TOPCon battery and preparation process of phosphorus-doped polycrystalline silicon of TOPCon battery

Abstract

The invention discloses a TOPCon cell and a preparation process of phosphorus-doped polycrystalline silicon of the TOPCon cell, and relates to the technical field of solar cells. The method comprises the following steps: S1, preorder steps; s2, a PECVD (plasma enhanced chemical vapor deposition) coating process; s3, a diffusion process; s4, high-temperature annealing; compared with the prior art, the preparation process of the phosphorus-doped polycrystalline silicon of the TOPCon battery has the advantages that the problem of winding plating can be effectively solved, and the phosphorus activity doping concentration in the polycrystalline silicon is improved on the premise that the flow of phosphorane is not increased, so that the structure and the efficiency of the TOPCon battery are improved; the problem that phosphorus activity is reduced after doping when a Poly-Si layer is prepared on a silicon substrate through the PECVD technology is solved.

Description

Technical Field

[0001] The invention relates to the technical field of solar cell sheets, and in particular to a preparation process of phosphorus-doped polycrystalline silicon of a TOPCon cell. Background Art

[0002] TOPCon solar cells are made by first preparing a tunneling oxide layer on the back of the cell, and then depositing a layer of doped polysilicon. The two together form a passivation contact structure, providing good interface passivation for the back of the silicon wafer.

[0003] Among the existing documents, patent CN 115692545 A discloses a method for increasing the active phosphorus doping concentration of polycrystalline silicon of N-type TOPCon cells in the PECVD route. It discloses the use of PECVD technology to grow a tunneling oxide layer on the back of a silicon wafer. After the tunneling oxide layer is grown, the PECVD technology is continued to be used to deposit a phosphorus-doped amorphous silicon film with a gradually increasing phosphorus doping concentration on the surface of the tunneling oxide layer, and the phosphorus-doped amorphous silicon film obtained in step (3) is crystallized and phosphorus diffused. It is also recorded that compared with conventional processes, the combined process of "PECVD in-situ doping + phosphorus diffusion doping annealing process" used in the present invention is more conducive to obtaining polycrystalline silicon with a high surface doping concentration.

[0004] Based on the search of the above patents and combined with the equipment in the prior art, it is found that the tunneling oxide passivation contact (TOPCon) solar cell has occupied the main market of the industry due to its advantages such as high theoretical limit photoelectric conversion efficiency, easy availability of raw materials, high reliability, and low light decay. It has a "back tunneling oxide layer + phosphorus-doped polysilicon layer" structure. The main technical routes of this structure are low-pressure chemical vapor deposition (LPCVD) and plasma enhanced chemical vapor deposition (PECVD). Among them, the LPCVD technology is to first prepare intrinsic amorphous silicon, and then perform a high-temperature phosphorus diffusion process. While phosphorus doping is being performed, the amorphous silicon is crystallized into polycrystalline silicon, thereby realizing the preparation of phosphorus-doped polycrystalline silicon. Although it has the highest maturity, it has serious The heavy polysilicon winding plating and quartz reduction loss problems, high production cost and low production efficiency. Although PECVD technology can improve the winding plating problem, one of the most serious problems is the low phosphorus active doping concentration of polysilicon. Although this problem can be improved by increasing the phosphine flow rate, it will not only increase the cost, but also the thermal diffusion of phosphorus atoms in the high-temperature annealing crystallization activation process will cause greater damage to the tunneling oxide layer. Therefore, we invented a new phosphorus-doped Poly-Si preparation process, which can solve the problem of reduced phosphorus activity after doping encountered when using PECVD technology to prepare Poly-Si layer on silicon substrate. For this reason, a preparation process of phosphorus-doped polysilicon for TOPCon battery is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a preparation process for phosphorus-doped polysilicon of a TOPCon cell, and solve the following technical problems: the phosphorus active doping concentration of polysilicon is low. Although this problem can be improved by increasing the phosphine flow rate, it will not only increase the cost, but also the thermal diffusion of phosphorus atoms in the high-temperature annealing crystallization activation process will cause greater damage to the tunneling oxide layer. By using a tubular diffusion machine to perform high-temperature phosphorus diffusion on silicon wafers, intrinsic amorphous silicon is converted into phosphorus-doped polysilicon, which can effectively improve the winding plating problem and increase the phosphorus active doping concentration in polysilicon without increasing the phosphine flow rate, thereby improving the structure and efficiency of the TOPCon cell. A preparation process for phosphorus-doped polysilicon of a TOPCon cell is proposed.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A process for preparing phosphorus-doped polysilicon for a TOPCon cell, comprising the following steps:

[0008] S1. Pre-treat the silicon wafer to obtain a pre-treated silicon wafer.

