A method for preparing a high-density anti-reflection film of a TOPCon cell tubular PECVD based on power optimization

Abstract

This invention discloses a power-optimized method for preparing a high-density antireflective film using PECVD in a TOPCon cell, relating to the field of solar cells. The method includes: setting a gradient reaction power under a consistent process environment to determine the optimal power for silicon nitride and silicon oxynitride, respectively; and depositing silicon nitride and silicon oxynitride films based on the optimal power combination. By designing a stepped power experiment, the deposition power of each functional layer in the antireflective film is independently and systematically optimized. Finally, a specific power combination that maximizes cell efficiency is adopted, which reduces light reflection from the silicon surface, increases light absorption by the cell, and enhances the passivation effect of the silicon nitride and silicon oxynitride films on the cell, thereby significantly improving the cell's conversion efficiency.

Description

Technical Field

[0001] This invention relates to the field of solar cells, specifically to a method for preparing a high-density antireflection film for TOPCon cells using tubular PECVD based on power optimization, and the TOPCon cell structure. Background Technology

[0002] TOPCon (Tunnel Oxide Passivated Contact) cells are a high-efficiency crystalline silicon solar cell technology. Their core structure involves forming an ultrathin tunnel oxide layer (typically 1-2 nm SiO2) and a doped polycrystalline silicon layer on the back of the cell, achieving excellent surface passivation and selective carrier transport, significantly improving open-circuit voltage and conversion efficiency. On the front side of a TOPCon cell, one or more layers of silicon nitride (SiNx:H) films are typically deposited. These films serve a dual function: antireflection (reducing surface reflection loss by controlling the refractive index) and bulk / surface passivation (passivating dangling bonds and defects within the silicon mass by releasing hydrogen atoms), which is crucial for enhancing the cell's photoelectric performance.

[0003] Currently, the mainstream equipment for depositing SiNx:H thin films in mass production is the tube-type plasma enhanced chemical vapor deposition (PECVD) system, which has advantages such as high capacity, good uniformity, mature technology, and controllable cost, and can meet the demand for high-quality passivation and antireflection films in large-scale high-efficiency TOPCon cell manufacturing.

[0004] In the mass production deposition of this thin film using tubular PECVD, radio frequency (RF) power is one of the key process parameters affecting film density. Insufficient RF power leads to inadequate plasma intensity, incomplete reaction, a loose film, poor density, and ineffective passivation. Excessive RF power, on the other hand, may cause ion bombardment damage to the existing passivation layer on the silicon wafer surface (such as the boron emitter), also resulting in performance degradation. Therefore, finding an optimal power point that balances film density and surface damage for specific battery structures (such as TOPCon) and specific equipment is crucial for improving battery efficiency.

[0005] Existing technologies typically employ an empirically based fixed power value or experiment within a wide range, lacking a systematic, data-driven power optimization method tailored to the specific structure of TOPCon batteries. This makes it impossible to precisely lock in the optimal process window, resulting in the battery efficiency failing to reach its full potential. Summary of the Invention

[0006] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a method for preparing a high-density antireflection film for TOPCon batteries using tubular PECVD based on power optimization, as well as a TOPCon battery structure, thereby solving at least one technical problem mentioned in the background art.

[0007] (II) Technical Solution The technical solution adopted in this invention provides a method for preparing a high-density antireflection film using TOPCon battery tubular PECVD based on power optimization, the method comprising: Under a consistent process environment, gradient reaction power was set to determine the optimal power for silicon nitride and silicon oxynitride, respectively. Silicon nitride and silicon oxynitride films are deposited based on the optimal power combination.

[0008] Preferably, the silicon nitride reaction power is fixed, and the silicon oxynitride reaction power is set in a gradient to determine the optimal reaction power of silicon oxynitride.

[0009] Preferably, the reaction power of silicon oxynitride is fixed, and the reaction power of silicon nitride is set in a gradient to determine the optimal reaction power of silicon nitride.

[0010] Preferably, the optimal power is determined based on electrical performance parameters.

[0011] Preferably, when fixing the silicon nitride reaction power, the silicon oxynitride reaction power is set to 12KW, 13KW, 14KW and 15KW respectively.

[0012] Preferably, when fixing the silicon oxynitride reaction power, the silicon nitride reaction power is set to 15KW, 16KW, 17KW, 18KW and 19KW respectively.

