Boron diffusion wet oxygen process after texturing based on N-type TOPCon battery
By using the oxidation form of dry oxygen-wet oxygen combined with hydrogen and water-oxygen in the preparation process of N-type TOPCon battery, the process parameters are adjusted, the damage problem of boron diffusion process to quartz components is solved, the equipment life and capacity stability are improved, and the production cost is reduced.
Patent Information
- Application Number
- CN202510383380.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-28
- Publication Date
- 2025-07-11
AI Technical Summary
During the preparation of existing N-type TOPCon batteries, the high temperature conditions required by the boron diffusion process cause damage to the life of quartz parts and equipment stability, resulting in unstable production capacity and increased production costs.
Using the oxidation form of dry oxygen and wet oxygen combined, the process time, steps and flow rate are adjusted in the oxidation process after the two-in-one boron diffusion process, the temperature is reduced, and the diffusion coefficient difference between hydroxyl and oxygen in silicon is used to assist in enhancing oxidation.
It improves the service life of the equipment, improves the stability of production capacity, and reduces equipment losses and related maintenance time and costs caused by damage to quartz parts.
Smart Images
Figure CN120302749A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of methods for processing tunneling oxide passivated contact solar cells, especially the boron diffusion wet oxygen process. Background Art
[0002] In the existing N-type TOPCon cell technology route, boron diffusion is a process step for doping boron element on the front side of the cell. Generally, a low-pressure tube diffusion furnace is used to introduce boron source (usually BCl3), oxygen, and nitrogen. After BCl3 reacts with oxygen to form B2O3, a displacement reaction occurs with the silicon wafer to generate boron and silicon oxide, and then high-temperature diffusion is carried out to achieve the doping purpose. In the existing process, the conditions required for boron doping (the peak temperature is usually 1040 °C) are higher than those for conventional phosphorus doping (the temperature is usually 760 - 860 °C), and it has approached the maximum temperature tolerance limit of the quartz tube. The maximum temperature that the existing industrial quartz tube can withstand is generally 1100 °C. It starts to soften at 1020 °C and will damage the service life of quartz components such as quartz boats and quartz tubes. Due to the production output requirements in industrial production, the single-boat wafer loading capacity of the existing general equipment quartz tube reaches 2784 pcs, which is much larger than the 1624 pcs per boat in the PERC cell era.
[0003] Based on the above, the larger single-boat load capacity of the quartz tube, and the need to match higher temperature conditions and more high-temperature process times. For example, in an environment of 1040 °C - 1050 °C, the working time needs to be as long as about 85 minutes. This poses a higher test for the service life of quartz components such as quartz tubes and quartz boats, the quality of quartz tubes, and the sealing of the furnace tube, bringing risks of unstable production capacity and increased production costs. Summary of the Invention
[0004] In view of at least one of the above technical problems, the present invention provides a boron diffusion wet oxygen process based on N-type TOPCon cell texturing, which utilizes the different diffusion coefficients of hydroxyl and oxygen in silicon, and uses the form of combined dry oxygen and wet oxygen oxidation in the oxidation link after the two-in-one boron diffusion process to assist in enhancing oxidation. Based on this, the process time, process steps, flow rate, and temperature are readjusted and allocated to improve the service life of the equipment, enhance the stability of production capacity, and reduce equipment losses caused by damage to quartz components and related maintenance time and costs. The specific technical solutions are as follows:
[0005] A boron diffusion wet oxygen process based on N-type TOPCon cell texturing includes the following steps:
[0006] S1, Place the textured silicon wafer into a quartz boat and then place the whole into the preheated inner cavity of the furnace tube;
[0007] S2, Evacuate the furnace tube to 450 mbar and simultaneously perform the first temperature increase;
[0008] S3. Maintain the temperature and pressure of the furnace tube; introduce O2 and N2 for oxidation, with the nitrogen flow rate at the furnace mouth being 1000 - 2000 sccm;
[0009] S4. Introduce O2, N2, and BCl3 for reaction; maintain the nitrogen flow rate at the furnace mouth while conducting the second temperature increase;
[0010] S5. Introduce the protective gas N2 into the furnace tube for the third temperature increase; the nitrogen flow rate at the furnace mouth is 2000 - 3000 sccm;
[0011] S6. Introduce O2 for oxidation propulsion, conduct the fourth temperature increase, maintain the nitrogen flow rate at the furnace mouth, and adjust the furnace tube pressure to 800 mbar;
[0012] S7. Maintain the temperature and pressure inside the furnace tube, and conduct oxidation with a combination of dry and wet oxygen; among them, during the dry oxygen oxidation stage, the nitrogen flow rate at the furnace mouth is 1500 - 2500 sccm, and during the wet oxygen oxidation stage, the nitrogen flow rate at the furnace mouth is 2000 - 3000 sccm;
[0013] S8. Reduce the temperature while maintaining the pressure, and conduct oxidation by introducing N2 throughout the process;
[0014] S9. Introduce N2 for backpressure to break the vacuum, and take out the quartz boat containing the silicon wafers in the furnace tube.
