Low-cost contact-passivated all-back contact solar cells and methods for fabricating same

Abstract

The present invention discloses a low-cost contact passivation all back contact solar cell and its manufacturing method, which includes the steps of: using a P-type single crystal silicon wafer (2) as a silicon substrate, performing an alkaline polishing process S1, performing RCA cleaning and HF cleaning S2, growing a tunnel silicon oxide thin film layer, an in-situ doped amorphous silicon thin film layer, and a texturing mask layer on the back surface of the silicon wafer (2) S3, performing annealing activation on the amorphous silicon thin film layer to convert it into a polycrystalline silicon thin film layer (3) S4, laser etching the texturing mask layer S5, performing double-sided texturing on the silicon wafer (2) S6, performing HF cleaning and texturing S7, and then performing a 3D laser etching process on the texturing mask layer S8. The method includes steps S7 of removing the charring mask layer, S8 of depositing an aluminum oxide thin film on the front and back surfaces of the silicon wafer (2), S9 of depositing a silicon nitride passivation film or a silicon nitride / silicon nitride oxide laminated passivation film on the front and back surfaces of the silicon wafer (2), S10 of laser ablation of a part of the aluminum oxide thin film and a part of the silicon nitride passivation film or the silicon nitride / silicon nitride oxide laminated passivation film on the back surface of the silicon wafer (2), and S11 of screen printing on the back surface of the silicon wafer (2) and sintering, in which silver paste is used for the contact passivation region and aluminum paste is used for the back surface region.

Description

[Technical Field]

[0001] The present invention relates to the technical field of crystalline silicon solar cells, and in particular to low-cost contact-passivated all-back contact solar cells and methods for their manufacture. [Background technology]

[0002] All-back contact cells are the most efficient and potentially promising cell structure among current crystalline silicon solar cells. Both the positive and negative electrodes are located on the back side of the cell. Compared to conventional cells, this completely eliminates the shading loss of the front gridlines and provides more space for rear-surface structural design. Contact passivation technology (TopCon) is considered the most promising next-generation passivation technology following PERC cell technology. It utilizes the passivation effect of the tunnel oxide layer and the good metal area of ​​the polysilicon thin film layer to significantly reduce recombination under the cell's metal gridlines. In recent years, the combination of all-back contact and contact passivation technology has become an industry research hotspot. Photovoltaic companies and scientific research institutes, such as SunPower in the US, Fraunhofer ISE Research Institute in Germany, and ISFH Research Institute in Germany, have all made relatively good progress in mass production and laboratory testing, with cell conversion efficiencies exceeding 25% for large areas and 26% for small areas, demonstrating excellent prospects for industrial application.

[0003] However, the manufacturing methods for these all-back contact cells described above are complex and expensive, and upgrading existing PERC production lines incurs significant costs. "Increasing efficiency and reducing costs" is a perennial theme in the photovoltaic industry. As PERC cell efficiency gradually approaches its theoretical limit, it is necessary to develop new cell technologies that can be upgraded and used on existing PERC production lines to change generations. This will extend the service life of existing PERC equipment and reduce the industry-wide cell manufacturing cost per watt. Furthermore, with the continuous improvement of p-type silicon wafer materials, their minority carrier lifetimes are becoming longer, meeting the technical requirements of all-back contact cell structures. Summary of the Invention

[0004] The objective of the present invention is to provide a process-compatible, low-cost manufacturing method for contact-passivated all-back contact solar cells, which can be used to upgrade new cell technologies and change generations based on conventional PERC manufacturing lines, extend the service life of conventional PERC equipment, and reduce the manufacturing cost per watt of cells across the industry.

[0005] The present invention is realized by the following technical solution: a method for manufacturing a low-cost contact-passivated all-back contact solar cell, The method comprises the following steps in order: S1: using a P-type single crystal silicon wafer as a silicon substrate and performing alkaline polishing on the silicon substrate; After alkaline polishing, S2 performs high-cleanliness RCA cleaning and HF cleaning. growing a tunnel silicon oxide thin film layer, an in-situ doped amorphous silicon thin film layer, and a texturing mask layer on the backside of the silicon wafer (S3); S4 performing anneal activation on the amorphous silicon thin film layer, thereby converting the amorphous silicon thin film layer into a polycrystalline silicon thin film layer; S5 laser etching the texturing mask layer on the backside of the silicon wafer; S6, double-sided texturing the silicon wafer; S7: performing HF cleaning after texturing and removing the texturing mask layer; S8 depositing an aluminum oxide thin film simultaneously on the front and back surfaces of the silicon wafer; S9 depositing a silicon nitride passivation film or a silicon nitride / silicon oxynitride laminated passivation film on the front and back surfaces of the silicon wafer; S10: laser ablating a portion of the aluminum oxide thin film and a portion of the silicon nitride passivation film or the silicon nitride / silicon nitride oxide stacked passivation film on the rear surface of the silicon wafer; S11: screen printing is performed on the backside of the silicon wafer and sintered; wherein the contact passivation area uses silver paste and the backside area uses aluminum paste.

