Preparation method of laminated anti-reflection film on front side of TOPCon battery

Abstract

The invention relates to a preparation method of a front laminated anti-reflection film of a TOPCon cell, and belongs to the technical field of solar cell preparation. Comprising the following steps: feeding into a boat, preheating and vacuumizing; carrying out leak detection and vacuumizing; pre-depositing ammonia gas; carrying out glow discharge; vacuumizing is conducted; pre-depositing silane and ammonia gas; depositing a first silicon nitride film layer; depositing a second silicon nitride film layer; depositing a third silicon nitride film layer; depositing a fourth silicon nitride film layer; and vacuumizing, purging the furnace tube, and discharging after the air pressure is recovered. The laminated pure silicon nitride anti-reflection film can be formed on the front surface of the TOPCon battery, so that a good anti-reflection effect is achieved, the surface of a silicon wafer can be passivated, and the performance of the battery is improved. And meanwhile, the silicon nitride film layer has better compactness, so that the PID and UV attenuation resistance of the battery piece can be remarkably improved. In addition, consumption of laughing gas (N2O) can be omitted in the process, so that tail gas treatment equipment for tail exhaust laughing gas is omitted, and the production cost can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell preparation, and particularly to a method for preparing an antireflection film for the front stack of a TOPCon cell. Background Art

[0002] The TOPCon cell, fully known as Tunnel Oxide Passivated Contact cell, is a solar cell based on the principle of selective carriers and tunneling oxide passivated contact. In recent years, due to its obvious advantages such as high conversion efficiency, low attenuation performance, and high cost performance, it has been gradually adopted by industry enterprises. Its cell structure is an N-type silicon substrate cell. An ultrathin silicon oxide is prepared on the back of the cell, and then a doped silicon thin layer is deposited. The two together form a passivated contact structure, effectively reducing surface recombination and metal contact recombination. Due to the excellent carrier selective passivated contact performance, the theoretical limit efficiency of the TOPCon cell is as high as 28.7%, which is the technology closest to the theoretical limit efficiency of crystalline silicon solar cells (29.43%) and has great R & D potential.

[0003] Currently, the front antireflection film layer of TOPCon cells is mainly prepared by the PECVD process (plasma enhanced chemical vapor deposition method). Specifically, reaction gases such as silane (SiH4), ammonia (NH3), and nitrous oxide (N2O) are introduced into the reaction chamber, and are ionized to form plasma under the action of an electric field. The high-energy electrons in the plasma collide with the reaction gas molecules, causing them to be excited, dissociated, or ionized, thereby generating the active groups required for the reaction. These active groups undergo chemical reactions on the silicon wafer surface to form a silicon nitride & silicon oxynitride & silicon oxide film layer. This solution has mature technology, simple control, good coating uniformity, high film density, and good cell efficiency. It is the most mature technical route currently and has achieved mass production.

[0004] However, the silicon oxynitride film layer may undergo chemical changes under the influence of environmental factors such as long-term light, temperature, and humidity, resulting in performance degradation, which will affect the long-term stability and service life of the cell. At the same time, the silicon oxynitride process of TOPCon cells needs to be connected with subsequent cell manufacturing steps (such as component encapsulation, etc.). Due to the incompatibility of the film layer performance and structure with the component glass, it will lead to a decrease in cell performance and component power loss. In addition, during the silicon oxynitride process of TOPCon cells, some harmful gases (such as N2O, etc.) may be generated, and these gases need to be properly treated to avoid environmental pollution, increasing the production cost. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a method for preparing an antireflection film for the front stack of a TOPCon cell. The technical solution of the present invention is as follows:

[0006] A preparation method of an antireflection film for the front stack of a TOPCon battery, which includes:

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

[0008] S2, Leak detection and evacuation;

[0009] S3, Ammonia pre-deposition;

[0010] S4, Glow discharge;

[0011] S5, Evacuation;

