Preparation method of crystalline silicon double-sided multi-layer passivation film

Abstract

The invention relates to the technical field of photovoltaic equipment, in particular to a preparation method of a crystalline silicon double-sided multi-layer passivation film. The preparation method comprises the following steps: pretreating the substrate stainless steel sheet; preparing a multi-layer composite film; treating the multi-layer composite film; preparing phosphate soft glass liquid; and preparing the crystalline silicon double-sided multi-layer passivation film. The phosphate soft glass liquid is plated on the surface of the multi-layer composite film, so that the anti-cracking performance of the multi-layer composite film with silicon nitride as the main component is improved, in the high-temperature treatment process, the phosphate component can help to promote grain boundary movement, which is very beneficial to improving the quality and passivation effect of a silicon nitride / silicon interface, and the anti-cracking performance of the multi-layer composite film is improved. In addition, the phosphate soft glass is relatively low in elasticity modulus and can serve as a buffer layer between the silicon nitride film and the substrate, and the problem of deformation or cracks of the substrate possibly caused by high stress of silicon nitride can be relieved or balanced.

Description

Technical Field

[0001] The invention relates to the technical field of photovoltaic equipment, and in particular to a method for preparing a crystalline silicon double-sided multilayer passivation film. Background Art

[0002] Crystalline silicon double-sided multi-layer passivation film is an advanced surface treatment technology applied to crystalline silicon solar cells. This technology achieves fine passivation of the silicon wafer surface by depositing multiple layers of thin films of different materials on the front and back of the crystalline silicon wafer to reduce the recombination loss of charge carriers, thereby improving the energy conversion efficiency and long-term stability of the battery. These thin film layers usually contain intrinsic amorphous silicon (ia-Si:H), doped amorphous silicon (n / a-Si:H or p / a-Si:H), silicon nitride (SiNx), silicon oxide (SiOx), etc. Each layer has its specific function, and they work together to passivate surface defects, optimize interface properties and protect silicon wafers from environmental influences. Double-sided passivation is particularly suitable for crystalline silicon solar cells that generate electricity on both sides, which can effectively utilize the incident light from the back and increase power generation.

[0003] The existing crystalline silicon double-sided multilayer passivation film is mainly a film made of silicon nitride material. When the silicon nitride film is prepared by the plasma enhanced chemical vapor deposition (PECVD) method, high-speed ion bombardment will cause compressive stress inside the film. This is because the ions hit the surface of the film, causing the silicon atoms to be closely arranged and the volume to be reduced, thereby generating compressive stress, which may cause the crystalline silicon double-sided multilayer passivation film with silicon nitride as the main component to deform or even crack, thereby causing battery degradation. Therefore, the present invention provides a method for preparing a crystalline silicon double-sided multilayer passivation film to solve the problems existing in the above-mentioned prior art. Summary of the invention

[0004] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for preparing a double-sided multi-layer passivation film of crystalline silicon.

[0005] A method for preparing a crystalline silicon double-sided multilayer passivation film comprises the following steps:

[0006] S1: Pretreatment of base stainless steel sheet

[0007] A stainless steel sheet is prepared, the stainless steel sheet is mechanically ground, then polished to a mirror surface, ultrasonically cleaned in acetone and anhydrous ethanol in sequence, finally dried with a hair dryer, placed in a drying oven for standby use, and then coated on the stainless steel sheet by PECVD technology, wherein the gases used in the coating reaction are NH3 and SiH4, and a silicon nitride coating is obtained on the stainless steel sheet;

[0008] S2: Preparation of multilayer composite membranes

[0009] The surface of the silicon nitride coating is hydrophilized by using plasma surface treatment technology, the silicon nitride coating is placed in a plasma treatment machine, ethylene-tetrafluoroethylene copolymer ETFE is introduced, and after arcing, plasma grafting treatment is performed to obtain a double-layer composite film, the double-layer composite film is placed between two electrode plates in a plasma enhanced chemical vapor deposition system chamber, and then hexamethyldisiloxane monomer and reaction gas oxygen are introduced to perform plasma-assisted chemical vapor deposition of silicon dioxide to obtain a multi-layer composite film;

[0010] S3: Processing of multi-layer composite films

[0011] Butyl acetate and EtOH are mixed to prepare a mixed solvent, ethylenediaminetetraacetic acid, azobisisobutylcyanide and a cross-linking agent diaminohydroquinone are mixed and added into the mixed solvent to obtain a treatment solution, the multilayer composite membrane is heated under N2 protection, immersed in the treatment solution, and then reacted at a constant temperature to obtain a modified multilayer composite membrane;