[0006] Specifically, the manufacturing method for low-cost P-type silicon wafer contact passivation type all back contact crystalline silicon solar cells designed by the solution of the present invention involves using a P-type single crystalline silicon wafer as the silicon substrate, first polishing it, then growing a tunnel silicon oxide thin film layer, a doped amorphous silicon thin film layer, and a texturing mask layer on the back surface of the cell, the three film layers being deposited in the same equipment, annealing and activating the amorphous silicon layer, followed by laser ablation of the mask layer in the P-type region on the back surface of the cell, further texturing, depositing an aluminum oxide thin film on both sides, depositing an anti-reflective passivation film on the front and back surfaces of the cell respectively, and laser ablation of part of the aluminum oxide / anti-reflective passivation film in the back surface field region on the back surface to form a local aluminum back surface field, and finally printing and sintering the electrodes.

[0007] The low-cost contact passivation all-back contact solar cell manufacturing method designed and proposed by the present invention makes full use of the single-sided coating characteristics of PECVD and the ability to flexibly grow multiple types of thin films within a single cavity, and completes the contact passivation structure film layer and the mask film layer of the all-back contact cell in a single process step, effectively reducing the process steps, reducing the consumption of silver paste, and improving cell efficiency.

[0008] Furthermore, there is provided a method for manufacturing a low-cost contact-passivated all-back electrode solar cell, in which step S1 comprises using a P-type single crystal silicon wafer as a silicon substrate, the silicon wafer having a resistivity of 0.5-5 Ohmcm and a thickness of 120-200 μm, and then performing an alkaline polishing treatment on the silicon substrate at 75-85°C using a 15-30 wt% KOH solution.

[0009] Further, there is provided a method for manufacturing a low-cost contact-passivated all-back contact solar cell, in which step S3 uses a single-sided deposition PECVD tube or plate-type equipment to perform three-in-one multilayer thin film deposition on the back surface of the silicon wafer to grow a tunnel silicon oxide thin film layer, an in-situ doped amorphous silicon thin film layer, and a texturing mask layer, wherein the tunnel silicon oxide thin film layer has a thickness of less than 2 nm, the amorphous silicon thin film layer is a thin film formed by in-situ doping and has a thickness of 50-200 nm, and the texturing mask layer has a thickness of 50-100 nm, and may be made of SiONx (silicon nitride oxide), SiOx (silicon oxide), or SiNx (silicon nitride).

[0010] Further, a low-cost contact passivation all back contact solar cell manufacturing method is provided, in which step S4 performs annealing activation on the amorphous silicon thin film layer, thereby converting the amorphous silicon thin film layer into a polycrystalline silicon thin film layer, and controlling the sheet resistance to 50-100 ohm / sq, wherein the annealing activation can be performed using a tube oxidation furnace, the process temperature is 700-900°C, the annealing activation time is 1-2 hours, and the doping concentration after activation is 1e18-5e20 cm -3 A manufacturing method that is between.

[0011] Furthermore, there is provided a method for manufacturing a low-cost contact-passivated all-back contact solar cell, in which step S6 involves using potassium hydroxide or tetramethylammonium hydroxide solution to perform double-sided texturing on the silicon wafer to form a textured structure for light trapping.

[0012] Furthermore, there is provided a method for manufacturing a low-cost contact-passivated all-back contact solar cell, in which step S7 comprises performing a 5-20 wt% HF clean after texturing to remove the deposited texturing mask layer.

[0013] Furthermore, there is provided a method for manufacturing a low-cost contact-passivated all-back contact solar cell, in which step S8 uses a double-sided deposition ALD tube-type or plate-type equipment to deposit the aluminum oxide thin film simultaneously on the front and back surfaces of the silicon wafer, and the thickness of the aluminum oxide thin film is 2 to 20 nm.