[0009] S2, PECVD coating process. After the front-end texturing, alkali polishing and other processes, the silicon wafer is sent to the PECVD machine for coating. First, nitrous oxide is introduced into the PECVD machine to use the oxidizing property of laughing gas to generate a tunneling silicon dioxide oxide layer on the back of the silicon wafer. After this step is completed, silane and hydrogen are introduced into the oxide layer to react and generate intrinsic amorphous silicon, and then it is moved out of the PECVD machine and entered into the phosphorus diffusion equipment.

[0010] S3, diffusion process. In the phosphorus diffusion equipment, oxygen is first introduced to grow an oxide layer on the intrinsic amorphous silicon, and then oxygen, phosphorus oxychloride and nitrogen are introduced simultaneously to convert the oxide layer on the intrinsic amorphous silicon into PSG, and preliminary phosphorus diffusion is performed.

[0011] S4, high temperature annealing. After the diffusion process, a high temperature annealing process is performed, in which phosphorus oxychloride and oxygen are turned off and only nitrogen is introduced for high temperature annealing, so as to convert intrinsic amorphous silicon into polycrystalline silicon, and at the same time, a phosphorus source is doped to obtain phosphorus-doped polycrystalline silicon.

[0012] S5. Post-process the obtained phosphorus-doped polycrystalline silicon to obtain a TOPCon cell of phosphorus-doped polycrystalline silicon.

[0013] As a further solution of the present invention: in said S1, the preceding steps include texturing, boron diffusion, BSG removal and alkali polishing processes, wherein the texturing process: cleans the damage on the surface of the silicon wafer, removes metal impurities and oil stains on the surface. A tiny uneven surface velvet structure is prepared on the surface of the silicon wafer to reduce the reflectivity of the incident light on the surface of the silicon wafer and increase the absorption and utilization of light by the silicon wafer.

[0014] Boron diffusion is the process of doping and diffusing boron on an N-type silicon wafer to form a semiconductor device with a PN junction structure.

[0015] BSG removal and alkaline polishing: After boron diffusion, a layer of BSG will be generated on the surface of the silicon wafer. A certain concentration of acid is used to react with the back of the silicon wafer to remove the BSG on the front of the silicon wafer and the PN junction on the back and edge.

[0016] As a further solution of the present invention: in said S5, the post-processing steps of the obtained phosphorus-doped polysilicon include PSG removal, RCA, passivation, screen, and test sorting, wherein, PSG removal: using a certain concentration of acid to chemically react with the PSG layer on the back of the silicon wafer, thereby etching away the layer. RCA: After completing the above processes, the RCA cleaning technology is mainly used to remove particles and metal impurities on the surface of the silicon wafer, improve the problems of winding plating and edge leakage, and improve the efficiency and stability of the battery.

[0017] Passivation: Passivation includes coating of aluminum oxide film, positive film and back film, etc., which mainly plays the role of protecting the silicon wafer. There are a large number of hydrogen bonds in the film, which can combine with the dangling bonds on the surface or inside of the silicon wafer to form a stable structure, which plays a role of passivation. At the same time, it reduces the reflectivity of the silicon wafer surface and further increases the absorption of incident light.

[0018] Silk screen: The silk screen process is mainly used to make the positive and back electrodes of the battery. The main function of the positive and back electrodes is to lead the photocurrent in the battery. Silver paste is usually used in its production, which has low resistance.

[0019] As a further solution of the present invention: in S3, the phosphorus diffusion equipment includes a diffusion furnace body, a diffusion furnace door is hingedly installed on the port of the diffusion furnace body, and a pressure gauge for measuring pressure is installed on the diffusion furnace body.

[0020] A supporting pipe network is provided inside the diffusion furnace body, and a diffusion furnace inner cover is provided inside the diffusion furnace inner cover. A supporting pipe network is provided inside the diffusion furnace inner cover.

[0021] A pressure limiting structure is installed on the outer side of the diffusion furnace body, and the pressure limiting structure is connected to the inner cover of the diffusion furnace through a conduit.

[0022] The movable cylinder, the pressure limiting structure includes a movable cylinder, the movable cylinder is fixed on the outside of the diffusion furnace body, a piston is arranged inside the movable cylinder, an "L"-shaped air guide hole is arranged inside the piston, and a scale line corresponding to the pressure value is arranged on the outside of the movable cylinder.

[0023] A spring is fixedly connected between the piston and the inner wall of one end of the movable cylinder.