[0015] In some embodiments of the present disclosure, in the step S1, the preheating temperature of the inner cavity of the furnace tube is 780 - 810 °C.
[0016] In some embodiments of the present disclosure, in the step S2, the temperature increase in the first time is 820 - 830 °C, and the time is 10 - 15 min; among them, when the furnace tube is evacuated to 450 mbar, the inlet and outlet channels are closed, and a leak detection test of the furnace tube is conducted. After passing the test, enter step S3.
[0017] In some embodiments of the present disclosure, in the step S4, the O2 flow rate is 200 - 1000 sccm, the N2 flow rate is 5000 - 8000 sccm, the BCl3 flow rate is 50 - 300 sccm, and the duration is 5 - 15 min; the second temperature increase is to raise the temperature to 830 - 840 °C.
[0018] In some embodiments of the present disclosure, in the step S5, the third temperature increase is to raise the temperature to 900 - 1000 °C, N2 is introduced throughout the process as protection, the time is 10 - 15 min, and the N2 flow rate is 5000 - 10000 sccm.
[0019] In some embodiments of the present disclosure, in the step S6, the fourth temperature increase is to raise the temperature to 1000 - 1020 °C, the time is 20 - 50 min, and the O2 flow rate is 10000 - 15000 sccm.
[0020] In some embodiments of the present disclosure, in step S7, wet oxidation is first performed. During wet oxidation, 12,000 sccm of O2 is introduced throughout the process while N2 is introduced. N2 flows through a humidifying device equipped with pure water, and the N2 carrying water vapor mixes with O2 and enters the furnace tube for oxidation for 15 - 30 minutes. Then, dry oxidation is performed. During dry oxidation, the introduction of N2 carrying water vapor is stopped, and 12,000 sccm of O2 is continuously introduced throughout the process for isothermal oxidation for 20 - 30 minutes.
[0021] In some embodiments of the present disclosure, in step S7, dry oxidation is first performed. During dry oxidation, N2 and 12,000 sccm of O2 are introduced for isothermal oxidation for 20 - 30 minutes. Then, wet oxidation is performed. During wet oxidation, 12,000 sccm of O2 is introduced throughout the process while N2 is introduced. N2 flows through a humidifying device equipped with pure water, and the N2 carrying water vapor mixes with O2 and enters the furnace tube for oxidation for 15 - 30 minutes.
[0022] In some embodiments of the present disclosure, the purity of the pure water is ≥5N, the water temperature is 70 - 80°C, and the saturated vapor pressure is 30 - 47 kPa; the water vapor content of the N2 carrying water vapor is 15.8% - 25.6%.
[0023] In some embodiments of the present disclosure, in step S8, first, 9,000 sccm of O2 and 3,000 sccm of N2 are introduced for pipeline purging for 3 minutes. The furnace tube pressure is 800 mbar, and the nitrogen flow rate at the furnace mouth is 2,000 sccm. Then, the temperature is reduced to 750°C, and 12,000 sccm of N2 is introduced throughout the process for oxidation for 42 minutes. The furnace tube pressure is 800 mbar, and the nitrogen flow rate at the furnace mouth is 2,000 sccm.
[0024] Compared with the prior art, the above-mentioned wet oxygen process for boron diffusion after texturing of N-type TOPCon cells has the following beneficial effects:
[0025] 1. This technical solution utilizes the different diffusion coefficients of hydroxyl groups and oxygen in silicon, and uses a combination of dry oxygen and wet oxygen oxidation in the oxidation link after the two-in-one boron diffusion process to assist in enhancing oxidation. Based on this, the process time, process steps, flow rate, and temperature are readjusted and allocated, reducing the temperature, thereby improving the service life of the equipment, enhancing the stability of production capacity, and reducing equipment losses and related maintenance time and costs caused by damage to quartz components.
