes: raising the temperature inside the quartz tube to 880 - 910 °C, and introducing nitrogen into the quartz tube through the inlet pipe at a flow rate of 2000 - 5000 sccm to maintain the pressure inside the quartz tube at 130 - 200 mbar, with a purging and temperature increase time of 120 - 180 s.

[0025] Optionally, the advancement in S10 includes: raising the temperature inside the quartz tube to 880 - 950 °C and lasting for 270 - 1000 s. During this process, nitrogen is introduced into the quartz tube through the inlet pipe at a flow rate of 2000 - 5000 sccm to maintain the pressure inside the quartz tube at 130 - 200 mbar.

[0026] Optionally, the temperature decrease in S11 includes: after the advancement ends, decreasing the temperature, reducing the temperature inside the quartz tube to 780 - 800 °C, and the temperature decrease time is 25 - 30 min.

[0027] Optionally, the pressure backfill in S12 includes: when performing pressure backfill after the temperature decrease, introducing nitrogen into the quartz tube through the inlet pipe at a flow rate of 10000 - 15000 sccm.

[0028] Optionally, the opening of the furnace tube in S13 includes: extending the slurry rod into the quartz tube to take out the quartz boat, closing the furnace door, and using the manipulator to take the quartz boat to the cooling platform for cooling.

[0029] Optionally, the length of the inlet pipe is 1.5 - 1.6 m.

[0030] All of the above optional technical solutions can be arbitrarily combined, and the present invention does not elaborate on the structures after each combination.

[0031] With the above solution, the beneficial effects of the present invention are as follows:

[0032] By setting an improved inlet and outlet gas pipe structure, the reaction gas can be evenly distributed in the middle flow channel of the silicon wafer, forming uniform diffusion, which can effectively solve the problem of uneven diffusion of the reaction gas during the boron diffusion process, improve the uniformity of the boron diffusion sheet resistance, thereby improving the battery efficiency, and can reduce the adhesion of BSG on the surface and extend the service life of the quartz furnace door. With the improved inlet and outlet gas pipe structure provided by the embodiments of the present invention in cooperation with the boron diffusion method, the debugging difficulty of the sheet resistance uniformity can be reduced, and the debugging time required can be shortened, thereby improving the production efficiency and saving the production cost.

[0033] The above description is only an overview of the technical solution of the present invention. In order to be able to more clearly understand the technical means of the present invention and implement it according to the content of the specification, the following takes the preferred embodiments of the present invention and combines with the drawings to describe in detail as follows. Brief Description of the Drawings

[0034] Figure 1 is a schematic structural diagram of an inlet and outlet gas pipe structure of a quartz tube currently used in the boron diffusion process.

[0035] Figure 2 is another schematic structural diagram of an inlet and outlet gas pipe structure of a quartz tube currently used in the boron diffusion process.

[0036] Figure 3 is a schematic diagram of an improved inlet and outlet gas pipe structure of a quartz tube used in the boron diffusion process provided by the embodiments of the present invention.

[0037] Figure 4 is a flow chart of the boron diffusion method for a TOPCon battery provided by the embodiments of the present invention.

[0038] Figure 5 is a schematic diagram of testing sheet resistance data in the embodiments of the present invention. Detailed Description of the Embodiments

[0039] The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0040] The boron diffusion method for a TOPCon battery provided by the embodiments of the present invention is carried out in a quartz tube, and the quartz tube adopts an improved inlet and outlet gas pipe structure, as Figure 3 shown. The inlet pipe in the improved inlet and outlet gas pipe structure is inserted into the quartz tube from the top of the end of the quartz tube far from its furnace door and extends to the middle of the quartz tube. The outlet pipe in the improved inlet and outlet gas pipe structure is inserted into the middle of the end of the quartz tube far from its furnace door.

[0041] On the basis of the above content, asFigure 4 As shown in Figure 4 , the boron diffusion method for TOPCon cells provided by the embodiments of the present invention includes the following steps S1 to S14:

[0042] S1, Load the boat, preheat and evacuate.