[0024] As a further solution of the present invention: the pressure limiting structure also includes a movable sealing plate, one end of the air guide hole on the piston is connected to an air pipe, a sliding slot is provided on the movable cylinder, and the air pipe slides inside the sliding slot.

[0025] As a further solution of the present invention: a movable sealing plate is arranged on the outer side of the movable cylinder, and a movable air hole is opened on the movable sealing plate, and the movable air hole is connected to the air pipe.

[0026] As a further solution of the present invention: a movable cover is arranged on the outside of the movable cylinder, a slide groove is arranged inside the movable cover, the movable sealing plate is slidably arranged in the slide groove inside the movable cover, an exhaust hole is arranged on the movable cover, and the exhaust hole is connected with an exhaust pipe. Scale lines required for different pressure values ​​are arranged on the outside of the movable cylinder to better adjust the position of the movable cover. After detection, a graphite boat carrying silicon wafers is placed in the movable cover, and the sliding of the movable cover can be achieved by loosening the locking screw. The movable cover is adjusted to the required pressure value position in the cavity, and the movable cover is fixed by tightening the end of the locking screw against the outside of the movable cylinder, when the reaction gas is introduced through the air inlet pipe.

[0027] As the internal air pressure increases, the piston is gradually squeezed.

[0028] The piston will slide in the movable cylinder to squeeze the spring. During the sliding process of the piston, with the cooperation of the air pipe, the movable sealing plate will be driven to slide in the slide groove inside the movable cover. When the movable air hole slides to the exhaust hole on the outside of the movable cover, the internal gas will be transported. At this time, it means that the internal reaction gas pressure meets the standard. Secondly, when the air pressure is higher than the set air pressure, the movable air hole and the exhaust hole overlap to achieve exhaust, thereby ensuring the stability of the internal reaction gas pressure, ensuring that the air pressure is stable during the diffusion process, and the diffusion effect is better.

[0029] As a further solution of the present invention: a movable rod is fixed on one side of the piston, one end of the movable rod passes through one end of the movable cylinder, a first electrode block is fixed to one end of the movable rod, a connecting rod is connected to the movable cover, a movable electrode sheet is arranged on the connecting rod, the first electrode block is in tangential contact with the movable electrode sheet after movement, a fixed block is installed on the exhaust pipe, a warning light is installed on the fixed block, the movable electrode sheet, the first electrode block, the warning light and the power supply are connected to form a circuit, when the sealing of the inside of the furnace body is detected, by setting a monitoring quantity, after the first electrode block and the movable electrode sheet are in contact, the warning light is energized, and during the static time, the sealing effect of the furnace body is judged by the flashing state of the warning light.

[0030] As a further solution of the present invention: a fixed ring is provided on the outer side of the middle part of the supporting pipe network, a rotating ring is rotatably mounted on the outer side of the fixed ring, blades are respectively fixed on both sides of the rotating ring, a wind plate is installed on the outer side surface of the rotating ring, a fixed frame is fixed on the inner cover of the diffusion furnace, an air hood is installed on the fixed frame, cutouts for air plates to pass through are provided on both sides of the air hood, and an air inlet pipe is connected to the top of the air hood.

[0031] A TOPCon cell, wherein phosphorus-doped polycrystalline silicon of the TOPCon cell is prepared by a preparation process of phosphorus-doped polycrystalline silicon of the TOPCon cell.

[0032] Beneficial effects of the present invention:

[0033] The invention discloses a preparation process of phosphorus-doped polysilicon of a TOPCon cell, wherein intrinsic amorphous silicon is prepared by a PECVD process, and a tubular diffusion machine is used to perform high-temperature phosphorus diffusion on a silicon wafer, so that the intrinsic amorphous silicon is converted into phosphorus-doped polysilicon, which can effectively improve the winding plating problem and increase the phosphorus active doping concentration in the polysilicon without increasing the phosphine flow rate, thereby improving the structure and efficiency of the TOPCon cell and solving the problem of reduced phosphorus activity after doping encountered when using the PECVD technology to prepare a Poly-Si layer on a silicon substrate

[0034] During the experiment, by setting up a pressure-limiting structure, the pressure value detected by the pressure-limiting structure depends on the deformation of the spring, and the pressure of the piston can be known according to the elastic coefficient. During the test, by pausing the intake and exhaust for a short time, and waiting, if the power-on state of the warning light does not change, it means that the sealing of the diffusion furnace meets the requirements.