[0014] Furthermore, there is provided a low-cost method for manufacturing a contact-passivated all-back electrode solar cell, in which step S9 uses a tube-type or plate-type PECVD to deposit a silicon nitride passivation film or a silicon nitride / silicon oxynitride laminated passivation film on the front and back surfaces of the silicon wafer, respectively, and the thickness of the passivation film is 50-100 nm and the refractive index is 1.9-2.4.

[0015] Furthermore, there is provided a method for manufacturing a low-cost contact-passivated all back contact solar cell, wherein the sintering temperature in step S11 is 700 to 900°C.

[0016] A low-cost contact-passivated all-back contact solar cell, manufactured by the above manufacturing method, characterized in that the manufactured all-back contact solar cell includes: a P-type monocrystalline silicon wafer; a front surface passivation film layer located on a front surface of the P-type monocrystalline silicon wafer; a polycrystalline silicon thin film layer located on a back surface of the P-type monocrystalline silicon wafer; an Al-BSF layer; a back surface passivation film layer; a first electrode located under the polycrystalline silicon thin film layer; and a second electrode located under the Al-BSF layer.

[0017] Specifically, the method for fabricating a low-cost contact-passivated all-back contact solar cell according to the present invention includes the following specific steps:

[0018] In S1, a P-type single crystal silicon wafer is used as a silicon substrate, and the silicon substrate is subjected to alkaline polishing treatment. The chemical used for alkaline polishing is a 15 to 30 wt % KOH solution, and the process temperature is 75 to 85°C.

[0019] In S2, after alkaline polishing, high-cleanliness RCA cleaning and HF cleaning are performed.

[0020] S3 grows a three-in-one multilayer thin film on the backside of the silicon wafer, consisting of a tunnel silicon oxide thin film layer, an in-situ doped amorphous silicon thin film layer (TopCon layer), and a texturing mask layer. The TopCon layer can be deposited using a phosphane + silane + hydrogen gas in-situ doping process. The texturing mask layer can be flexibly selected from thin films such as silicon oxide, silicon oxynitride, or silicon nitride depending on the subsequent process. The function of the texturing mask layer is to resist corrosion by potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH) solution during the subsequent double-sided texturing process.

[0021] S4 then performs annealing activation on the amorphous silicon thin film to activate the in-situ doped phosphorus atoms and simultaneously convert the amorphous silicon thin film layer deposited by PECVD into a polycrystalline silicon thin film layer. At high temperatures, hydrogen atoms in the thin film layer diffuse to the SiO2 / Si interface to saturate the surface dangling bonds and increase passivation. This step can be performed using a tubular oxidation furnace at a process temperature of 700-900°C.

[0022] S5 laser etches the above texturing mask layer on the backside of the silicon wafer, using a laser to groove a certain area (BSF area) on the backside of the cell silicon wafer, and ablate and remove a portion of the texturing mask layer deposited in step S3.

[0023] In step S6, the silicon wafer is then subjected to double-sided alkaline texturing, where the polycrystalline silicon thin film layer deposited in step S3 is protected by a texturing mask layer to form a textured structure of front-side pyramids and back-side BSF pyramids. Before texturing, the silicon wafer is pre-cleaned with HF to remove the oxide layer formed on the surface of the silicon wafer and reduce its impact on the uniformity of the texturing.

[0024] In step S7, after texturing, HF cleaning is performed to completely remove the texturing mask layer remaining on the rear surface of the silicon wafer.

[0025] S8 uses a double-sided ALD tube or plate system to simultaneously deposit a thin aluminum oxide film on both the front and back surfaces of the silicon wafer. The negatively charged aluminum oxide (AlOx) provides good field passivation for p-type silicon, but the TopCon layer is not affected.

[0026] In step S9, a silicon nitride passivation film or a silicon nitride / silicon oxynitride laminated passivation film is deposited on the front and back surfaces of the silicon wafer.

[0027] In step S10, a portion of the aluminum oxide thin film and a portion of the silicon nitride passivation film or silicon nitride / silicon nitride oxide stacked passivation film on the backside of the silicon wafer are laser ablated, i.e., a groove cutting process is performed using a laser on a certain area (BSF area) on the backside of the cell, ablation of a portion of the AlOx / SiNx / SiONx film layer deposited in step S9 is performed, and an Al-BSF layer is formed in the sintering process in preparation for direct contact between the Al slurry electrode and the Si surface.