[0012] S4: Preparation of phosphate soft glass liquid

[0013] Tetraethyl orthophosphate is added to an alcohol solution of phosphorus pentoxide, and then a hydrochloric acid solution is added to obtain a phosphate solution, the phosphate solution is fractionated to obtain a sol, and then the sol is added to an alcohol solution of tetraethyl orthophosphate and aluminum nitrate to obtain a phosphate soft glass liquid;

[0014] S5: Preparation of double-sided multilayer passivation film of crystalline silicon

[0015] The modified multi-layer composite film is immersed in phosphate soft glass liquid in a fume hood, and stays for 5-10 seconds to allow the substrate surface to be completely wetted, and then pulled upward and dried to obtain a crystalline silicon double-sided multi-layer passivation film.

[0016] Furthermore, step S1 of pre-treating the base stainless steel sheet comprises the following steps:

[0017] S1.1: Prepare a 1.5 cm × 1.5 cm stainless steel sheet, grind it mechanically with 400, 600, 800, and 1000 sandpaper in sequence, and then polish it to a mirror surface;

[0018] S1.2: Perform ultrasonic cleaning in acetone and anhydrous ethanol in sequence, and finally blow dry with a hair dryer and place in a drying oven for later use. Perform ultrasonic cleaning again with anhydrous ethanol before each use to ensure that the surface of the stainless steel sheet is clean;

[0019] S1.3: Then, the stainless steel sheet is coated by PECVD technology. The gases used in the coating reaction are NH3 and SiH4, and a silicon nitride coating is obtained on the stainless steel sheet.

[0020] Furthermore, step S2 of preparing a multilayer composite film comprises the following steps:

[0021] S2.1: The surface of the silicon nitride coating is hydrophilized by plasma surface treatment technology. The silicon nitride coating is placed in a plasma treatment machine, vacuumed to 0.3 mbar, and then ethylene-tetrafluoroethylene copolymer ETFE is introduced at 0.4 ml / min. At the same time, the power of the plasma treatment machine is adjusted to 50 W. After the arc is started, plasma grafting treatment is performed for 10-15 minutes to obtain a double-layer composite film.

[0022] S2.2: Place the double-layer composite film between the two electrode plates in the chamber of the plasma enhanced chemical vapor deposition system, evacuate to 102-104Pa, control the temperature of the double-layer composite film to 60-65°C, and the deposition time to 20-30min. Then, introduce hexamethyldisiloxane monomer and reaction gas oxygen at a rate of 300mL / min, adjust the plasma discharge power to 300w, generate plasma, and perform plasma-assisted chemical vapor deposition of silicon dioxide to obtain a multi-layer composite film.

[0023] Furthermore, step S3 processes the multilayer composite film, comprising the following steps:

[0024] S3.1: Butyl acetate and EtOH are mixed in a mass ratio of 1:4 to prepare a mixed solvent, ethylenediaminetetraacetic acid, azobisisobutylcyanide and a cross-linking agent diaminohydroquinone are mixed in a mass ratio of 1:1:2 and added into the mixed solvent in an amount of 20% of the total mass of the system to obtain a treatment solution;

[0025] S3.2: The multilayer composite membrane is heated to 74-76°C under N2 protection, immersed in the treatment solution, and then reacted at a constant temperature for 5-5.5 hours, and then the modified multilayer composite membrane is obtained.

[0026] Furthermore, step S4 prepares phosphate soft glass liquid, comprising the following steps:

[0027] S4.1: adding tetraethyl orthophosphate to an alcohol solution of phosphorus pentoxide, and then adding a hydrochloric acid solution, wherein the mass ratio of tetraethyl orthophosphate, the hydrochloric acid solution and the alcohol solution of phosphorus pentoxide is (1-2):(3-4):(3-5), to obtain a phosphate solution;

[0028] S4.2: fractionating the phosphate solution to obtain a sol, and then adding the sol to an alcohol solution of tetraethyl orthophosphate and aluminum nitrate, wherein the mass ratio of the sol, tetraethyl orthophosphate and the alcohol solution of aluminum nitrate is (1-2):(0.5-1):(5-6), to obtain a phosphate soft glass liquid;

[0029] Furthermore, step S5 prepares a double-sided multilayer passivation film of crystalline silicon, comprising the following steps:

[0030] S5.1: Immerse the modified multilayer composite film into the phosphate soft glass liquid in a fume hood for 5-10 seconds to allow the substrate surface to be completely wetted to avoid gaps;

[0031] S5.2: Then pull it upward at 60° at a speed of 6-8 cm / min and dry it at 60-80°C for 5-6 hours to obtain a double-sided multi-layer passivation film of crystalline silicon.