[0012] S6, Pre-deposition of silane and ammonia;

[0013] S7, Depositing the first silicon nitride film layer: Glow discharge the silicon wafer through a radio frequency power supply to form the first silicon nitride film layer, where the silane flow rate is 2930 ± 2000 sccm, the ammonia flow rate is 10450 ± 3000 sccm, the pressure is 205 ± 30 Pa, the temperature is maintained at 485 ± 30 °C, the power is 11 ± 3 KW, the pulse on / off is 5 ± 1 / 75 ± 25 ms, and the duration is 102 ± 20 s;

[0014] S8, Depositing the second silicon nitride film layer: Glow discharge the silicon wafer through a radio frequency power supply to form the second silicon nitride film layer, where the silane flow rate is 2180 ± 1000 sccm, the ammonia flow rate is 13570 ± 3000 sccm, the pressure is 225 ± 30 Pa, the temperature is maintained at 485 ± 30 °C, the power is 11 ± 3 KW, the pulse on / off is 5 ± 1 / 75 ± 25 ms, and the duration is 207 ± 20 s;

[0015] S9, Depositing the third silicon nitride film layer: Glow discharge the silicon wafer through a radio frequency power supply to form the third silicon nitride film layer, where the silane flow rate is 1800 ± 500 sccm, the ammonia flow rate is 15617 ± 3000 sccm, the pressure is 225 ± 30 Pa, the temperature is maintained at 485 ± 30 °C, the power is 11 ± 3 KW, the pulse on / off is 5 ± 1 / 75 ± 25 ms, and the duration is 268 ± 20 s;

[0016] S10, Depositing the fourth silicon nitride film layer: Glow discharge the silicon wafer through a radio frequency power supply to form the fourth silicon nitride film layer, where the silane flow rate is 1310 ± 500 sccm, the ammonia flow rate is 13570 ± 3000 sccm, the pressure is 225 ± 30 Pa, the temperature is maintained at 485 ± 30 °C, the power is 11 ± 3 KW, the pulse on / off is 5 ± 1 / 75 ± 25 ms, and the duration is 325 ± 20 s;

[0017] S11, Evacuation, purging the furnace tube, restoring the air pressure and then unloading the boat.

[0018] Optionally, the boat feeding, preheating and vacuum pumping in S1 include:

[0019] Feed the graphite boat loaded with silicon wafers into the furnace tube through a silicon carbide slurry rod. After the rod withdraws, close the furnace door, turn on the auxiliary heating to preheat the furnace tube. The preheating temperature is 485 ± 30 °C. At the same time, start vacuum pumping to the low pressure.

[0020] Optionally, the leak detection and vacuum pumping in S2 include:

[0021] After the preheating is completed, start leak detection to check whether the leak rate of the furnace tube meets the process requirements. After the leak detection meets the process requirements, evacuate the residual gas in the furnace tube.

[0022] Optionally, the ammonia pre-deposition in S3 includes:

[0023] Introduce ammonia into the furnace tube. The ammonia flow rate is 10450 ± 3000 sccm, the pressure in the furnace tube is 205 ± 30 Pa, the temperature is 485 ± 30 °C, and the duration is 20 ± 10 s to complete the ammonia pre-deposition.

[0024] Optionally, the glow discharge in S4 includes:

[0025] After the ammonia pre-deposition, the silicon wafers are subjected to glow discharge through a radio frequency power supply to ionize ammonia to form plasma. Among them, the ammonia flow rate is 10450 ± 3000 sccm, the pressure is 205 ± 30 Pa, the power is 11 ± 3 KW, the pulse on / off is 5 ± 1 / 75 ± 25 ms, the temperature is maintained at 485 ± 30 °C, and the duration is 30 ± 10 s.