[0013] Preferably, the silicon nitride deposition process is as follows: Pre-deposited Si x N y Layer: SiN4 gas and NH4 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach the set value and remain constant. The pre-deposition time is 10 seconds. Deposited Si x N y Layer 1: SiN4 gas and NH4 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 210 Pa and kept constant. A preset radio frequency power is applied to perform glow discharge on the silicon wafer inside the furnace tube. Deposited Si x N y 2nd layer: SiN4 gas and NH4 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 213 Pa and kept constant. The preset radio frequency power is introduced to perform glow discharge on the silicon wafer inside the furnace tube. Deposited Si x N y3rd layer: SiN4 gas and NH4 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 213 Pa and kept constant. The preset radio frequency power is introduced to perform glow discharge on the silicon wafer inside the furnace tube. Depositing SixNy 4 layers: SiN4 gas and NH4 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 213Pa and kept constant. A preset radio frequency power is applied to perform glow discharge on the silicon wafer inside the furnace tube. And deposited Si x N y 1 layer, deposited Si x N y 2 layers, deposited Si x N y The deposition time for the 3rd layer and the 4th layer of SixNy increases sequentially.

[0014] Preferably, the process of silicon oxynitride deposition is as follows: Pre-deposition of SiOxNy layer: SiN4 gas, NH4 gas and NO2 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 170 Pa and kept constant. The pre-deposition time is 10 seconds. Depositing SiOxNy 1 layer: SiN4 gas, NH4 gas and NO2 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 170 Pa and kept constant. A radio frequency power of 13KW is introduced to perform glow discharge on the silicon wafer inside the furnace tube. Depositing two SiOxNy layers: SiN4 gas, NH4 gas, and NO2 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 170 Pa and kept constant. A radio frequency power supply of 13KW is applied to perform glow discharge on the silicon wafer inside the furnace tube.

[0015] The second aspect provides a TOPCon battery, wherein the antireflective film of the TOPCon battery is prepared using any of the preparation methods described above.

[0016] (III) Beneficial Effects This invention provides a power-optimized method for preparing a high-density antireflection film using TOPCon battery tubular PECVD, which has the following advantages compared with existing technologies: By designing a stepped power experiment, the deposition power of each functional layer in the antireflection film was independently and systematically optimized. Ultimately, a specific power combination was adopted to maximize battery efficiency. This reduces light reflection from the silicon surface, increases light absorption, and enhances the passivation effect of the silicon nitride and silicon oxynitride films, resulting in a significant improvement in battery conversion efficiency. Specifically: By conducting stepped power experiments and using the final battery efficiency as the criterion, the optimal deposition power for the TOPCon structure was accurately determined, avoiding the blindness of traditional trial-and-error methods. By employing the specific power combination (SiOxNy:15kW, SiNx:H:18kW) discovered in this invention, a film with better density and passivation effect can be prepared, ultimately achieving a significant improvement in battery conversion efficiency (experiments have shown an absolute improvement of up to 0.05%). Without requiring changes to existing equipment, membrane structure, or the addition of new materials, only the power parameters of the equipment need to be optimized. It is easily integrated into existing mass production processes, making it highly practical and economical, and suitable for large-scale promotion. Attached Figure Description

[0017] Figure 1 The QE curve; Detailed Implementation To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. To address the technical problems raised in the background and the shortcomings of existing technologies, this invention proposes a method for systematically optimizing the deposition power of tubular PECVD through a stepped power experiment. This method aims to solve the problem that the density and passivation effect of the antireflection film on the front side of TOPCon batteries cannot be optimized simultaneously, thereby breaking through the efficiency bottleneck.

[0018] Specifically, a method for preparing high-density antireflection films using TOPCon battery tube PECVD based on power optimization is proposed. Different gradient reaction powers are set under a consistent process environment to verify the optimal power for silicon nitride and silicon oxynitride, respectively. Based on the optimal power combination, silicon nitride and silicon oxynitride films are deposited.

[0019] Specifically, the reaction power of silicon nitride is fixed, the reaction power of silicon oxynitride is set in a gradient, and the optimal reaction power of silicon oxynitride is determined.

[0020] Furthermore, by fixing the reaction power of silicon oxynitride and setting the reaction power of silicon nitride in a gradient manner, the optimal reaction power of silicon nitride is determined.

[0021] Specifically, the optimal power mentioned above is determined based on electrical performance parameters, that is, the optimal reaction power is selected based on the electrical performance parameters.