[0032] Furthermore, the thickness of the double-layer composite film is 100 nm.

[0033] Furthermore, during the entire grafting process, the vacuum pressure in the plasma treatment machine is maintained within 0.9 mbar during plasma grafting.

[0034] Furthermore, the thickness of the multilayer composite film is 200 nm.

[0035] Furthermore, the coating thickness of the crystalline silicon double-sided multilayer passivation film is 200-300nm.

[0036] Compared with the prior art, the present invention has at least the following beneficial effects:

[0037] 1. The present invention improves the crack resistance of the modified multilayer composite film with silicon nitride as the main component by coating the surface of the modified multilayer composite film with phosphate soft glass liquid. During the high-temperature treatment process, the phosphate component can help promote grain boundary movement, which is very beneficial to improving the quality and passivation effect of the silicon nitride / silicon interface. In addition, the elastic modulus of the phosphate soft glass is relatively low, and it can act as a buffer layer between the silicon nitride film and the substrate, which helps to alleviate the overall deformation and crack problems of the crystalline silicon double-sided multilayer passivation film caused by the high stress of silicon nitride.

[0038] 2. The present invention places the multilayer composite film in a treatment solution whose main components are ethylenediaminetetraacetic acid, azobisisobutylcyanide and a cross-linking agent diaminohydroquinone. The cross-linking agent diaminohydroquinone can react with the active points on the surface of the multilayer composite film to form covalent bonds, thereby achieving cross-linking modification between the film layers, thereby improving the adhesion between the multilayer composite film and the phosphate soft glass liquid, so that the prepared modified multilayer composite film has a slight cross-linking ability, so that when the phosphate soft glass film is subsequently coated, the phosphate soft glass liquid can be better wrapped on the surface of the modified multilayer composite film, thereby improving the bonding ability between the phosphate soft glass and the modified multilayer composite film, and reducing the possibility of deformation of the double-sided multilayer passivation film of crystalline silicon.

[0039] 3. The present invention deposits a silicon dioxide film on the surface of a silicon nitride film through vapor phase deposition. Since silicon dioxide itself has good insulating properties, it can enhance the dielectric strength and insulating properties after combining with the silicon nitride film. In addition, the vapor phase deposition technology can control the film growth at the atomic level, forming silicon dioxide nucleation points on the silicon nitride surface and gradually expanding outward to form a continuous film, so that a high-quality interface directly connected by covalent bonds is formed between silicon dioxide and silicon nitride, thereby improving the adhesion and electrical properties between the silicon dioxide film layer and the silicon nitride film layer, thereby improving the physical and electrical properties of the crystalline silicon double-sided multilayer passivation film. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable those skilled in the relevant art to make and use the present disclosure.

[0041] Figure 1 The present invention is a flow chart of a method for preparing a crystalline silicon double-sided multilayer passivation film used in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The following is a detailed description of a method for preparing a crystalline silicon double-sided multilayer passivation film provided by the present invention in conjunction with the accompanying drawings and specific embodiments. At the same time, it is explained here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art may also adopt other alternative methods to implement some known technologies; and the accompanying drawings are only for a more specific description of the embodiments, and are not intended to specifically limit the present invention.

[0043] Embodiment 1:

[0044] A method for preparing a crystalline silicon double-sided multilayer passivation film, such as Figure 1 As shown, the following steps are included:

[0045] S1: Pretreatment of base stainless steel sheet

[0046] S1.1: Prepare a 1.5 cm × 1.5 cm stainless steel sheet, grind it mechanically with 400, 600, 800, and 1000 sandpaper in sequence, and then polish it to a mirror surface;

[0047] S1.2: Perform ultrasonic cleaning in acetone and anhydrous ethanol in sequence, and finally blow dry with a hair dryer and place in a drying oven for later use. Perform ultrasonic cleaning again with anhydrous ethanol before each use to ensure that the surface of the stainless steel sheet is clean;

[0048] S1.3: Then, the stainless steel sheet is coated by PECVD technology. The gases used in the coating reaction are NH3 and SiH4, and a silicon nitride coating is obtained on the stainless steel sheet.

[0049] S2: Preparation of multilayer composite membranes

[0050] S2.1: The surface of the silicon nitride coating is hydrophilized by plasma surface treatment technology. The silicon nitride coating is placed in a plasma treatment machine, evacuated to 0.3 mbar, and then ethylene-tetrafluoroethylene copolymer ETFE is introduced at 0.4 ml / min. At the same time, the power of the plasma treatment machine is adjusted to 50 w. After the arc is started, the plasma grafting treatment is performed for 10 minutes. During the whole grafting treatment process, the vacuum pressure in the plasma treatment machine is maintained within 0.9 mbar during the plasma grafting, and a double-layer composite film is obtained. The thickness of the double-layer composite film is 100 nm.