[0028] In step S11, the backside of the silicon wafer is screen-printed and sintered. Silver paste is used in the contact passivation area and aluminum paste is used in the backside area. Specifically, Ag electrodes and Al electrodes are screen-printed in the TopCon area and BSF area, respectively. The final sintering process is performed using a general sintering furnace in the PERC production line, with the peak temperature controlled at 700-900°C.

[0029] Beneficial effects of the present invention: (1) The manufacturing method of the low-cost contact-passivated all-back contact solar cell designed by the present invention can produce solar cells with better cost performance and higher efficiency with relatively little upgrade modification to the existing PREC cell manufacturing line. The P-type all-back contact solar cell of the present invention has advantages such as good process compatibility, high photoelectric conversion efficiency, and low manufacturing cost, and is of great significance for promoting the mass production of low-cost, high-performance solar cells.

[0030] (2) The present invention provides a low-cost method for manufacturing contact-passivated all-back contact solar cells, which uses PECVD to deposit a tunnel oxide layer, a polysilicon thin film layer, and a texturing mask layer on one side, and utilizes conventional equipment in PERC manufacturing lines, such as laser SE, laser groove and diffusion oxidation, and print sintering, to maximize the retention of conventional PERC equipment while simultaneously reducing cost per watt and improving efficiency.

[0031] (3) The low-cost contact passivation all-back contact solar cell fabrication method provided by the present invention fully utilizes the characteristics of PECVD, namely, single-sided coating and the ability to flexibly grow various thin films within a single cavity, to complete the contact passivation structure film layer and the mask film layer of the all-back contact cell in a single process step, effectively reducing the process steps, reducing the consumption of silver paste, and improving cell efficiency.

[0032] (4) The present invention is superior in that it is a one-step process for depositing multilayer thin films on the backside of silicon wafers. In conventional technologies, the deposition of tunnel silicon oxide thin film, intrinsic polycrystalline silicon thin film, and silicon nitride thin film must be completed using different equipment. This requires more automated operations such as loading and unloading during the battery manufacturing process, which significantly impacts production yield. Furthermore, the conventional process is completed in stages, requiring more thermal processes and temperature rise / fall processes, which also impacts battery efficiency. However, the present invention uses a three-in-one multilayer thin film deposition process and a one-step method to overcome these problems of the conventional process. [Brief explanation of the drawings]

[0033] In order to more clearly explain the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings used in the description of the embodiments. Of course, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can further derive other drawings based on these drawings without any creative work.

[0034] [Figure 1] 1 is a structural schematic diagram of a low-cost contact-passivated all-back contact solar cell manufactured according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0035] The following provides a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the drawings in the embodiments of the present invention. Of course, the described embodiments are only a part of the embodiments of the present invention, and are not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is not intended to impose any limitations on the present invention and its application or use. Any other embodiments that can be obtained by those skilled in the art based on the embodiments of the present invention without any novel work are also within the scope of the claims of the present invention.

[0036] Example 1 A method for fabricating a low-cost contact-passivated all-back contact solar cell includes the following specific steps:

[0037] In S1, a P-type single crystal silicon wafer is used as the silicon substrate, and the resistivity of the silicon wafer is 0.5 to 5 Ohmcm and the thickness is 120 to 200 μm. Next, the silicon substrate is subjected to an alkaline polishing treatment at 75 to 85°C using a 15 to 30 wt% potassium hydroxide (KOH) solution.

[0038] In S2, after alkaline polishing treatment, high-cleanliness RCA cleaning and HF cleaning are performed.

[0039] S3 uses tube-type (or plate-type) PECVD to perform single-sided deposition on the backside of a P-type monocrystalline silicon wafer, depositing a three-in-one multilayer film on the backside of the wafer. The multilayer film consists of a tunnel silicon oxide film, an in-situ doped amorphous silicon film (TopCon layer), and a texturing mask layer. The tunnel silicon oxide film is less than 2 nm thick, the amorphous silicon film is an in-situ doped film with a thickness of 50-200 nm, and the texturing mask layer is 50-100 nm thick and made of SiNx. The TopCon layer can be deposited using a phosphane-silane-hydrogen gas in-situ doping deposition process. The function of the texturing mask layer is to resist corrosion by potassium hydroxide or tetramethylammonium hydroxide solution during the subsequent double-sided texturing process.