[0022] Specifically: S1: The graphite boat containing silicon wafers is fed into the furnace tube by a paddle rod. After the paddle rod is withdrawn, the furnace door is closed. S2: Turn on the auxiliary heating to preheat the furnace tubes and start vacuuming; S3: Leak detection, check whether the furnace tube leakage rate meets the process requirements; S4: After the leak detection meets the process requirements, the residual gas in the furnace tube is evacuated. S5: SiN4 and NH4 are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach the set value and remain constant to complete the pre-deposition; S6: Perform glow discharge on the silicon wafer using an RF power supply, with the RF power set to a fixed value; S7: A mixed gas of SiN4, NH4 and N2O is introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach a set value and remain constant. S8: Perform glow discharge on the silicon wafer using an RF power supply, and set the RF power in a gradient; conduct group experiments. S9: A mixture of SiN4 and N2O gas is introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach a set value and remain constant. S10: Perform glow discharge on the silicon wafer using an RF power supply; S11: After the glow discharge is completed, the furnace tube is evacuated; S12: Purge the furnace tubes with nitrogen gas; S13: After purging, evacuate the furnace tube; S14: Nitrogen purging to restore the pressure inside the furnace tube to normal atmospheric pressure; S15: Open the furnace door and use the paddle to remove the graphite boat from the furnace tube.

[0023] The electrical performance parameters of the batteries prepared under the corresponding gradients were detected respectively, and the optimal reaction power was selected, which is the optimal power for silicon oxynitride.

[0024] The core of the high-density antireflective film prepared by the above-mentioned PECVD process and equipment lies in the independent and systematic optimization of the deposition power of each functional layer in the antireflective film by designing a stepped power experiment. Finally, a specific power combination that makes the battery efficiency reach its peak can reduce light reflection on the silicon surface, increase the battery's absorption of light, improve the passivation effect of silicon nitride and silicon oxynitride films on the battery, and significantly improve the battery's conversion efficiency.

[0025] The following detailed explanation is provided with reference to specific embodiments: All the following embodiments use TOPCON N-type M10 A-grade solar cells, with a thickness of 130µm and a size of 182.2mm. The silicon wafer is 183.75mm thick. The front side of the wafer uses micro-conductive ALD, and the Naura front plating machine sequentially deposits alumina, silicon nitride, silicon oxynitride, and silicon oxide antireflective film. The back side uses Jiejiachuang alkaline polishing and polishing silicon wafers, and Jiejia Weichuang PE-POLY is used. The Naura back plating machine sequentially deposits silicon oxide, poly silicon, and silicon nitride.