[0051] S2.2: Place the double-layer composite film between the two electrode plates in the chamber of the plasma enhanced chemical vapor deposition system, evacuate to 102Pa, control the temperature of the double-layer composite film to 60°C, and the deposition time to 20min. Then, introduce hexamethyldisiloxane monomer and reaction gas oxygen at a rate of 300mL / min, adjust the plasma discharge power to 300w, generate plasma, and perform plasma-assisted chemical vapor deposition of silicon dioxide to obtain a multi-layer composite film. The thickness of the multi-layer composite film is 200nm.

[0052] S3: Processing of multi-layer composite films

[0053] S3.1: Butyl acetate and EtOH are mixed in a mass ratio of 1:4 to prepare a mixed solvent, ethylenediaminetetraacetic acid, azobisisobutylcyanide and a cross-linking agent diaminohydroquinone are mixed in a mass ratio of 1:1:2 and added into the mixed solvent in an amount of 20% of the total mass of the system to obtain a treatment solution;

[0054] S3.2: The multilayer composite membrane is heated to 74° C. under N2 protection, immersed in the treatment solution, and then reacted at a constant temperature for 5 hours, and then the modified multilayer composite membrane is obtained.

[0055] S4: Preparation of phosphate soft glass liquid

[0056] S4.1: adding tetraethyl orthophosphate to an alcohol solution of phosphorus pentoxide, and then adding a hydrochloric acid solution, wherein the mass ratio of tetraethyl orthophosphate, the hydrochloric acid solution and the alcohol solution of phosphorus pentoxide is 2:3:5, to obtain a phosphate solution;

[0057] S4.2: fractionating the phosphate solution to obtain a sol, and then adding the sol to an alcohol solution of tetraethyl orthophosphate and aluminum nitrate, wherein the mass ratio of the sol, tetraethyl orthophosphate and the alcohol solution of aluminum nitrate is 2:1:6, to obtain a phosphate soft glass liquid;

[0058] S5: Preparation of double-sided multilayer passivation film of crystalline silicon

[0059] S5.1: Immerse the modified multilayer composite membrane into the phosphate soft glass solution in a fume hood for 10 seconds to allow the substrate surface to be completely wetted to avoid gaps;

[0060] S5.2: Then pull it upward at 60° at a speed of 6 cm / min and dry it at 60°C for 5 hours to obtain a crystalline silicon double-sided multilayer passivation film. The coating thickness of the crystalline silicon double-sided multilayer passivation film is 300 nm.

[0061] Embodiment 2:

[0062] A method for preparing a crystalline silicon double-sided multilayer passivation film, such as Figure 1 As shown, the following steps are included:

[0063] S1: Pretreatment of base stainless steel sheet

[0064] S1.1: Prepare a 1.5 cm × 1.5 cm stainless steel sheet, grind it mechanically with 400, 600, 800, and 1000 sandpaper in sequence, and then polish it to a mirror surface;

[0065] S1.2: Perform ultrasonic cleaning in acetone and anhydrous ethanol in sequence, and finally blow dry with a hair dryer and place in a drying oven for later use. Perform ultrasonic cleaning again with anhydrous ethanol before each use to ensure that the surface of the stainless steel sheet is clean;

[0066] S1.3: Then, the stainless steel sheet is coated with a film by using PECVD technology. The gases used in the coating reaction are NH3 and SiH4, and a silicon nitride coating is obtained on the stainless steel sheet.

[0067] S2: Preparation of multilayer composite membranes

[0068] S2.1: The surface of the silicon nitride coating is hydrophilized by plasma surface treatment technology. The silicon nitride coating is placed in a plasma treatment machine, evacuated to 0.3 mbar, and then ethylene-tetrafluoroethylene copolymer ETFE is introduced at 0.4 ml / min. At the same time, the power of the plasma treatment machine is adjusted to 50 w. After the arc is started, the plasma grafting treatment is performed for 10 minutes. During the whole grafting treatment process, the vacuum pressure in the plasma treatment machine is maintained within 0.9 mbar during the plasma grafting, and a double-layer composite film is obtained. The thickness of the double-layer composite film is 100 nm.

[0069] S2.2: Place the double-layer composite film between the two electrode plates in the chamber of the plasma enhanced chemical vapor deposition system, evacuate to 102Pa, control the temperature of the double-layer composite film to 60°C, and the deposition time to 20min. Then, introduce hexamethyldisiloxane monomer and reaction gas oxygen at a rate of 300mL / min, adjust the plasma discharge power to 300w, generate plasma, and perform plasma-assisted chemical vapor deposition of silicon dioxide to obtain a multi-layer composite film. The thickness of the multi-layer composite film is 200nm.