[0026] Optionally, the pre-deposition of silane and ammonia in S6 includes:

[0027] Introduce a mixed gas of silane and ammonia into the furnace tube. The silane flow rate is 2930 ± 2000 sccm, the ammonia flow rate is 10450 ± 3000 sccm, the pressure in the furnace tube is 205 ± 30 Pa, and the duration is 20 ± 10 s to complete the pre-deposition of silane and ammonia.

[0028] Optionally, the vacuum pumping, furnace tube purging, and boat unloading after restoring the air pressure in S11 include:

[0029] After the glow discharge is completed, evacuate the furnace tube; use nitrogen to purge the furnace tube. The nitrogen flow rate is 20000 ± 5000 sccm, and the duration is 20 ± 10 s; after the purging is completed, restore the pressure in the furnace tube to normal atmospheric pressure; open the furnace door, extend the rod and take out the graphite boat from the furnace tube.

[0030] Optionally, the thickness of the first silicon nitride film layer is 10 ± 3 nm, the thickness of the second silicon nitride film layer is 13 ± 3 nm, the thickness of the third silicon nitride film layer is 20 ± 5 nm, and the thickness of the fourth silicon nitride film layer is 28 ± 5 nm.

[0031] All of the above optional technical solutions can be arbitrarily combined, and the present invention does not elaborate on the structures after combination one by one.

[0032] With the above solutions, the beneficial effects of the present invention are as follows:

[0033] By setting the deposition process of four silicon nitride film layers, a stacked pure silicon nitride antireflection film can be formed on the front side of the TOPCon cell. By controlling the reaction conditions of each silicon nitride film layer, the antireflection film is formed by stacking multiple silicon nitride film layers with different thicknesses and refractive indices, so that the reflections of light between different layers interfere with each other, thereby reducing the degree of reflection. By controlling the reaction conditions of each thin film layer to control the thickness and refractive index, the reflections of light with a specific wavelength in the multi-layer film can cancel each other out in terms of phase, thereby achieving the antireflection effect. This antireflection film not only has a good antireflection effect, but also can passivate the surface of the silicon wafer to improve the performance of the cell. At the same time, because the silicon nitride film layer has better densification, it can significantly improve the anti-PID and UV attenuation performance of the cell. In addition, this process can also eliminate the consumption of nitrous oxide (N2O), and then eliminate the tail gas treatment equipment for tail gas nitrous oxide, thereby reducing production costs. In addition, the pure silicon nitride film layer is more compatible with the existing component glass, which can effectively reduce the component packaging loss, improve the component power level, improve the stability of the cell, and enhance the component-end power level.

[0034] The above description is only an overview of the technical solutions of the present invention. In order to be able to understand the technical means of the present invention more clearly and implement it in accordance with 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. Description of the Drawings

[0035] Figure 1 is a flowchart of the method provided by the embodiment of the present invention.

[0036] Figure 2 is a schematic diagram of the composition structure of the stacked antireflection film on the front side of the TOPCon cell prepared by the embodiment of the present invention.

[0037] Figure 3 is a schematic diagram of the composition structure of the stacked antireflection film on the front side of the TOPCon cell prepared by the comparative example. Detailed Embodiments

[0038] 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.

[0039] As Figure 1 shown, the preparation method of the front stack antireflection film of the TOPCon battery provided by the embodiment of the present invention is based on the PECVD method to prepare a silicon nitride film layer, including:

[0040] S1, Load the boat, preheat and evacuate.

[0041] In a specific embodiment, the loading the boat, preheating and evacuating in S1 includes: sending the graphite boat loaded with silicon wafers into the furnace tube through a silicon carbide slurry rod, closing the furnace door after the rod exits, turning on auxiliary heating for furnace tube preheating, the preheating temperature is 485 ± 30 °C, and at the same time start evacuating to a low pressure (100 mbar).

[0042] S2, Leak detection and evacuation.