[0026] Comparative example: S1: The graphite boat containing silicon wafers is fed into the furnace tube by a paddle rod. After the paddle rod is withdrawn, the furnace door is closed. S2: Turn on the auxiliary heating to preheat and raise the temperature of the furnace tube; S3: Leak Detection: Check whether the furnace tube leakage rate meets the process requirements; S4: Vacuuming: After the leak test meets the process requirements, the residual gas in the furnace tube is evacuated. S5: Pre-deposition of SixNy layer: SiN4 gas flow rate of 1300 sccm / min and NH4 gas flow rate of 5850 sccm / min are introduced into the furnace tube, while the pressure in the furnace tube is controlled to reach the set value and kept constant. The pre-deposition time is 10 seconds. S6: Deposition of SixNy 1 layer: SiN4 gas flow rate of 2930 sccm / min and NH4 gas flow rate of 10450 sccm / min are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 210 Pa and kept constant. 16KW of radio frequency power is introduced to perform glow discharge on the silicon wafer inside the furnace tube. The deposition time is 100 seconds. S7: Deposition of SixNy 2 layers: SiN4 gas flow rate of 2180 sccm / min and NH4 gas flow rate of 13570 sccm / min are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 213 Pa and kept constant. 16KW of radio frequency power is introduced to perform glow discharge on the silicon wafer inside the furnace tube. The deposition time is 108 seconds. S8: Deposition of SixNy 3 layers: SiN4 gas flow rate of 1800 sccm / min and NH4 gas flow rate of 15617 sccm / min are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 213 Pa and kept constant. 16KW of radio frequency power is introduced to perform glow discharge on the silicon wafer inside the furnace tube. The deposition time is 144 seconds. S9: Deposition of SixNy 4 layers: SiN4 gas flow rate of 1400 sccm / min and NH4 gas flow rate of 15617 sccm / min are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 213 Pa and kept constant. 16KW of radio frequency power is introduced to perform glow discharge on the silicon wafer inside the furnace tube. The deposition time is 270 seconds. S10: Vacuuming: Evacuate the residual gas inside the furnace tube; S11: Pre-deposition of SiOxNy layer: SiN4 gas flow rate of 1380 sccm / min, NH4 gas flow rate of 5980 sccm / min, and NO2 gas flow rate of 8510 sccm / min are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 170 Pa and kept constant, and the pre-deposition time is 10 seconds; S12: Deposition of SiOxNy 1 layer: SiN4 gas flow rate of 1380 sccm / min, NH4 gas flow rate of 5980 sccm / min, and NO2 gas flow rate of 8510 sccm / min are introduced into the furnace tube. At the same time, the pressure inside the furnace tube is controlled to reach 170 Pa and kept constant. 13KW of radio frequency power is introduced to perform glow discharge on the silicon wafer inside the furnace tube. The deposition time is 175 seconds. S13: Deposition of 2 SiOxNy layers: SiN4 gas flow rate of 1035 sccm / min, NH4 gas flow rate of 4600 sccm / min, and NO2 gas flow rate of 10235 sccm / min are introduced into the furnace tube. At the same time, the pressure inside the furnace tube is controlled to reach 170 Pa and kept constant. 13KW of radio frequency power is introduced to perform glow discharge on the silicon wafer inside the furnace tube. The deposition time is 215 seconds. S14: Vacuuming: Evacuate the residual gas inside the furnace tube; S15: Pre-deposition of SixOy layer: SiN4 gas flow rate of 1035 sccm / min and NO2 gas flow rate of 13455 sccm / min are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 160 Pa and kept constant, and the pre-deposition time is 10 seconds; S15: Deposition of SixOy layer: SiN4 gas flow rate of 1035 sccm / min and NO2 gas flow rate of 13455 sccm / min are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 160 Pa and kept constant. The silicon wafer inside the furnace tube is subjected to glow discharge through a 13KW radio frequency power supply, and the deposition time is 90 seconds. S16: Vacuuming: Evacuate the residual gas inside the furnace tube; S17: Purge the furnace tubes with nitrogen; S18: After purging, the furnace tube is evacuated; S19: Nitrogen is added to restore the pressure inside the furnace tube to normal atmospheric pressure; S20: Open the furnace door and use the paddle to remove the graphite boat from the furnace tube.

[0027] The above comparative example is used as a fixed reaction power.

[0028] The RF power supply power in the silicon nitride S6-S9 steps of the comparative example was verified in a gradient of 15KW-19KW; the RF power supply power in the silicon oxynitride S12-S13 steps of the comparative example was verified in a gradient of 12KW-15KW; the two preferred schemes were then superimposed for verification. The electrical performance data of the example and the comparative example were compared using the national standard method as shown in the table below: Table 1 Comparison of power gradient electrical performance parameters of silicon nitride RF power supply under a fixed silicon oxynitride RF power of 13KW By comparing the above electrical performance data, it can be seen that Example 3 has better electrical performance for 18KW. Table 2 Comparison of power gradient electrical performance parameters of silicon oxynitride RF power supply under a fixed silicon oxynitride RF power of 16KW. By comparing the above electrical performance data, it can be seen that Example 7 has better electrical performance for 15KW. The electrical performance parameters were verified by superimposing the silicon nitride reaction power of 18KW and the silicon oxynitride reaction power of 15KW: Table 3 Comparison of electrical performance parameters between the examples and the comparative examples. The comparison of the above electrical performance data shows that the embodiment has better electrical performance data. Through power gradient verification with silicon nitride thin film, the embodiment of the present invention achieves optimal efficiency at 18 kW, with an efficiency improvement of 0.040%; power gradient verification with silicon oxynitride thin film shows optimal efficiency at 15 kW, with an efficiency improvement of 0.028%; the combined efficiency of the two can improve the overall efficiency by 0.067%.