[0070] S3: Processing of multi-layer composite films

[0071] S3.1: Butyl acetate and EtOH are mixed in a mass ratio of 1:4 to prepare a mixed solvent, ethylenediaminetetraacetic acid, azobisisobutylcyanide and a cross-linking agent diaminohydroquinone are mixed in a mass ratio of 1:1:2 and added into the mixed solvent in an amount of 20% of the total mass of the system to obtain a treatment solution;

[0072] S3.2: The multilayer composite membrane is heated to 74° C. under N2 protection, immersed in the treatment solution, and then reacted at a constant temperature for 5 hours, and then the modified multilayer composite membrane is obtained.

[0073] S4: Preparation of phosphate soft glass liquid

[0074] S4.1: adding tetraethyl orthophosphate to an alcohol solution of phosphorus pentoxide, and then adding a hydrochloric acid solution, wherein the mass ratio of tetraethyl orthophosphate, the hydrochloric acid solution and the alcohol solution of phosphorus pentoxide is 1:4:3, to obtain a phosphate solution;

[0075] S4.2: fractionating the phosphate solution to obtain a sol, and then adding the sol to an alcohol solution of tetraethyl orthophosphate and aluminum nitrate, wherein the mass ratio of the sol, tetraethyl orthophosphate and the alcohol solution of aluminum nitrate is 1:0.5:5, to obtain a phosphate soft glass liquid;

[0076] S5: Preparation of double-sided multilayer passivation film of crystalline silicon

[0077] S5.1: Immerse the modified multilayer composite membrane into the phosphate soft glass solution in a fume hood for 10 seconds to allow the substrate surface to be completely wetted to avoid gaps;

[0078] S5.2: Then pull it upward at 60° at a speed of 6 cm / min and dry it at 60°C for 5 hours to obtain a crystalline silicon double-sided multilayer passivation film. The coating thickness of the crystalline silicon double-sided multilayer passivation film is 300 nm.

[0079] Embodiment 3:

[0080] A method for preparing a crystalline silicon double-sided multilayer passivation film, such as Figure 1 As shown, the following steps are included:

[0081] S1: Pretreatment of base stainless steel sheet

[0082] S1.1: Prepare a 1.5 cm × 1.5 cm stainless steel sheet, grind it mechanically with 400, 600, 800, and 1000 sandpaper in sequence, and then polish it to a mirror surface;

[0083] S1.2: Perform ultrasonic cleaning in acetone and anhydrous ethanol in sequence, and finally blow dry with a hair dryer and place in a drying oven for later use. Perform ultrasonic cleaning again with anhydrous ethanol before each use to ensure that the surface of the stainless steel sheet is clean;

[0084] S1.3: Then, the stainless steel sheet is coated with a film by using PECVD technology. The gases used in the coating reaction are NH3 and SiH4, and a silicon nitride coating is obtained on the stainless steel sheet.

[0085] S2: Preparation of multilayer composite membranes

[0086] S2.1: The surface of the silicon nitride coating is hydrophilized by plasma surface treatment technology. The silicon nitride coating is placed in a plasma treatment machine, evacuated to 0.3 mbar, and then ethylene-tetrafluoroethylene copolymer ETFE is introduced at 0.4 ml / min. At the same time, the power of the plasma treatment machine is adjusted to 50 w. After the arc is started, the plasma grafting treatment is performed for 15 minutes. During the whole grafting treatment process, the vacuum pressure in the plasma treatment machine is maintained within 0.9 mbar during the plasma grafting, and a double-layer composite film is obtained. The thickness of the double-layer composite film is 100 nm.

[0087] S2.2: Place the double-layer composite film between the two electrode plates in the chamber of the plasma enhanced chemical vapor deposition system, evacuate to 104Pa, control the temperature of the double-layer composite film to 65°C, and the deposition time to 30min. Then, introduce hexamethyldisiloxane monomer and reaction gas oxygen at a rate of 300mL / min, adjust the plasma discharge power to 300w, generate plasma, and perform plasma-assisted chemical vapor deposition of silicon dioxide to obtain a multi-layer composite film. The thickness of the multi-layer composite film is 200nm.