[0043] In a specific embodiment, the loading the boat, preheating and evacuating in S1 includes: feeding the quartz boat loaded with the textured silicon wafers into the standby quartz tube through the slurry rod. The standby quartz tube has a temperature of 780 - 800 °C, and the quartz tube is evacuated. The evacuation time is 280 - 350 s.

[0044] Among them, the textured silicon wafers are preferably N-type original silicon wafers with a size of 182.2 * 183.75 mm obtained by double-sided alkaline texturing. After the textured silicon wafers are loaded into the quartz boat by an automated robot, they are fed into the standby quartz tube through the silicon carbide slurry rod.

[0045] S2, Leak detection.

[0046] Specifically, after the evacuation is completed, the quartz tube is subjected to leak detection to check whether the internal air leakage of the quartz tube meets the process requirements. If it meets the process requirements, the next step is executed. Preferably, when the leak rate of the quartz tube ≤ 2 mbar / min, it is determined that the leak detection of the quartz tube meets the process requirements.

[0047] S3, Heating up.

[0048] In a specific embodiment, the heating up in S3 includes: after the leak detection is normal, heating up for 300 - 320 s to make the temperature inside the quartz tube reach 830 °C; simultaneously, nitrogen is introduced into the quartz tube through the inlet pipe, and the nitrogen flow rate is 2000 - 5000 sccm to make the pressure inside the quartz tube reach 130 - 200 mbar.

[0049] S4, Temperature stabilization.

[0050] In a specific embodiment, the temperature stabilization in S4 includes: maintaining at 830 °C for 120 s to make the silicon wafers inside the quartz tube uniformly heated, and simultaneously introducing nitrogen into the quartz tube through the inlet pipe at a flow rate of 2000 - 5000 sccm to keep the pressure inside the quartz tube at 130 - 200 mbar.

[0051] S5, Pre-oxidation: Keep the temperature in the quartz furnace at 830 °C for 280 - 300 s, introduce a mixture of oxygen and nitrogen into the quartz tube through the inlet pipe. The oxygen flow rate is 500 - 1000 sccm, the nitrogen flow rate is 3000 - 3500 sccm, and at the same time the nitrogen flow rate of the furnace door is 500 - 1000 sccm. The pressure inside the quartz tube is maintained at 130 - 200 mbar.

[0052] Among them, the furnace door nitrogen refers to the nitrogen introduced from the furnace door of the quartz tube, which is used to protect the inner furnace door of the quartz and prevent corrosion.

[0053] S6, One-step source introduction: Maintain the pressure inside the quartz tube at 130 - 200 mbar, and introduce a mixture of boron trichloride, oxygen, and nitrogen into the quartz tube through the inlet pipe. The flow rate of boron trichloride is 80 - 130 sccm, the flow rate of oxygen is 500 - 1000 sccm, and the flow rate of nitrogen is 3000 - 3500 sccm; meanwhile, the flow rate of the furnace door nitrogen is 500 - 1000 sccm, and the one-step source introduction time is 180 - 600 s.

[0054] S7, Heating up: Raise the temperature inside the quartz tube to 840 - 860 °C, and introduce nitrogen into the quartz tube through the inlet pipe at a flow rate of 2000 - 5000 sccm to maintain the pressure inside the quartz tube at 130 - 200 mbar.

[0055] S8, Two-step source introduction: Maintain the pressure inside the quartz tube at 130 - 200 mbar, and introduce a mixture of boron trichloride, oxygen, and nitrogen into the quartz tube through the inlet pipe. The flow rate of boron trichloride is 80 - 110 sccm, the flow rate of oxygen is 500 - 1000 sccm, and the flow rate of nitrogen is 3000 - 3500 sccm; meanwhile, the flow rate of the furnace door nitrogen is 500 - 1000 sccm, and the two-step source introduction time is 200 - 600 s.

[0056] S9, Purge and heating up.

[0057] In a specific embodiment, the purge and heating up in S9 includes: Raise the temperature inside the quartz tube to 880 - 910 °C, and introduce nitrogen into the quartz tube through the inlet pipe at a flow rate of 2000 - 5000 sccm to maintain the pressure inside the quartz tube at 130 - 200 mbar, and the purge and heating up time is 120 - 180 s.