[0043] In a specific embodiment, the leak detection and evacuation in S2 includes: after the preheating is completed, start leak detection, check whether the leak rate of the furnace tube meets the process requirements, and evacuate the residual gas in the furnace tube after the leak detection meets the process requirements. Specifically, when the leak rate of the furnace tube ≤ 30 mtorr / min, it is determined that the leak rate of the furnace tube meets the process requirements.

[0044] S3, Ammonia pre-deposition.

[0045] In a specific embodiment, the ammonia pre-deposition in S3 includes: introducing ammonia into the furnace tube, the ammonia flow rate is 10450 ± 3000 sccm, the pressure in the furnace tube is 205 ± 30 Pa, the temperature is 485 ± 30 °C, and the duration is 20 ± 10 s to complete the ammonia pre-deposition.

[0046] By introducing ammonia for ammonia pre-deposition, more hydrogen ions and saturated dangling bonds can be formed on the surface of the silicon wafer, improving the passivation performance.

[0047] S4, Glow discharge.

[0048] In a specific embodiment, the glow discharge in S4 includes: after the ammonia pre-deposition, the silicon wafer is subjected to glow discharge through a radio frequency power supply, ionizing ammonia to form a plasma, exciting, dissociating or ionizing it to form a large number of hydrogen ions, where the ammonia flow rate is 10450 ± 3000 sccm, the pressure is 205 ± 30 Pa, the power is 11 ± 3 KW, the pulse on / off is 5 ± 1 / 75 ± 25 ms, the temperature is maintained at 485 ± 30 °C, and the duration is 30 ± 10 s. Among them, the pulse on / off of 5 ± 1 / 75 ± 25 ms means that after the pulse is on for 5 ± 1 ms, it is off for 75 ± 25 ms, and then on for 5 ± 1 ms, and so on in a cycle.

[0049] S5, Evacuate.

[0050] Specifically, after the glow discharge is completed, the furnace tube is evacuated.

[0051] S6, Pre-deposit silane and ammonia.

[0052] In a specific embodiment, the pre-deposited silane and ammonia in S6 include: introducing a mixed gas of silane and ammonia into the furnace tube, with the silane flow rate being 2930 ± 2000 sccm, the ammonia flow rate being 10450 ± 3000 sccm, the pressure in the furnace tube being 205 ± 30 Pa, and the duration being 20 ± 10 s to complete the pre-deposition of silane and ammonia.

[0053] In this step, at the early stage of introducing the reaction gas, the reaction gas is filled in, but the RF power supply is not turned on, so that the reaction gas can uniformly fill the entire furnace tube, combined with the film layer stacking process, in order to make the film layer structure formed subsequently more uniform.

[0054] S7, Deposit the first silicon nitride film layer: Glow discharge the silicon wafer through an RF power supply to form the first silicon nitride film layer, where the silane flow rate is 2930 ± 2000 sccm, the ammonia flow rate is 10450 ± 3000 sccm, the pressure is 205 ± 30 Pa, the temperature is maintained at 485 ± 30 °C, the power is 11 ± 3 KW, the pulse on / off is 5 ± 1 / 75 ± 25 ms, and the duration is 102 ± 20 s.

[0055] S8, Deposit the second silicon nitride film layer: Glow discharge the silicon wafer through an RF power supply to form the second silicon nitride film layer, where the silane flow rate is 2180 ± 1000 sccm, the ammonia flow rate is 13570 ± 3000 sccm, the pressure is 225 ± 30 Pa, the temperature is maintained at 485 ± 30 °C, the power is 11 ± 3 KW, the pulse on / off is 5 ± 1 / 75 ± 25 ms, and the duration is 207 ± 20 s.