[0088] S3: Processing of multi-layer composite films

[0089] S3.1: Butyl acetate and EtOH are mixed in a mass ratio of 1:4 to prepare a mixed solvent, ethylenediaminetetraacetic acid, azobisisobutylcyanide and a cross-linking agent diaminohydroquinone are mixed in a mass ratio of 1:1:2 and added into the mixed solvent in an amount of 20% of the total mass of the system to obtain a treatment solution;

[0090] S3.2: The multilayer composite membrane is heated to 76° C. under N2 protection, immersed in the treatment solution, and then reacted at a constant temperature for 5.5 hours, and then the modified multilayer composite membrane is obtained.

[0091] S4: Preparation of phosphate soft glass liquid

[0092] S4.1: adding tetraethyl orthophosphate to an alcohol solution of phosphorus pentoxide, and then adding a hydrochloric acid solution, wherein the mass ratio of tetraethyl orthophosphate, the hydrochloric acid solution and the alcohol solution of phosphorus pentoxide is 2:3:5, to obtain a phosphate solution;

[0093] S4.2: fractionating the phosphate solution to obtain a sol, and then adding the sol to an alcohol solution of tetraethyl orthophosphate and aluminum nitrate, wherein the mass ratio of the sol, tetraethyl orthophosphate and the alcohol solution of aluminum nitrate is 2:1:6, to obtain a phosphate soft glass liquid;

[0094] S5: Preparation of double-sided multilayer passivation film of crystalline silicon

[0095] S5.1: Immerse the modified multilayer composite membrane into the phosphate soft glass solution in a fume hood for 5 seconds to allow the substrate surface to be completely wetted to avoid gaps;

[0096] S5.2: Then pull it upward at 60° at a speed of 6 cm / min and dry it at 80°C for 6 hours to obtain a crystalline silicon double-sided multilayer passivation film. The coating thickness of the crystalline silicon double-sided multilayer passivation film is 300 nm.

[0097] Comparative Example 1:

[0098] Compared with Example 1, the difference of Comparative Example 1 is that in step S5, the modified multilayer composite film is not immersed in the phosphate soft glass liquid, but a layer of silicon carbide film is plated on the surface of the modified multilayer composite film, specifically: "S5: Preparation of crystalline silicon double-sided multilayer passivation film

[0099] A layer of SiC film is coated on the modified multilayer composite film by using an ion beam multifunctional sputtering coating device to obtain a crystalline silicon double-sided multilayer passivation film, and the thickness of the crystalline silicon double-sided multilayer passivation film is 300 nm. The crystalline silicon double-sided multilayer passivation film prepared in step S5 is recorded as comparative example 1.

[0100] Comparative Example 2:

[0101] Compared with Example 1, the difference of Comparative Example 2 is that step S3 is not performed, and the multilayer composite film is directly used in step S5 to prepare a crystalline silicon double-sided multilayer passivation film, specifically: "S5: Preparation of a crystalline silicon double-sided multilayer passivation film

[0102] S5.1: Immerse the multilayer composite film in phosphate soft glass solution in a fume hood for 10 seconds to allow the substrate surface to be completely wetted to avoid gaps;

[0103] S5.2: then pull it upward at 60° at a speed of 6 cm / min, and dry it at 60°C for 5 h to obtain a crystalline silicon double-sided multilayer passivation film, the coating thickness of the crystalline silicon double-sided multilayer passivation film is 300 nm. The crystalline silicon double-sided multilayer passivation film prepared in step S5 is recorded as Comparative Example 2.

[0104] Comparative Example 3:

[0105] Compared with Example 1, the difference of Comparative Example 3 is that step S2.2 is not performed in step S2, specifically: "S2: preparing a multilayer composite film

[0106] S2.1: The surface of the silicon nitride coating is hydrophilized by plasma surface treatment technology. The silicon nitride coating is placed in a plasma treatment machine, evacuated to 0.3 mbar, and then ethylene-tetrafluoroethylene copolymer ETFE is introduced at 0.4 ml / min. At the same time, the power of the plasma treatment machine is adjusted to 50 w. After the arc is started, the plasma grafting treatment is performed for 10 minutes. During the whole grafting treatment process, the vacuum pressure in the plasma treatment machine is maintained within 0.9 mbar during the plasma grafting, and a double-layer composite film is obtained. The thickness of the double-layer composite film is 100 nm.

[0107] S3: Processing of multi-layer composite films

[0108] S3.1: Butyl acetate and EtOH are mixed in a mass ratio of 1:4 to prepare a mixed solvent, ethylenediaminetetraacetic acid, azobisisobutylcyanide and a cross-linking agent diaminohydroquinone are mixed in a mass ratio of 1:1:2 and added into the mixed solvent in an amount of 20% of the total mass of the system to obtain a treatment solution;

[0109] S3.2: Raise the temperature of the double-layer composite film to 74°C under N2 protection, immerse it in the treatment solution, and then react at a constant temperature for 5 hours, thereby obtaining a modified multilayer composite film. The crystalline silicon double-sided multilayer passivation film prepared in step S5 is recorded as comparative example 3.