[0058] S10, Advancing.

[0059] In a specific embodiment, the advancing in S10 includes: Raise the temperature inside the quartz tube to 880 - 950 °C and last for 270 - 1000 s. During the process, introduce nitrogen into the quartz tube through the inlet pipe at a flow rate of 2000 - 5000 sccm to maintain the pressure inside the quartz tube at 130 - 200 mbar.

[0060] S11, Cooling down.

[0061] In a specific embodiment, the cooling down in S11 includes: After the advancing ends, cool down the temperature inside the quartz tube to 780 - 800 °C, and the cooling down time is 25 - 30 min.

[0062] S12, Back pressure.

[0063] In a specific embodiment, the backpressure in S12 includes: when performing backpressure after cooling is completed, nitrogen is introduced into the quartz tube through the inlet pipe at a flow rate of 10,000 - 15,000 sccm. The pump stops working during backpressure.

[0064] S13, open the furnace tube.

[0065] In a specific embodiment, the opening of the furnace tube in S13 includes: inserting the slurry rod into the quartz tube to take out the quartz boat, closing the furnace door, and the manipulator takes the quartz boat to the cooling platform for cooling.

[0066] S14, after cooling is completed, the automated robot unloads the wafers, and simultaneously uses a four-probe sheet resistance tester to test the sheet resistance data of wafers at different positions.

[0067] Specifically, the four-probe sheet resistance tester uses the four-probe five-point measurement method, that is, at the center and four corners, and the points at the four corners are taken within a range of 2 cm from the edge of the wafer.

[0068] In the embodiment of the present invention, when using a four-probe sheet resistance tester to test the sheet resistance data of wafers at different positions, a fixed current is applied between two probes, and the voltage between the other two probes is measured simultaneously. Based on this measurement result, the sheet resistance data can be calculated. Specifically, as Figure 5 shown, the distance between the probes S1 = S2 = S3 = 1 mm. Assuming that the area of the thin film is infinitely large, if the current I is applied between P1 and P4, then the sheet resistance is Rs = 4.53V / I, where V is the voltage between P2 and P3.

[0069] Preferably, the length of the inlet pipe is 1.5 - 1.6 m. After the inlet pipe of this length extends into the quartz tube, it is located in the middle of the quartz tube, and the reaction gas can diffuse from the middle of the quartz tube to both sides, ensuring relatively uniform gas diffusion.

[0070] Combined with production practice, it shows that through the improved inlet and outlet pipe structure provided by the embodiment of the present invention in cooperation with the above boron diffusion method, the difficulty of debugging the sheet resistance uniformity can be reduced, and the debugging time required can be shortened, thereby improving production efficiency.

[0071] To verify the beneficial effects of the boron diffusion method of the TOPCon battery provided by the embodiment of the present invention, the following examples, Comparative Example 1 and Comparative Example 2 are provided below.

[0072] Example: Use the Figure 3 improved inlet and outlet pipe structure shown.

[0073] Take an N-type original silicon wafer with dimensions of 182.2 * 183.75 mm for double-sided alkaline texturing. Load the prepared silicon wafer into a quartz boat using an automated inserter, and then send it into a quartz tube (the total length of the quartz tube is 3.9 meters, and the length of the inlet tube is 1.5 - 1.6 meters) with a silicon carbide slurry rod. Perform the boron diffusion process by the method provided in the embodiment of the present invention. After the process is completed, use a four-probe to measure the sheet resistance at different positions and calculate the intra-wafer and inter-wafer uniformity.

[0074] Comparative Example 1: Adopt Figure 1 The inlet and outlet pipe structure shown.

[0075] Take an N-type original silicon wafer with dimensions of 182.2 * 183.75 mm for double-sided alkaline texturing. Load the prepared silicon wafer into a quartz boat using an automated inserter, and then send it into a quartz tube (the total length of the quartz tube is 3.9 meters, and the length of the inlet tube is 0.3 - 0.5 meters) to run the traditional boron diffusion process. After the process is completed, use a four-probe to measure the sheet resistance at different positions and calculate the intra-wafer and inter-wafer uniformity.