[0040] In step S4, the amorphous silicon thin film is annealed and activated using a tube oxidation furnace. The purpose is to activate the in-situ doped phosphorus atoms and simultaneously convert the amorphous silicon thin film layer deposited by PECVD into a polycrystalline silicon thin film layer, controlling the sheet resistance to 50-100 ohm / sq. In addition, during the high-temperature process, hydrogen atoms in the thin film layer diffuse to the SiO2 / Si interface to saturate the surface dangling bonds and increase the passivation effect. The annealing activation process temperature in this step is 700-900°C, the annealing activation time is 1-2 hours, and the doping concentration after activation is 1e18-5e20. cm -3 It is between.

[0041] S5 laser etches the above texturing mask layer on the backside of the silicon wafer, using a laser to groove a certain area (BSF area) on the backside of the cell silicon wafer and ablate a portion of the texturing mask layer deposited in step S3.

[0042] In step S6, a potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH) solution is subsequently used to perform double-sided alkaline texturing on the P-type single-crystalline silicon wafer (the polycrystalline silicon thin film layer deposited in step S3 is protected by a texturing mask layer), forming a textured structure of front-side pyramids and back-side BSF pyramids. Prior to texturing, the silicon wafer is pre-cleaned with HF to remove the oxide layer formed on the surface of the silicon wafer and reduce its impact on the uniformity of the texturing.

[0043] In step S7, after texturing, 5 to 20 wt % HF cleaning is performed to completely remove the texturing mask layer remaining on the rear surface of the silicon wafer.

[0044] S8 uses a double-sided ALD tube or plate-type system to simultaneously deposit a 2-20 nm thick aluminum oxide thin film on both the front and back surfaces of the silicon wafer. The negatively charged aluminum oxide (AlOx) provides good field passivation for P-type silicon, but the TopCon layer is not affected.

[0045] S9 uses tube-type or plate-type PECVD to deposit a silicon nitride passivation film or a silicon nitride / silicon nitride oxide laminated passivation film on the front and back surfaces of a silicon wafer, respectively, with a thickness of 50-100 nm and a refractive index of 1.9-2.4.

[0046] In step S10, a portion of the aluminum oxide thin film and a portion of the silicon nitride passivation film or silicon nitride / silicon nitride oxide stacked passivation film on the backside of the silicon wafer are laser ablated, i.e., a groove cutting process is performed using a laser on a certain area (BSF area) on the backside of the cell, ablation of a portion of the AlOx / SiNx / SiONx film layer deposited in step S9 is performed, and an Al-BSF layer is formed in the sintering process in preparation for direct contact between the Al slurry electrode and the Si surface.

[0047] In step S11, Ag electrodes and Al electrodes are screen-printed in the TopCon region and BSF region, respectively, and the final sintering process is carried out using a general sintering furnace in the PERC production line, with the sintering temperature controlled at 700-900°C, completing the production of the P-type all back contact solar cell.

[0048] As shown in FIG. 1 , the low-cost P-type silicon wafer contact passivation type all back surface contact silicon solar cell manufactured according to the present invention includes a P-type single crystal silicon wafer 2, a front surface passivation film layer 1 located on the front surface of the P-type single crystal silicon wafer 2, a polycrystalline silicon thin film layer 3 located on the back surface of the P-type single crystal silicon wafer 2, an Al-BSF layer 4, a back surface passivation film layer 5, a first electrode 6 located under the polycrystalline silicon thin film layer 3, and a second electrode 7 located under the Al-BSF layer 4.

[0049] The solution designed in this invention can be used on existing PREC cell production lines with relatively little upgrade modification, and can produce solar cells with better cost performance and higher efficiency. The resulting P-type all-back contact solar cells have the advantages of good process compatibility, high photoelectric conversion efficiency, and low manufacturing costs, which is of great significance for promoting the mass production of low-cost, high-performance solar cells.