[0056] S9, Deposit the third silicon nitride film layer: Glow discharge the silicon wafer through an RF power supply to form the third silicon nitride film layer, where the silane flow rate is 1800 ± 500 sccm, the ammonia flow rate is 15617 ± 3000 sccm, the pressure is 225 ± 30 Pa, the temperature is maintained at 485 ± 30 °C, the power is 11 ± 3 KW, the pulse on / off is 5 ± 1 / 75 ± 25 ms, and the duration is 268 ± 20 s;

[0057] S10, Deposit the fourth silicon nitride film layer: Glow discharge the silicon wafer through an RF power supply to form the fourth silicon nitride film layer, where the silane flow rate is 1310 ± 500 sccm, the ammonia flow rate is 13570 ± 3000 sccm, the pressure is 225 ± 30 Pa, the temperature is maintained at 485 ± 30 °C, the power is 11 ± 3 KW, the pulse on / off is 5 ± 1 / 75 ± 25 ms, and the duration is 325 ± 20 s.

[0058] S11, evacuate the vacuum, purge the furnace tubes, and take out the boat after restoring the air pressure.

[0059] In a specific embodiment, the steps of evacuating the vacuum, purging the furnace tubes, and taking out the boat after restoring the air pressure in S11 include: after glow discharge is completed, evacuate the vacuum of the furnace tubes; use nitrogen to purge the furnace tubes, with a nitrogen flow rate of 20000 ± 5000 sccm and a duration of 20 ± 10 s; after purging is completed, restore the pressure inside the furnace tubes to normal atmospheric pressure; open the furnace door, extend the paddle rod in, and take out the graphite boat from the furnace tubes.

[0060] In the front stack antireflection film of the TOPCon cell formed by the above process, the thickness of the first silicon nitride film layer is 10 ± 3 nm, the thickness of the second silicon nitride film layer is 13 ± 3 nm, the thickness of the third silicon nitride film layer is 20 ± 5 nm, and the thickness of the fourth silicon nitride film layer is 28 ± 5 nm.

[0061] It should be noted that the data before "±" in the embodiments of the present invention are the preferred data in the embodiments of the present invention. Based on the preferred data, the preparation of the front stack pure silicon nitride antireflection film of the TOPCon cell can obtain better effects.

[0062] By adopting the above preparation method, a stacked pure silicon nitride antireflection film can be formed on the front of the TOPCon cell. By controlling the reaction conditions of each silicon nitride film layer, the antireflection film is formed by stacking multiple silicon nitride film layers with different thicknesses and refractive indices, so that the reflection of light between different layers interferes with each other, thereby reducing the degree of reflection. By controlling the thickness and refractive index of each thin film layer, the reflection of light with a specific wavelength in the multi-layer film can be made to cancel each other out in phase, thereby achieving the antireflection effect. This antireflection film not only has a good antireflection effect, but also can passivate the surface of the silicon wafer and improve the performance of the cell. At the same time, because the silicon nitride film layer has better densification, it can significantly improve the anti-PID and UV attenuation performance of the cell. In addition, this process can also eliminate the consumption of nitrous oxide (N2O), and then eliminate the tail gas treatment equipment for tail gas nitrous oxide, thereby reducing production costs. In addition, the pure silicon nitride film layer is more compatible with the existing component glass, which can effectively reduce the component packaging loss and improve the component power level.

[0063] To verify the beneficial effects of the method provided in the embodiments of the present invention, the following embodiments provide a method for preparing a TOPCon cell.

[0064] Embodiment: The method for preparing a TOPCon cell provided in this embodiment includes:

[0065] (1) Select an N-type monocrystalline silicon wafer with a size of 210.0 * 210.0 mm and a thickness in the range of 130 ± 20 μm; clean and texture the silicon wafer to remove the loss layer and impurities on the silicon wafer itself, forming a textured surface layer, where the thinning amount during cleaning and texturing is controlled between 0.34 - 0.50 g.

[0066] (2) Place the silicon wafer with the above-mentioned texture into a diffusion equipment for boron diffusion to form a PN junction, and the surface sheet resistance range is between 165 - 205 ohm / sq.