[0076] Comparative Example 2: Adopt Figure 2 The inlet and outlet pipe structure shown.

[0077] Take an N-type original silicon wafer with dimensions of 182.2 * 183.75 mm for double-sided alkaline texturing. Load the prepared silicon wafer into a quartz boat using an automated inserter, and then send it into a quartz tube (the total length of the quartz tube is 3.9 meters, and the length of the inlet tube is 3.4 - 3.45 meters) to run the traditional boron diffusion process. After the process is completed, use a four-probe to measure the sheet resistance at different positions and calculate the intra-wafer and inter-wafer uniformity.

[0078] It should be noted that the examples, Comparative Example 1, and Comparative Example 2 need to be ensured to be carried out continuously in the same quartz tube; the sheet resistance test wafers should be taken at the same position.

[0079] The sheet resistance data of the examples, Comparative Example 1, and Comparative Example 2 are shown in Table 1.

[0080] Table 1

[0081]

[0082]

[0083] It can be obtained from Table 1 that the sheet resistance of the silicon wafers obtained by the method provided in the embodiment of the present invention is more uniform than that of the comparative examples.

[0084] Furthermore, the above examples, Comparative Example 1, and Comparative Example 2 prepare solar cells through the process shown in Table 2 below, and the efficiency of the solar cells is shown in Table 3.

[0085] Table 2

[0086]

[0087] Table 3

[0088] Efficiency Eta Uoc Isc FF Rs Rsh IRev2 Example 26.364 0.7342 13.976 86.03 0.0011 1372 0.062 Comparative Example 1 26.339 0.7334 13.97 86.05 0.001 1371 0.063 Comparative Example 2 26.346 0.7337 13.971 86.04 0.0012 1330 0.064 Example - Comparative Example 1 0.025 0.0008 0.006 -0.02 0.0001 1 -0.001 Example - Comparative Example 2 0.018 0.0005 0.005 -0.01 -1E-04 42 -0.002

[0089] As can be seen from Table 2, the efficiency (Eta) of the cell prepared by the method provided in the embodiment of the present invention is relatively high.

[0090] In summary, the method provided in the embodiment of the present invention has the following advantages:

[0091] 1. The sheet resistance uniformity of boron diffusion is better; it ensures the passivation performance of the cell and improves the efficiency of the cell.

[0092] 2. The difficulty of adjusting the sheet resistance uniformity is small, and the time required for debugging is short;

[0093] 3. Since the inlet pipe is far from the quartz furnace door, the adhesion of BSG on the surface is reduced, and the service life of the quartz furnace door is extended;

[0094] 4. The line opening speed is increased, and the machine utilization rate is increased.

[0095] The above is only the preferred embodiment of the present invention and is not used to limit the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A boron diffusion method for TOPCon batteries, characterized in that: The boron diffusion method of the TOPCon battery is carried out in a quartz tube, and the quartz tube adopts an improved inlet and outlet pipe structure, wherein the inlet pipe in the improved inlet and outlet pipe structure is inserted into the quartz tube from the top of one end of the quartz tube away from the furnace door and extends to the middle of the quartz tube, and the outlet pipe in the improved inlet and outlet pipe structure is inserted into the middle of one end of the quartz tube away from the furnace door; The boron diffusion method of the TOPCon cell includes: S1, enter the boat, preheat and evacuate; S2, leak detection; S3, heating; S4, steady temperature; S5, pre-oxidation: maintain the temperature of 830°C in the quartz furnace for 280-300s, introduce a mixed gas of oxygen and nitrogen into the quartz tube through the air inlet pipe, the flow rate of oxygen is 500-1000sccm, the flow rate of nitrogen is 3000-3500sccm, and the flow rate of nitrogen at the furnace door is 500-1000sccm, and the pressure in the quartz tube is maintained at 130-200mbar; S6, one-step source passing: maintain the pressure in the quartz tube at 130-200 mbar, introduce a mixed gas of boron trichloride, oxygen and nitrogen into the quartz tube through the air inlet pipe, the flow rate of boron trichloride is 80-130 sccm, the flow rate of oxygen is 500-1000 sccm, and the flow rate of nitrogen is 3000-3500 sccm; at the same time, the flow rate of nitrogen at the furnace door is 500-1000 sccm, and the one-step source passing time is 180-600 s; S7, heating: raising the temperature in the quartz tube to 840-860° C., and introducing nitrogen gas into the quartz tube through the gas inlet pipe at a flow rate of 2000-5000 sccm, maintaining the pressure in the quartz tube at 130-200 mbar; S8, two-step source passing: maintain the pressure in the quartz tube at 130-200 mbar, and introduce a mixed gas of boron trichloride, oxygen and nitrogen into the quartz tube through the air inlet pipe, with the flow rate of boron trichloride being 80-110 sccm, the flow rate of oxygen being 500-1000 sccm, and the flow rate of nitrogen being 3000-3500 sccm; at the same time, the flow rate of nitrogen at the furnace door is 500-1000 sccm, and the two-step source passing time is 200-600 s; S9, purge and temperature rise; S10, propulsion; S11, cooling; S12, back pressure; S13, open the furnace tube; S14, after cooling, the automated robot unloads the wafer, and simultaneously uses a four-probe square resistance tester to test the square resistance data of the silicon wafer at different positions.