[0050] The above are preferred embodiments of the present invention, which are only for illustrating the present invention, not for limiting the present invention. Any obvious changes or modifications introduced by the technical solutions of the present invention still fall within the protection scope of the present invention. [Explanation of symbols]

[0051] 1. Surface passivation film layer 2 P-type monocrystalline silicon wafers 3 Polycrystalline silicon thin film layer 4 Al-BSF layer 5 Backside passivation layer 6 1st electrode 7 Second electrode

Claims

1. A method for manufacturing a contact-passivated all-back contact solar cell, the method comprising the following steps in order: S1: a P-type single crystal silicon wafer is used as a silicon substrate, and the silicon substrate is subjected to alkaline polishing; S2: After the alkaline polishing treatment, RCA cleaning and HF cleaning are performed; S3 growing a tunnel silicon oxide thin film layer, an in-situ doped amorphous silicon thin film layer, and a texturing mask layer on the backside of the silicon wafer; S4: performing anneal activation on the amorphous silicon thin film layer, thereby converting the amorphous silicon thin film layer into a polycrystalline silicon thin film layer; S5 laser etching the texturing mask layer on the backside of the silicon wafer; S6 double-sided texturing of the silicon wafer; S7: performing HF cleaning after texturing and removing the texturing mask layer; S8 depositing an aluminum oxide thin film on both the front and back surfaces of the silicon wafer at the same time; S9 depositing a silicon nitride passivation film or a silicon nitride / silicon oxynitride laminated passivation film on the front and back surfaces of the silicon wafer; S10 laser ablating a portion of the aluminum oxide thin film and a portion of the silicon nitride passivation film or the silicon nitride / silicon nitride oxide stacked passivation film on the rear surface of the silicon wafer; S11: screen-printing an Ag electrode and an Al electrode in the TopCon region and the BSF region of the backside of the silicon wafer, respectively, and sintering the electrodes; In step S11, the TopCon region has a region having a passivation film layer as a contact passivation region, and silver paste is used for the contact passivation region, and the BSF region has a back surface region which is a fixed region, and aluminum paste is used for the back surface region.

2. 2. The method for manufacturing a contact passivation all back electrode solar cell according to claim 1, characterized in that in step S1, the silicon substrate is a P-type single crystal silicon wafer, and the resistivity of the silicon wafer is 0.5-5 Ohmcm and the thickness is 120-200 μm; and then, an alkali polishing treatment is performed on the silicon substrate using a 15-30 wt % KOH solution at 75-85°C.

3. Step S3 uses a single-sided deposition PECVD tube or plate equipment to perform a three-in-one multilayer thin film deposition on the backside of the silicon wafer, growing the tunnel silicon oxide thin film layer, the in-situ doped amorphous silicon thin film layer, and the texturing mask layer; and 2. The method for manufacturing a contact-passivated all-back electrode solar cell according to claim 1, wherein the tunnel silicon oxide thin film layer has a thickness of less than 2 nm, the amorphous silicon thin film layer is a thin film formed by in-situ doping and has a thickness of 50-200 nm, and the texturing mask layer has a thickness of 50-100 nm and is made of SiONx, SiOx or SiNx.

4. 2. The method for manufacturing a contact-passivated all back contact solar cell of claim 1, wherein step S4 performs annealing activation on the amorphous silicon thin film layer, thereby converting the amorphous silicon thin film layer into the polycrystalline silicon thin film layer and controlling the sheet resistance to 50-100 ohm / sq, wherein the annealing activation in step S4 is performed using a tube oxidation furnace, the process temperature is 700-900°C, the annealing activation time is 1-2 hours, and the doping concentration after activation is between 1e18-5e20 cm-3.

5. 2. The method for manufacturing a contact-passivated all-back electrode solar cell according to claim 1, wherein step S6 uses potassium hydroxide or tetramethylammonium hydroxide solution to perform double-sided texturing on the silicon wafer to form a textured structure for light trapping.

6. 2. The method for fabricating a contact-passivated all-back contact solar cell according to claim 1, wherein step S7 comprises performing a 5-20 wt% HF clean after texturing to remove the deposited texturing mask layer.

7. 2. The method for manufacturing a contact-passivated all-back electrode solar cell according to claim 1, wherein step S8 uses a double-sided deposition ALD tube or plate-type equipment to simultaneously deposit the aluminum oxide thin film on the front and back surfaces of the silicon wafer, and the thickness of the aluminum oxide thin film is 2 to 20 nm.

8. 2. The method for manufacturing a contact-passivated all-back electrode solar cell according to claim 1, wherein step S9 uses tube-type or plate-type PECVD to deposit the silicon nitride passivation film or the silicon nitride / silicon oxynitride stacked passivation film on the front and back surfaces of the silicon wafer, respectively, and the passivation film has a thickness of 50-100 nm and a refractive index of 1.9-2.

4.

9. The method for manufacturing a contact-passivated all back contact solar cell according to claim 1, wherein the sintering temperature in step S11 is 700-900°C.

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