[0026] 2. The method of nitrogen bubbling can effectively avoid the negative defects of oxygen carrying water vapor on the wet oxygen process.
[0027] 3. It brings new technical inspiration to the semiconductor boron diffusion wet oxygen process. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 Schematic diagram of the intake pipeline in the present invention;
[0029] Figure 2 Schematic diagram of the correlation between the pure water temperature and the oxide layer thickness during the wet and dry oxygen combined oxidation stage;
[0030] Description of the reference numerals in the figure: 1. BCl3 gas source; 2. O2 gas source; 3. N2 gas source; 4. Pure water; 5. Furnace tube. Detailed implementation manners
[0031] In order to better understand the purpose, structure and function of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. It should be noted that unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used herein in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "including" and "provided with" and any variations thereof in this application are in an open-ended writing and are intended to cover non-exclusive inclusion.
[0032] As shown in the attached drawings Figure 1 A wet oxygen process for boron diffusion after texturing based on N-type TOPCon cells is designed, which mainly includes the following steps:
[0033] S1. Place the textured silicon wafer into a quartz boat and then place the whole into the inner cavity of the furnace tube at 780 - 810 °C;
[0034] S2. Pump the furnace tube to a vacuum of 450 mbar, and at the same time heat it up to 820 - 830 °C for 10 - 15 min;
[0035] S3. Keep the furnace tube temperature and pressure; Introduce O2 and N2 for oxidation for 2 - 6 min, and the nitrogen flow rate at the furnace mouth is 1000 - 2000 sccm;
[0036] S4. Introduce O2, N2 and BCl3 to react, the O2 flow rate is 200 - 1000 sccm, the N2 flow rate is 5000 - 8000 sccm, the BCl3 flow rate is 50 - 300 sccm, and the time is 5 - 15 min; Keep the nitrogen flow rate at the furnace mouth; Raise the temperature to 830 - 840 °C;
[0037] S5. Introduce the protective gas N2 into the furnace tube and heat it up to 900 - 1000 °C; The N2 flow rate is 5000 - 10000 sccm, and the nitrogen flow rate at the furnace mouth is 2000 - 3000 sccm;
[0038] S6. Introduce O2 for oxidation promotion for 20 - 50 minutes, set the temperature to 1000 - 1020 °C, the O2 flow rate is 10000 - 15000 sccm, maintain the nitrogen flow rate at the furnace mouth, and the furnace tube pressure returns to 800 mbar;
[0039] S7. Maintain the temperature and pressure inside the furnace tube, and perform combined dry and wet oxygen oxidation; among them, the nitrogen flow rate at the furnace mouth during the dry oxygen oxidation stage is 1500 - 2500 sccm, and the nitrogen flow rate at the furnace mouth during the wet oxygen oxidation stage is 2000 - 3000 sccm;
[0040] S8. Reduce the temperature while maintaining the pressure, and introduce N2 throughout the process for oxidation, with the nitrogen flow rate at the furnace mouth being 2000 sccm;
[0041] S9. Introduce N2 to back - pressure and break the vacuum, and take out the quartz boat containing silicon wafers in the furnace tube.
[0042] Based on the above, the main process of the wet oxygen process for boron diffusion ends.
[0043] This technical solution utilizes the different diffusion coefficients of hydroxyl and oxygen in silicon, and uses the form of combined dry and wet oxygen oxidation in the oxidation stage after the two - in - one boron diffusion process to assist in enhancing oxidation. Based on this, the process time, process steps, flow rate, and temperature are readjusted and allocated, thereby improving the service life of the equipment, enhancing the stability of production capacity, and reducing the equipment losses and related maintenance time and costs caused by the damage of quartz components.
[0044] In the above embodiments, two examples will be listed to implement the above - mentioned technical solution. The mention of "example" in this article means that the specific features, structures, or characteristics described in combination with the example can be included in at least one embodiment of the present application. The appearance of this phrase at various positions in the specification does not necessarily refer to the same example, nor is it an independent or alternative example mutually exclusive with other examples. Without conflict, the various embodiments in the present application can be combined with each other.