2. The boron diffusion method of TOPCon battery according to claim 1, characterized in that: The steps of putting the boat in, preheating and evacuating in S1 include: sending the quartz boat with the silicon wafer after texturing into the standby quartz tube through a slurry rod, the temperature of the standby quartz tube is 780-800°C, and evacuating the quartz tube for 280-350s.

3. The boron diffusion method of TOPCon battery according to claim 1, characterized in that: The heating in S3 includes: heating after the leak detection is normal, the heating time is 300-320s, so that the temperature in the quartz tube reaches 830°C; nitrogen is simultaneously introduced into the quartz tube through the air inlet pipe, the nitrogen flow rate is 2000-5000sccm, so that the pressure in the quartz tube reaches 130-200mbar.

4. The boron diffusion method of TOPCon battery according to claim 1, characterized in that: The temperature stabilization in S4 includes: maintaining the temperature at 830° C. for 120 seconds so that the silicon wafer in the quartz tube is evenly heated, and simultaneously introducing nitrogen gas into the quartz tube through the air inlet pipe at a flow rate of 2000-5000 sccm so that the pressure in the quartz tube is maintained at 130-200 mbar.

5. The boron diffusion method of TOPCon battery according to claim 1, characterized in that: The purging and heating in S9 includes: raising the temperature in the quartz tube to 880-910° C., and introducing nitrogen into the quartz tube through the air inlet pipe at a flow rate of 2000-5000 sccm, maintaining the pressure in the quartz tube at 130-200 mbar, and the purging and heating time is 120-180 s.

6. The boron diffusion method of TOPCon battery according to claim 1, characterized in that: The advancement in S10 includes: raising the temperature in the quartz tube to 880-950° C. and maintaining it for 270-1000 s, during which nitrogen is introduced into the quartz tube through the air inlet pipe at a flow rate of 2000-5000 sccm to maintain the pressure in the quartz tube at 130-200 mbar.

7. The boron diffusion method of TOPCon battery according to claim 1, characterized in that: The cooling in S11 includes: cooling after the advancement is completed, reducing the temperature in the quartz tube to 780-800° C., and the cooling time is 25-30 minutes.

8. The boron diffusion method of TOPCon battery according to claim 1, characterized in that: The back pressure in S12 includes: after the temperature reduction is completed, nitrogen is introduced into the quartz tube through the air inlet pipe at a flow rate of 10000-15000 sccm during the back pressure.

9. The boron diffusion method of TOPCon battery according to claim 1, characterized in that: The furnace tube opening in S13 includes: extending the slurry rod into the quartz tube to take out the quartz boat, closing the furnace door, and taking the quartz boat to the cooling platform for cooling by a robot.

10. The boron diffusion method of TOPCon battery according to claim 1, characterized in that: The length of the air inlet pipe is 1.5-1.6m.

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