[0067] (3) Perform laser propulsion on the surface of the PN junction layer of the above-mentioned diffused silicon wafer, and the sheet resistance range of the propelled area is between 115 ± 15 ohm / sq.

[0068] (4) Perform a thermal oxidation process on the above-mentioned silicon wafer after SE. Through high temperature (1040 ± 10 °C), the junction depth is further advanced; through oxidation segregation, the surface doping concentration is reduced, and the boron-rich layer is reduced; the micro-damage caused by laser engraving is repaired; through oxidation gettering, the bulk defects are reduced; after oxidation, the surface sheet resistance range is between 330 - 410 ohm / sq.

[0069] (5) For the above-mentioned silicon wafer after thermal oxidation treatment, use a chain-type BSG removal machine to remove the boron-silicate glass around the edge and back of the silicon wafer, and then use a tank-type machine tool with additives to combine with the boron-silicate glass on the surface of the silicon wafer, which can effectively prevent the reaction between alkali and the silicon wafer, complete the back etching and polishing, improve the back reflectivity, increase the long-wave absorption of the cell, make the surface smoother, reduce the surface dangling bonds, reduce the surface recombination, and improve the efficiency. After the process is completed, it is necessary to ensure that the edge hydrophobicity reaches the standard of no diffusion for 5 seconds, the thinning amount is controlled between 0.185 - 0.285 g, the back reflectivity is controlled between 34 - 38%, and the base size of the tower is controlled between 8 - 12 μm.

[0070] (6) Perform a PE-poly process on the above-mentioned silicon wafer after alkali polishing to form a back tunneling oxide layer and a heavily doped silicon thin film stacked passivation contact, and the film thickness after Poly is controlled between 79 - 103 nm.

[0071] (7) Anneal the above-mentioned silicon wafer after PE-poly. At high temperature (800 - 950 °C), introduce nitrogen as a protective gas, and through the processes of heating, constant temperature, and cooling, convert the amorphous silicon grown by PECVD into polycrystalline silicon, activate the phosphorus atoms in the thin film deposited by the poly process to form effective doping, and at the same time form a pinhole tunneling layer to improve the passivation effect. The sheet resistance range after annealing is controlled between 30 - 70 ohm / sq.

[0072] (8) Perform RCA cleaning on the silicon wafers after the above annealing treatment. Remove the PSG on the front and side surfaces through a chain machine, and remove the oxide layer on the surface of the boron-diffused poly-silicon. It is necessary to ensure that the edge hydrophobicity reaches the standard of no diffusion within 5 seconds. The batch machine is used to remove the boron-diffused poly-silicon with plating around, and the hydrofluoric acid bath is used to remove the PSG and BSG. After the process is completed, the weight removal is controlled within 0.009 - 0.017 g.

[0073] (9) Perform ALD process on the front surface of the silicon wafers after the above RCA cleaning, that is, the boron-diffused surface, to deposit an Al2O3 thin film. Utilize the negative charge characteristic of Al2O3 to generate an interfacial electric field pointing into the silicon wafer at the Al2O3 / Si interface, reduce the interfacial recombination rate, and improve the minority carrier lifetime. The film thickness after ALD is controlled within 2.3 - 3.5 nm.

[0074] (10) Perform front and back surface PECVD coating on the single crystal wafers after the above ALD is completed. Use low-temperature plasma as the energy source. Place the silicon wafers on the cathode of the glow discharge under low pressure. Utilize the glow discharge to heat the silicon wafers to a predetermined temperature, and then introduce an appropriate amount of SiH4 and NH3. Through a series of chemical reactions and plasma reactions, a solid film (SiNx) is formed on the surface of the sample. The thickness control range of the front surface anti-reflection film is 57 - 83 nm, the refractive index is 2.11 - 2.31, and the thickness control range of the back surface anti-reflection film is 67 - 93 nm, the refractive index is 1.95 - 2.15. Among them, the front surface anti-reflection film is prepared by the method provided in the embodiments of the present invention, and the results are as Figure 2 shown.