[0045] As Figures 1 to 2 shown, Example 1 discloses a wet oxygen process for boron diffusion after texturing of N - type TOPCon cells, which mainly includes the following steps:
[0046] S1. Place the quartz boat containing the textured silicon wafers into the furnace tube 5, and the pre - heating temperature of the inner cavity of the furnace tube 5 is 780 - 810 °C. In this example, the temperature inside the furnace tube 5 is set to 800 °C.
[0047] S2. Pre-evacuate to 700 mbar, then evacuate the furnace tube 5 to 450 mbar. The first temperature increase is from 820 to 830 °C, and the time is 10 to 15 min. In this embodiment, the first temperature increase is to 825 °C and the time is 12 min. After leak detection, when the pressure of the furnace tube 5 is pumped to 450 mbar, close the inlet and outlet valves to conduct a leak detection test on the furnace tube 5.
[0048] S3. Pre-oxygen stage: Oxidation is carried out by continuously introducing O2 and N2 throughout the process. The O2 flow rate is 200 to 1000 sccm, the N2 flow rate is 5000 to 8000 sccm, the BCl3 flow rate is 50 to 300 sccm, and the duration is 5 to 15 min. In this embodiment, the O2 flow rate is 1500 sccm, the N2 flow rate is 1500 sccm, the time is 4 min, and the pressure of the furnace tube 5 is 450 mbar. The nitrogen flow rate at the furnace mouth is 1000 to 2000 sccm. In this embodiment, the nitrogen flow rate at the furnace mouth is 1500 sccm.
[0049] S4. React by continuously introducing O2, N2, and BCl3 through the BCl3 gas source 1, O2 gas source 2, and N2 gas source 3 throughout the process. The O2 flow rate is 200 to 1000 sccm, the N2 flow rate is 5000 to 8000 sccm, the BCl3 flow rate is 50 to 300 sccm, and the duration is 5 to 15 min. The second temperature increase is to 830 to 840 °C.
[0050] The specific process of step S4 in this embodiment is as follows:
[0051] Gas source I: The O2 flow rate is 400 sccm, the N2 flow rate is 7000 sccm, the BCl3 flow rate is 100 sccm, the time is 2 min, and the nitrogen flow rate at the furnace mouth is 2000 sccm.
[0052] Advance: Protect by continuously introducing N2 throughout the process. The N2 flow rate is 7000 sccm, the time is 3 min, the pressure of the furnace tube 5 is 450 mbar, the temperature rises to 835 °C, and the nitrogen flow rate at the furnace mouth is 2500 sccm.
[0053] Gas source II: React by continuously introducing O2, N2, and BCl3 throughout the process. The O2 flow rate is 400 sccm, the N2 flow rate is 7000 sccm, the BCl3 flow rate is 100 sccm, the time is 3.5 min, and the nitrogen flow rate at the furnace mouth is 2000 sccm.
[0054] Advance: Protect by continuously introducing N2 throughout the process. The N2 flow rate is 7000 sccm, the time is 3 min, the pressure of the furnace tube 5 is 450 mbar, the temperature rises to 845 °C, and the nitrogen flow rate at the furnace mouth is 2500 sccm.
[0055] Tongyuan III, O2, N2, and BCl3 are introduced throughout the process for reaction. The O2 flow rate is 400 sccm, the N2 flow rate is 7000 sccm, the BCl3 flow rate is 100 sccm, the time is 3.5 min, and the nitrogen flow rate at the furnace mouth is 2000 sccm;
[0056] Purge, N2 is introduced throughout the process for purging. The N2 flow rate is 7000 sccm, the time is 3 min, the pressure of furnace tube 5 remains unchanged, the temperature is set at 850 °C, and the nitrogen flow rate at the furnace mouth is 2000 sccm.
[0057] S5, Temperature increase and advancement. The third temperature increase is to raise the temperature to 900 - 1000 °C. N2 is introduced throughout the process as protection. The time is 10 - 15 min, the N2 flow rate is 5000 - 10000 sccm. In this embodiment, the time is 12 min, the temperature is set at 900 °C, N2 is introduced throughout the process as protection, the nitrogen flow rate is 7000 sccm, and the nitrogen flow rate at the furnace mouth is 2500 sccm.