[0110] The crystalline silicon double-sided multilayer passivation films of Examples 1-3 and Comparative Examples 1-3 were placed in an accelerated UV aging device, respectively, and irradiated with a cumulative irradiation of 200 kWh / m 2 , and then refer to GB / T31034-2014 to test the elongation at break of the test specimens before and after aging.

[0111] Table 1: Elongation at break

[0112] Elongation at break (%) Example 1 157 Example 2 155 Example 3 154 Comparative Example 1 106 Comparative Example 2 119 Comparative Example 3 128

[0113] In the table, the elongations at break of Examples 1-3 are 157%, 155% and 154% respectively. The elongation at break can reflect the crack resistance of the tested sample. The higher the elongation at break, the less likely the tested sample is to break and the better the crack resistance.

[0114] The elongation at break of comparative example 1 is only 106%. It can be seen that when the crystalline silicon double-sided multilayer passivation film with silicon nitride film as the main material is prepared by the plasma enhanced chemical vapor deposition method, high-speed ion bombardment will cause compressive stress inside the film, resulting in large internal stress of the silicon nitride film, which is prone to deformation and cracking when exposed to the external environment for a long time, and finally leads to fracture.

[0115] The elongation at break of Comparative Example 2 is 119%, which shows that the presence of phosphate soft glass improves the crack resistance of the crystalline silicon double-sided multilayer passivation film. However, due to the lack of treatment, the adhesion between the phosphate soft glass and the multilayer composite film is insufficient, and the performance improvement is limited.

[0116] The elongation at break of comparative example 3 is 128%, which shows that the vapor-deposited silicon dioxide film on the surface of the silicon nitride film also has the effect of improving the physical properties of the crystalline silicon double-sided multilayer passivation film, and the phosphate soft glass has a greater improvement on the crack resistance of the crystalline silicon double-sided multilayer passivation film.

[0117] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing a crystalline silicon double-sided multilayer passivation film, characterized in that: The steps include: S1: Pretreatment of base stainless steel sheet Prepare stainless steel sheets, grind them mechanically, polish them to a mirror surface, clean them ultrasonically in acetone and anhydrous ethanol, dry them with a hair dryer, place them in a drying oven for later use, and then coat them on the stainless steel sheets using PECVD technology. The gases used in the coating reaction are NH3 and SiH4, to obtain silicon nitride coating on stainless steel sheet; S2: Preparation of multilayer composite membranes The surface of the silicon nitride coating is hydrophilized by using plasma surface treatment technology, the silicon nitride coating is placed in a plasma treatment machine, ethylene-tetrafluoroethylene copolymer ETFE is introduced, and after arcing, plasma grafting treatment is performed to obtain a double-layer composite film, the double-layer composite film is placed between two electrode plates in a plasma enhanced chemical vapor deposition system chamber, and then hexamethyldisiloxane monomer and reaction gas oxygen are introduced to perform plasma-assisted chemical vapor deposition of silicon dioxide to obtain a multi-layer composite film; S3: Processing of multi-layer composite films Butyl acetate and EtOH are mixed to prepare a mixed solvent, ethylenediaminetetraacetic acid, azobisisobutylcyanide and a cross-linking agent diaminohydroquinone are mixed and added into the mixed solvent to obtain a treatment solution, the multilayer composite membrane is heated under N2 protection, immersed in the treatment solution, and then reacted at a constant temperature to obtain a modified multilayer composite membrane; S4: Preparation of phosphate soft glass liquid Tetraethyl orthophosphate is added to an alcohol solution of phosphorus pentoxide, and then a hydrochloric acid solution is added to obtain a phosphate solution, the phosphate solution is fractionated to obtain a sol, and then the sol is added to an alcohol solution of tetraethyl orthophosphate and aluminum nitrate to obtain a phosphate soft glass liquid; S5: Preparation of double-sided multilayer passivation film of crystalline silicon The modified multi-layer composite film is immersed in phosphate soft glass liquid in a fume hood, and stays for 5-10 seconds to allow the substrate surface to be completely wetted, and then pulled upward and dried to obtain a crystalline silicon double-sided multi-layer passivation film.