[0075] (11) Perform screen printing and sintering on the silicon wafers with the front and back surfaces coated with the film above to form metal electrodes. Among them, the single consumption of the back surface main grid silver paste is 0.0065 - 0.0105 g / pcs, the single consumption of the back surface fine grid silver paste is 0.036 - 0.052 g / pcs, the single consumption of the front surface main grid silver paste is 0.007 - 0.011 g / pcs, and the single consumption of the front surface fine grid silver paste is 0.032 - 0.048 g / pcs.

[0076] (12) Perform light injection treatment on the battery wafers after the above sintering to complete the preparation of the TOPCon battery.

[0077] Compare the TOPCon battery prepared by the above embodiments with the TOPCon battery prepared by the existing process (comparative example). Among them, the front surface anti-reflection film in the comparative example is a silicon nitride & silicon oxynitride & silicon oxide front surface laminated anti-reflection film layer, and its structure is as Figure 3 shown. The comparison results are shown in the battery electrical performance table in Table 1, the module power table in Table 2, and the reliability test result table in Table 3.

[0078] Table 1

[0079] Group Eta / % Uoc / V Isc / A FF / % Rs / Ω Rsh / Ω IRev2 / A Example 26.288 0.7303 17.99 88.23 0.0014 1410 0.051 Comparative Example 26.397 0.7299 18.102 88.1 0.0017 1408 0.048 Difference -0.109 0.0004 -0.112 0.13 -0.0004 2 0.003

[0080] Table 2

[0081] Group Module Power W / piece Module CTM Example 714.99 97.10％ Comparative Example 708.47 96.22％ Difference 6.52 0.88％

[0082] Table 3

[0083] Group PID288 Attenuation UV60 Attenuation Example 1.27％ 0.36％ Comparative Example 1.97％ 1.07％ Difference -0.7％ -0.71％

[0084] As can be seen from Table 1 to Table 3, compared with the comparative examples, the TOPCon cells prepared in the embodiments of the present invention have a battery electrical performance 0.1% lower, mainly due to a 110 mA lower Isc. However, the power of the module is 6.52 W / block higher, and the CTM of the module is 0.88% higher. The power advantage of the module is much greater than the efficiency loss at the cell end, and there is an obvious advantage in the module output. At the same time, the cell wafers prepared in the embodiments of the present invention have better battery stability and anti-attenuation performance, and both the PID288 and UV60 attenuations are significantly improved and reduced.

[0085] The above description is only a preferred embodiment of the present invention and is not intended 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 method for preparing a front-side laminated anti-reflection film for a TOPCon cell, characterized in that: include: S1, enter the boat, preheat and evacuate; S2, leak detection and vacuuming; S3, ammonia pre-deposition; S4, glow discharge; S5, vacuuming; S6, pre-deposition of silane and ammonia; S7, depositing a first silicon nitride film layer: performing glow discharge on the silicon wafer through a radio frequency power supply to form a first silicon nitride film layer, wherein the silane flow rate is 2930±2000sccm, the ammonia flow rate is 10450±3000sccm, the pressure is 205±30Pa, the temperature is maintained at 485±30°C, the power is 11±3KW, the pulse on / off is 5±1 / 75±25ms, and the duration is 102±20s; S8, depositing a second silicon nitride film layer: performing glow discharge on the silicon wafer through a radio frequency power supply to form a second silicon nitride film layer, wherein the silane flow rate is 2180±1000sccm, the ammonia flow rate is 13570±3000sccm, the pressure is 225±30Pa, the temperature is maintained at 485±30°C, the power is 11±3KW, the pulse on / off is 5±1 / 75±25ms, and the duration is 207±20s; S9, depositing a third silicon nitride film layer: performing glow discharge on the silicon wafer through a radio frequency power supply to form a third silicon nitride film layer, wherein the silane flow rate is 1800±500sccm, the ammonia flow rate is 15617±3000sccm, the pressure is 225±30Pa, the temperature is maintained at 485±30°C, the power is 11±3KW, the pulse on / off is 5±1 / 75±25ms, and the duration is 268±20s; S10, depositing a fourth silicon nitride film layer: performing glow discharge on the silicon wafer through a radio frequency power supply to form a fourth silicon nitride film layer, wherein the silane flow rate is 1310±500sccm, the ammonia flow rate is 13570±3000sccm, the pressure is 225±30Pa, the temperature is maintained at 485±30°C, the power is 11±3KW, the pulse on / off is 5±1 / 75±25ms, and the duration is 325±20s; S11, evacuate the vacuum, purge the furnace tube, restore the air pressure and then exit the boat.