[0058] S6, Temperature increase with dry oxygen. In step S6, the fourth temperature increase is to raise the temperature to 1000 - 1020 °C, the time is 20 - 50 min, and the O2 flow rate is 10000 - 15000 sccm. In this embodiment, the time is 40 min, the temperature is set at 1000 °C, O2 is introduced throughout the process for oxidation advancement, the O2 flow rate is 12000 sccm, the nitrogen flow rate at the furnace mouth is 2000 sccm, and the pressure of furnace tube 5 is set at 800 mbar.
[0059] S7, Maintain the temperature and pressure inside furnace tube 5, and perform oxidation with a combination of dry and wet oxygen; among them, the nitrogen flow rate at the furnace mouth during the dry oxygen oxidation link is 1500 - 2500 sccm, and the nitrogen flow rate at the furnace mouth during the wet oxygen oxidation link is 2000 - 3000 sccm.
[0060] In this embodiment, the pre - opening valve process is adopted. The time is 10 seconds, the temperature is 1000 °C, the valve is opened in advance, the O2 flow rate is 12000 sccm, the nitrogen flow rate at the furnace mouth is 2000 sccm, and the pressure of furnace tube 5 is 800 mbar.
[0061] First, perform wet oxygen oxidation. O2 and N2 carrying water vapor are used for oxidation. Throughout the process, 12000 sccm of O2 is introduced through O2 gas source 2, and at the same time, 2000 sccm of N2 is introduced through N2 gas source 3 and flows through a container filled with pure water 4. A glass bottle can be used. N2 bubbles are blown into the bottle, so that N2 carrying water vapor is mixed with O2 and enters furnace tube 5 for oxidation, as Figure 1As shown, the time is 15 - 30 min. In this embodiment, the set time is 20 min, the pressure of the furnace tube 5 is 800 mbar, the temperature is 1000 °C, and the nitrogen flow rate at the furnace mouth is 2000 sccm; among them, the purity of the pure water ≥ 5N, the water temperature is 70 - 80 °C, and the saturated vapor pressure is 30 - 47 kpa; the water vapor content of N2 carrying water vapor is 15.8% - 25.6%. When the water temperature is too high or too low, it will affect the vapor pressure of saturated water vapor, thus affecting the water vapor content carried by the water-carrying nitrogen, and thus affecting the water vapor content required for the process, such as Figure 2 As shown: Under the same process conditions, the process time, steps, and gas flow rate are the same. When the temperature of the constant temperature box is lower than 70 °C, the thickness of the oxide layer formed at this time is relatively thin, not reaching the conventional thickness of about 90 - 110 nanometers. When the temperature rises to 85 °C, due to the too high water vapor content, the boron diffusion oxide layer is relatively loose, which may cause over-etching on the front side of the cell in subsequent processes and cannot meet the requirements of subsequent processes.
[0062] Then, dry oxygen oxidation is carried out. Stop the introduction of N2 carrying water vapor, and continue to introduce 12000 sccm of O2 throughout the process for constant temperature oxidation. The time is 20 - 30 min. In this implementation, the set time is 25 min, the temperature is 1000 °C, the pressure of the furnace tube 5 is 800 mbar, and the nitrogen flow rate at the furnace mouth is 2000 sccm.
[0063] S8, nitrogen purging. Continue to introduce 9000 sccm of O2 and 3000 sccm of N2 throughout the process for pipeline purging. The time is 3 min, the pressure of the furnace tube 5 is 800 mbar, and the nitrogen flow rate at the furnace mouth is 2000 sccm.
[0064] Cooling down. Cool down to 750 °C, and introduce 12000 sccm of N2 throughout the process for oxidation. The time is 42 min, the pressure of the furnace tube 5 is 800 mbar, and the nitrogen flow rate at the furnace mouth is 2000 sccm.
[0065] S9, backpressure and boat removal. Introduce nitrogen to break the vacuum, and take out the quartz boat containing silicon wafers in the furnace tube 5. The process ends.
[0066] Embodiment 2 discloses a wet oxygen process for boron diffusion after texturing of N-type TOPCon cells. The difference between this embodiment and Embodiment 1 lies in step S7:
[0067] First, dry oxygen oxidation is carried out. Introduce N2, and continue to introduce 12000 sccm of O2 throughout the process for constant temperature oxidation. The time is 20 - 30 min. In this implementation, the set time is 25 min, the temperature is 1000 °C, the pressure of the furnace tube 5 is 800 mbar, and the nitrogen flow rate at the furnace mouth is 2000 sccm.