[0035] After the test, the graphite boat carrying the silicon wafer is placed in the chamber, and the movable cover is adjusted to the required pressure value position in the chamber. As the internal air pressure increases, the piston is gradually squeezed. When the movable air hole slides to the exhaust hole on the outside of the movable cover, the internal gas is transported. At this time, it indicates that the internal reaction gas pressure is marked. Secondly, when the air pressure is higher than the set air pressure, the movable air hole 113 overlaps with the exhaust hole to achieve exhaust, thereby ensuring the stability of the internal reaction gas pressure, ensuring that the air pressure is stable during the diffusion process, and the diffusion effect is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below in conjunction with the accompanying drawings.

[0037] Figure 1 It is a schematic diagram of the process flow of the present invention.

[0038] Figure 2 This is the overall structure diagram of the diffusion furnace

[0039] Figure 3 This is a diagram of the internal structure of a diffusion furnace.

[0040] Figure 4 This is the structural diagram of the internal support network of the diffusion furnace.

[0041] Figure 5 This is a top view of the diffusion furnace structure.

[0042] Figure 6 yes Figure 5 Structural diagram cut along AA in the middle.

[0043] Figure 7 This is the external structure diagram of the movable cylinder.

[0044] Figure 8 This is a diagram of the trachea location structure.

[0045] Fig. 9 The internal structure of the movable cylinder

[0046] Legend:

[0047] 1. Diffusion furnace door, 2. Diffusion furnace body, 3. Support pipe network, 4. Pressure gauge, 5. Air inlet pipe, 6. Exhaust pipe, 7. Diffusion furnace inner cover, 8. Gas hood, 9. Fixed block, 10. Warning light, 11. Pressure limiting structure, 12. Fixed ring, 13. Rotating ring, 14. Wind plate, 15. Fixed frame, 16. Blade, 101. Movable cover, 102. Locking screw, 103. Connecting rod, 104. Movable electrode sheet, 105. First electrode block, 106. Movable rod, 107. Movable cylinder, 108. Spring, 109. Sliding slot, 110. Air pipe, 111. Piston, 112. Air inlet, 113. Movable air hole, 114. Movable sealing plate. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] like Figure 1 As shown, the present invention is a process for preparing phosphorus-doped polycrystalline silicon of a TOPCon cell, comprising:

[0050] S1. Preliminary step: pre-treating the silicon wafer to obtain a pre-treated silicon wafer.

[0051] S2, PECVD coating process: After the silicon wafer has gone through the processes of front-end texturing, alkali polishing, etc., it is sent to the PECVD machine for coating. First, nitrous oxide is introduced into the PECVD machine, and a tunneling silicon dioxide oxide layer is generated on the back of the silicon wafer by using the oxidizing property of laughing gas. After this step is completed, silane and hydrogen are introduced into the oxide layer to react and generate intrinsic amorphous silicon, and then it is moved out of the PECVD machine and entered into the phosphorus diffusion machine.

[0052] S3, diffusion process: In the phosphorus diffusion equipment, oxygen is first introduced to grow an oxide layer on the intrinsic amorphous silicon, and then oxygen, phosphorus oxychloride and nitrogen are introduced simultaneously to convert the oxide layer on the intrinsic amorphous silicon into PSG, and preliminary phosphorus diffusion is performed.

[0053] S4, high temperature annealing: After the diffusion process, a high temperature annealing process is performed, phosphorus oxychloride and oxygen are turned off and only nitrogen is introduced for high temperature annealing, the intrinsic amorphous silicon is converted into polycrystalline silicon, and a phosphorus source is doped at the same time to obtain phosphorus-doped polycrystalline silicon. This process is repeated twice to prepare a double-layer poly-Si layer and SiO2 layer.

[0054] S5. Subsequent steps: post-processing the obtained phosphorus-doped polycrystalline silicon to obtain a TOPCon cell of phosphorus-doped polycrystalline silicon.

[0055] In S1, the preceding steps include texturing, boron diffusion, BSG removal and alkali polishing, wherein the texturing process: cleans the damage on the surface of the silicon wafer, removes metal impurities and oil stains on the surface. A tiny uneven surface velvet structure is prepared on the surface of the silicon wafer to reduce the reflectivity of the incident light on the surface of the silicon wafer and increase the absorption and utilization of light by the silicon wafer.

[0056] Boron diffusion is the process of doping and diffusing boron on an N-type silicon wafer to form a semiconductor device with a PN junction structure.

[0057] BSG removal and alkaline polishing: After boron diffusion, a layer of BSG will be generated on the surface of the silicon wafer. A certain concentration of acid is used to react with the back of the silicon wafer to remove the BSG on the front of the silicon wafer and the PN junction on the back and edge.