2. The method for preparing the front-side laminated anti-reflection film of TOPCon battery according to claim 1, characterized in that: Said step of loading the boat, preheating and evacuating the boat in S1 includes: The graphite boat with silicon wafers is sent into the furnace tube through the silicon carbide paddle rod. After the paddle rod is withdrawn, the furnace door is closed and the auxiliary heating is turned on to preheat the furnace tube. The preheating temperature is 485±30℃, and vacuum is started to the bottom pressure at the same time.

3. The method for preparing the front-side laminated anti-reflection film of TOPCon battery according to claim 1, characterized in that: The leak detection and vacuuming in S2 include: After preheating, start leak detection to check whether the leakage rate of the furnace tube meets the process requirements. After the leak detection meets the process requirements, the residual gas in the furnace tube is evacuated.

4. The method for preparing the front-side laminated anti-reflection film of TOPCon battery according to claim 1, characterized in that: The ammonia pre-deposition in S3 includes: Ammonia gas was introduced into the furnace tube with a flow rate of 10450±3000sccm, a pressure of 205±30Pa, a temperature of 485±30°C, and a duration of 20±10s to complete ammonia pre-deposition.

5. The method for preparing the front-side laminated anti-reflection film of TOPCon battery according to claim 1, characterized in that: The glow discharge in S4 includes: After the ammonia pre-deposition, the silicon wafer is glow discharged by a radio frequency power supply to ionize the ammonia to form plasma, wherein the ammonia flow rate is 10450±3000sccm, the pressure is 205±30Pa, the power is 11±3KW, the pulse on / off is 5±1 / 75±25ms, the temperature is maintained at 485±30°C, and the duration is 30±10s.

6. The method for preparing the front-side laminated anti-reflection film of TOPCon battery according to claim 1, characterized in that: The pre-deposition of silane and ammonia in S6 includes: A mixed gas of silane and ammonia is introduced into the furnace tube, with a silane flow rate of 2930±2000sccm, an ammonia flow rate of 10450±3000sccm, a pressure in the furnace tube of 205±30Pa, and a duration of 20±10s to complete the pre-deposition of silane and ammonia.

7. The method for preparing the front-side laminated anti-reflection film of TOPCon battery according to claim 1, characterized in that: The step of evacuating the vacuum, purging the furnace tube, restoring the gas pressure and then exiting the boat in S11 includes: After the glow discharge is completed, the furnace tube is evacuated; the furnace tube is purged with nitrogen with a nitrogen flow rate of 20000±5000sccm for 20±10s; after the purging is completed, the pressure in the furnace tube is restored to normal atmospheric pressure; the furnace door is opened, the paddle rod is inserted and the graphite boat is taken out of the furnace tube.

8. The method for preparing the front-side laminated anti-reflection film of TOPCon battery according to claim 1, characterized in that: The thickness of the first silicon nitride film layer is 10±3 nm, the thickness of the second silicon nitride film layer is 13±3 nm, the thickness of the third silicon nitride film layer is 20±5 nm, and the thickness of the fourth silicon nitride film layer is 28±5 nm.

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