[0068] Then, wet oxidation is carried out, and oxidation is performed with O2 and N2 carrying water vapor. 12000 sccm of O2 is introduced throughout the process, and at the same time, 2000 sccm of N2 is introduced to flow through a container filled with pure water. A pure water bottle can be used, and N2 bubbles are blown into the bottle to make the N2 carrying water vapor mix with O2 and enter the furnace tube 5 for oxidation. The time is 15 - 30 min. In this embodiment, the set time is 20 min, the pressure of the furnace tube 5 is 800 mbar, the temperature is 1000 °C, and the nitrogen flow rate at the furnace mouth is 2000 sccm; among them, the purity of the pure water ≥ 5N, the water temperature is 70 - 80 °C, and the saturated vapor pressure is 30 - 47 kPa; the water vapor content of the N2 carrying water vapor is 15.8% - 25.6%.
[0069] It has been experimentally proven that during post-oxidation, either wet oxidation first or dry oxidation first can achieve the effect of shortening the process time and reducing the process peak temperature.
[0070] In this experiment, three single-boat quartz tubes were used for comparison. The initial wafer loading of each single-boat was 2787 pcs, and 1200 pcs of wafers were taken from the same part of each single-boat quartz tube. The number of silicon wafers that entered the electrical performance test link after removing the process losses through the conventional dry oxidation process in the first single-boat quartz tube was 1080 pcs. The number of silicon wafers that entered the electrical performance test link after removing the process losses through the process described in Example 1 in the second single-boat quartz tube was 1078 pcs; the number of silicon wafers that entered the electrical performance test link after removing the process losses through the process described in Example 2 in the third single-boat quartz tube was 1088 pcs.
[0071] The following Table 1 shows the comparison results of the electrical performance parameter experiments on the silicon wafers after the conventional dry oxidation process and the processes described in Examples 1 and 2. As can be seen from Table 1, compared with the traditional process, the conversion efficiency of this technical solution can be increased by 0.016% - 0.019%. In Table 1, Eta represents the conversion efficiency, Isc represents the short-circuit current, Voc represents the open-circuit voltage, IRev2 represents the reverse leakage current, Rs represents the series resistance, Rsh represents the parallel resistance, and FF represents the fill factor.
[0072] Table 1 Comparison results of conventional dry oxidation and wet oxidation experiments in Examples 1 and 2
[0073] Item Number of tests Eta Voc Isc FF IRev2 Rs Rsh Control group 1080 26.038 0.7433 16.047 83.35 0.015 0.0019 1927.53 Example 1 1078 26.054 0.7435 16.043 83.41 0.0169 0.0019 1976.3 Example 1 1088 26.057 0.7431 16.04 83.47 0.0137 0.0019 2007.87
[0074] It can be understood that the above description is only for explaining the specific implementation manners of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be covered within the disclosure scope of the present application.
Claims
1. A wet oxygen process for boron diffusion after texturing of N-type TOPCon cells, characterized in that It includes the following steps: S1. Place the textured silicon wafer into a quartz boat and then place the whole into the preheated inner cavity of the furnace tube; S2. Evacuate the furnace tube to 450 mbar and at the same time conduct the first temperature rise; S3. Maintain the temperature and pressure of the furnace tube; Introduce O2 and N2 for oxidation, and the nitrogen flow rate at the furnace mouth is 1000 - 2000 sccm; S4. Introduce O2, N2 and BCl3 for reaction; Maintain the nitrogen flow rate at the furnace mouth and at the same time conduct the second temperature rise; S5. Introduce the protective gas N2 into the furnace tube and conduct the third temperature rise; The nitrogen flow rate at the furnace mouth is 2000 - 3000 sccm; S6. Introduce O2 for oxidation push, conduct the fourth temperature rise, maintain the nitrogen flow rate at the furnace mouth, and adjust the furnace tube pressure to 800 mbar; S7. Maintain the temperature and pressure inside the furnace tube and conduct oxidation by combining dry oxygen and wet oxygen; Among them, in the dry oxygen oxidation stage, the nitrogen flow rate at the furnace mouth is 1500 - 2500 sccm, and in the wet oxygen oxidation stage, the nitrogen flow rate at the furnace mouth is 2000 - 3000 sccm; S8. Reduce the temperature while maintaining the pressure, and introduce N2 throughout the process for oxidation; S9. Introduce N2 to backpressure to break the vacuum and take out the quartz boat containing the silicon wafer in the furnace tube.