2. The method for preparing a crystalline silicon double-sided multilayer passivation film according to claim 1, characterized in that: Step S1: pretreatment of the base stainless steel sheet, including the following steps: S1.1: Prepare a 1.5 cm × 1.5 cm stainless steel sheet, grind it mechanically with 400, 600, 800, and 1000 sandpaper in sequence, and then polish it to a mirror surface; S1.2: Perform ultrasonic cleaning in acetone and anhydrous ethanol in sequence, and finally blow dry with a hair dryer and place in a drying oven for later use. Perform ultrasonic cleaning again with anhydrous ethanol before each use to ensure that the surface of the stainless steel sheet is clean; S1.3: Then, the stainless steel sheet is coated by PECVD technology. The gases used in the coating reaction are NH3 and SiH4, and a silicon nitride coating is obtained on the stainless steel sheet.

3. The method for preparing a crystalline silicon double-sided multilayer passivation film according to claim 2, characterized in that: Step S2 prepares a multilayer composite film, comprising the following steps: S2.1: The surface of the silicon nitride coating is hydrophilized by plasma surface treatment technology. The silicon nitride coating is placed in a plasma treatment machine, vacuumed to 0.3 mbar, and then ethylene-tetrafluoroethylene copolymer ETFE is introduced at 0.4 ml / min. At the same time, the power of the plasma treatment machine is adjusted to 50 W. After the arc is started, plasma grafting treatment is performed for 10-15 minutes to obtain a double-layer composite film. S2.2: Place the double-layer composite film between the two electrode plates in the chamber of the plasma enhanced chemical vapor deposition system, evacuate to 102-104Pa, control the temperature of the double-layer composite film to 60-65°C, and the deposition time to 20-30min. Then, introduce hexamethyldisiloxane monomer and reaction gas oxygen at a rate of 300mL / min, adjust the plasma discharge power to 300w, generate plasma, and perform plasma-assisted chemical vapor deposition of silicon dioxide to obtain a multi-layer composite film.

4. The method for preparing a crystalline silicon double-sided multilayer passivation film according to claim 3, characterized in that: Step S3 processes the multilayer composite film, comprising the following steps: S3.1: Butyl acetate and EtOH are mixed in a mass ratio of 1:4 to prepare a mixed solvent, ethylenediaminetetraacetic acid, azobisisobutylcyanide and a cross-linking agent diaminohydroquinone are mixed in a mass ratio of 1:1:2 and added into the mixed solvent in an amount of 20% of the total mass of the system to obtain a treatment solution; S3.2: The multilayer composite membrane is heated to 74-76°C under N2 protection, immersed in the treatment solution, and then reacted at a constant temperature for 5-5.5 hours, and then the modified multilayer composite membrane is obtained.

5. The method for preparing a crystalline silicon double-sided multilayer passivation film according to claim 4, characterized in that: Step S4 is to prepare phosphate soft glass liquid, comprising the following steps: S4.1: adding tetraethyl orthophosphate to an alcohol solution of phosphorus pentoxide, and then adding a hydrochloric acid solution, wherein the mass ratio of tetraethyl orthophosphate, the hydrochloric acid solution and the alcohol solution of phosphorus pentoxide is (1-2):(3-4):(3-5), to obtain a phosphate solution; S4.2: Fractionate the phosphate solution to obtain a sol, and then add the sol to an alcohol solution of tetraethyl orthophosphate and aluminum nitrate. The mass ratio of the sol, tetraethyl orthophosphate and the alcohol solution of aluminum nitrate is (1-2):(0.5-1):(5-6) to obtain a phosphate soft glass liquid.

6. The method for preparing a crystalline silicon double-sided multilayer passivation film according to claim 5, characterized in that: Step S5 is to prepare a double-sided multilayer passivation film of crystalline silicon, comprising the following steps: S5.1: Immerse the modified multilayer composite film into the phosphate soft glass liquid in a fume hood for 5-10 seconds to allow the substrate surface to be completely wetted to avoid gaps; S5.2: Then pull it upward at 60° at a speed of 6-8 cm / min and dry it at 60-80°C for 5-6 hours to obtain a double-sided multi-layer passivation film of crystalline silicon.

7. The method for preparing a crystalline silicon double-sided multilayer passivation film according to claim 6, characterized in that: The thickness of the double-layer composite film is 100 nm.

8. The method for preparing a crystalline silicon double-sided multilayer passivation film according to claim 7, characterized in that: During the whole grafting process, the vacuum pressure in the plasma treatment machine is maintained within 0.9 mbar when the plasma treatment machine is performing plasma grafting.

9. The method for preparing a crystalline silicon double-sided multilayer passivation film according to claim 8, characterized in that: The thickness of the multilayer composite film is 200 nm.

10. The method for preparing a crystalline silicon double-sided multilayer passivation film according to claim 9, characterized in that: The coating thickness of the crystalline silicon double-sided multilayer passivation film is 200-300nm.

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