[0029] like Figure 1 As shown, the superimposed power band spectral responses of the two groups are significantly better than the band spectral responses of the two groups alone and the control group. Table 4 PID Data The power verification showed that the PID96 attenuation was satisfactory and basically the same as the control group. Conclusion: Through the above-described stepped experiments, the optimal power combination for this specific production line and TOPCon battery structure was determined to be: SiOxNy 15kW + SiNx:H 18kW. Updating this parameter combination to the mass production process specifications improves the anti-reflection effect of the positive film, increases light absorption, and enhances short-circuit current and open-circuit voltage while ensuring performance degradation, thus stably improving the average battery efficiency. This invention only involves changes to the process formulation and does not involve changes to equipment or external power conditions; it is fully compatible with existing production lines and incurs no additional modification costs.

Claims

1. A method for preparing a high-density antireflective film using TOPCon battery tubular PECVD based on power optimization, characterized in that, The method includes: Under a consistent process environment, gradient reaction power was set to determine the optimal power for silicon nitride and silicon oxynitride, respectively. Silicon nitride and silicon oxynitride films are deposited based on the optimal power combination.

2. The method for preparing a high-density antireflective film using TOPCon battery tubular PECVD based on power optimization according to claim 1, characterized in that, By fixing the silicon nitride reaction power and setting the silicon oxynitride reaction power in a gradient manner, the optimal reaction power for silicon oxynitride is determined.

3. The method for preparing a high-density antireflective film using TOPCon battery tubular PECVD based on power optimization according to claim 1, characterized in that, By fixing the reaction power of silicon oxynitride and setting the reaction power of silicon nitride in a gradient manner, the optimal reaction power of silicon nitride is determined.

4. The method for preparing a high-density antireflective film using TOPCon battery tubular PECVD based on power optimization according to claim 1, characterized in that, The optimal power is determined based on electrical performance parameters.

5. The method for preparing a high-density antireflective film using TOPCon battery tubular PECVD based on power optimization according to claim 2, characterized in that, When the silicon nitride reaction power is fixed, the silicon oxynitride reaction power is set to 12KW, 13KW, 14KW and 15KW respectively.

6. The method for preparing a high-density antireflective film using TOPCon battery tubular PECVD based on power optimization according to claim 3, characterized in that, When the reaction power of silicon oxynitride is fixed, the reaction power of silicon nitride is set to 15KW, 16KW, 17KW, 18KW and 19KW respectively.

7. The method for preparing a high-density antireflective film using TOPCon battery tubular PECVD based on power optimization according to claim 1, characterized in that, The silicon nitride deposition process is as follows: Pre-deposited Si x N y Layer: SiN4 gas and NH4 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach the set value and remain constant. The pre-deposition time is 10 seconds. Deposited Si x N y Layer 1: SiN4 gas and NH4 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 210 Pa and kept constant. A preset radio frequency power is applied to perform glow discharge on the silicon wafer inside the furnace tube. Deposited Si x N y 2nd layer: SiN4 gas and NH4 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 213 Pa and kept constant. The preset radio frequency power is introduced to perform glow discharge on the silicon wafer inside the furnace tube. Deposited Si x N y 3rd layer: SiN4 gas and NH4 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 213 Pa and kept constant. The preset radio frequency power is introduced to perform glow discharge on the silicon wafer inside the furnace tube. Depositing SixNy 4 layers: SiN4 gas and NH4 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 213 Pa and kept constant. A preset radio frequency power is applied to perform glow discharge on the silicon wafer inside the furnace tube. And deposited Si x N y 1 layer, deposited Si x N y 2 layers, deposited Si x N y The deposition time for the 3rd layer and the 4th layer of SixNy increases sequentially.

8. The method for preparing a high-density antireflective film using TOPCon battery tubular PECVD based on power optimization according to claim 1, characterized in that, The process of silicon oxynitride deposition is as follows: Pre-deposition of SiOxNy layer: SiN4 gas, NH4 gas and NO2 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 170 Pa and kept constant, and the pre-deposition time is 10 seconds; Depositing SiOxNy 1 layer: SiN4 gas, NH4 gas and NO2 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 170 Pa and kept constant. A radio frequency power of 13KW is introduced to perform glow discharge on the silicon wafer inside the furnace tube. Depositing two SiOxNy layers: SiN4 gas, NH4 gas, and NO2 gas are introduced into the furnace tube, while the pressure inside the furnace tube is controlled to reach 170 Pa and kept constant. A radio frequency power supply of 13KW is applied to perform glow discharge on the silicon wafer inside the furnace tube.

9. A TOPCon battery, wherein the antireflective coating of the TOPCon battery is prepared by any one of the preparation methods described in claims 1-8.

Images