2. The wet oxygen process for boron diffusion after texturing of the N-type TOPCon cell according to claim 1, wherein, In the step S1, the preheating temperature of the inner cavity of the furnace tube is 780 - 810 °C.
3. The wet oxygen process for boron diffusion after texturing of the N-type TOPCon cell according to claim 1, wherein In the step S2, the temperature of the first temperature rise is 820 - 830 °C and the time is 10 - 15 min; Among them, when the furnace tube is evacuated to 450 mbar, close the inlet and outlet channels, conduct a leak detection test on the furnace tube, and enter step S3 after passing the test.
4. The wet oxygen process for boron diffusion after texturing of the N-type TOPCon cell according to claim 1, wherein In the step S4, the O2 flow rate is 200 - 1000 sccm, the N2 flow rate is 5000 - 8000 sccm, the BCl3 flow rate is 50 - 300 sccm, and the duration is 5 - 15 min; The second temperature rise is to raise the temperature to 830 - 840 °C.
5. The wet oxygen process for boron diffusion after texturing of an N-type TOPCon cell according to claim 1, characterized in that, In the step S5, the third temperature rise is to raise the temperature to 900 - 1000 °C, introduce N2 throughout the process as protection, the time is 10 - 15 min, and the N2 flow rate is 5000 - 10000 sccm.
6. The wet oxygen process for boron diffusion after texturing of an N-type TOPCon cell according to claim 1, wherein In the step S6, the fourth temperature rise is to raise the temperature to 1000 - 1020 °C, the time is 20 - 50 min, and the O2 flow rate is 10000 - 15000 sccm.
7. The wet oxygen process for boron diffusion after texturing of the N-type TOPCon cell according to claim 1, characterized in that, In the step S7, first conduct wet oxygen oxidation. The wet oxygen oxidation is to introduce 12000 sccm of O2 throughout the process while introducing N2. The N2 flows through a humidifying device equipped with pure water, and the N2 carrying water vapor mixes with O2 and enters the furnace tube for oxidation, and the time is 15 - 30 min; Then conduct dry oxygen oxidation. The dry oxygen oxidation is to stop introducing the N2 carrying water vapor and continue to introduce 12000 sccm of O2 throughout the process for constant temperature oxidation, and the time is 20 - 30 min.
8. The wet oxygen process for boron diffusion after texturing of the N-type TOPCon cell according to claim 1, wherein In the step S7, first conduct dry oxygen oxidation. The dry oxygen oxidation is to introduce N2 and 12000 sccm of O2 for constant temperature oxidation, and the time is 20 - 30 min; Then conduct wet oxygen oxidation. The wet oxygen oxidation is to introduce 12000 sccm of O2 throughout the process while introducing N2. The N2 flows through a humidifying device equipped with pure water, and the N2 carrying water vapor mixes with O2 and enters the furnace tube for oxidation, and the time is 15 - 30 min.
9. The wet oxygen process for boron diffusion after texturing of the N-type TOPCon cell according to claim 7 or 8, characterized in that The purity of the pure water is ≥5N, the water temperature is 70-80°C, and the saturated vapor pressure is 30-47 kPa; the water vapor content of N2 carrying water vapor is 15.8%-25.6%.
10. The wet oxygen process for boron diffusion after texturing of an N-type TOPCon cell according to claim 1, wherein In the step S8, first introduce 9000 sccm of O2 and 3000 sccm of N2 for pipeline purging for 3 minutes, the furnace tube pressure is 800 mbar, and the nitrogen flow rate at the furnace mouth is 2000 sccm. Then cool down to 750°C, and introduce 12000 sccm of N2 throughout the process for oxidation for 42 minutes, the furnace tube pressure is 800 mbar, and the nitrogen flow rate at the furnace mouth is 2000 sccm.
Citation Information
Cited By
Preparation method of solar cell, solar cell and photovoltaic module
CN121310698A