[0058] In S5, the subsequent steps include PSG removal, RCA, passivation, silk screen, and test sorting, wherein PSG removal: using a certain concentration of acid to chemically react with the PSG layer on the back of the silicon wafer, thereby etching away the layer. RCA: After completing the above processes, the RCA cleaning technology is mainly used to remove particles and metal impurities on the surface of the silicon wafer, improve problems such as wrapping plating and edge leakage, and improve the efficiency and stability of the battery.

[0059] Passivation: Passivation includes coating of aluminum oxide film, positive film and back film, etc., which mainly plays the role of protecting the silicon wafer. There are a large number of hydrogen bonds in the film, which can combine with the dangling bonds on the surface or inside of the silicon wafer to form a stable structure, which plays a role of passivation. At the same time, it reduces the reflectivity of the silicon wafer surface and further increases the absorption of incident light.

[0060] Silk screen: The silk screen process is mainly used to make the positive and back electrodes of the battery. The main function of the positive and back electrodes is to lead the photocurrent in the battery. Silver paste is usually used in its production, which has low resistance.

[0061] A TOPCon cell, wherein phosphorus-doped polycrystalline silicon of the TOPCon cell is prepared by a preparation process of phosphorus-doped polycrystalline silicon of the TOPCon cell.

[0062] like Figure 2-9 As shown, in S3, the phosphorus diffusion equipment includes a diffusion furnace body 2, a diffusion furnace door 1 is hingedly installed on the port of the diffusion furnace body 2, and a pressure gauge 4 for measuring pressure is installed on the diffusion furnace body 2.

[0063] The diffusion furnace body 2 is provided with a diffusion furnace inner cover 7 , and the diffusion furnace inner cover 7 is provided with a support pipe network 3 .

[0064] A pressure limiting structure 11 is installed on the outer side of the diffusion furnace body 2, and the pressure limiting structure 11 is connected to the diffusion furnace inner cover 7 through a conduit.

[0065] The movable cylinder 107 , the pressure limiting structure 11 comprises the movable cylinder 107 , the movable cylinder 107 is fixed on the outside of the diffusion furnace body 2 , a piston 111 is arranged inside the movable cylinder 107 , and an “L”-shaped air guide hole is arranged inside the piston 111 .

[0066] Spring 108 , a spring 108 is fixedly connected between the piston 111 and the inner wall of one end of the movable cylinder 107 .

[0067] The pressure limiting structure 11 further includes a movable sealing plate 114 . One end of the air guide hole on the piston 111 is connected to an air pipe 110 . The movable cylinder 107 is provided with a sliding slot 109 . The air pipe 110 is slidably provided inside the sliding slot 109 .

[0068] A movable sealing plate 114 is disposed on the outer side of the movable cylinder 107 . A movable air hole 113 is formed on the movable sealing plate 114 . The movable air hole 113 is communicated with the air pipe 110 .

[0069] A movable cover 101 is arranged outside the movable cylinder 107, a slide groove is arranged inside the movable cover 101, the movable sealing plate 114 is slidably arranged in the slide groove inside the movable cover 101, an exhaust hole is arranged on the movable cover 101, and an exhaust pipe 6 is connected to the exhaust hole.

[0070] A movable rod 106 is fixed to one side of the piston 111, one end of which passes through one end of a movable cylinder 107, and a first electrode block 105 is fixed to one end of the movable rod 106. A connecting rod 103 is connected to the movable cover 101, and a movable electrode sheet 104 is provided on the connecting rod 103.

[0071] The first electrode block 105 is in tangential contact with the movable electrode sheet 104 after movement. A fixed block 9 is installed on the exhaust pipe 6. A warning light 10 is installed on the fixed block 9. The movable electrode sheet 104, the first electrode block 105, the warning light 10 and the power supply are connected to form a circuit.

[0072] A fixed ring 12 is provided on the outer side of the middle part of the supporting pipe network 3, and a rotating ring 13 is rotatably mounted on the outer side of the fixed ring 12. Blades 16 are respectively fixed on both sides of the rotating ring 13, and a wind plate 14 is installed on the outer side of the rotating ring 13. A fixed frame 15 is fixed on the inner cover 7 of the diffusion furnace, and an air hood 8 is installed on the fixed frame 15. Cutouts for the air supply plates 14 to pass through are provided on both sides of the air hood 8, and an air inlet pipe 5 is connected to the top of the air hood 8.

[0073] In order to perform stable diffusion annealing on the battery cell.

[0074] It is necessary to ensure the sealing effect of the diffusion furnace body 2 after air intake. After closing the diffusion furnace door 1, adjust the position of the movable cover 101, and with the cooperation of the connecting rod 103, adjust the position of the movable electrode sheet 104 to the position of the detection pressure, and let air into the diffusion furnace body 2 through the air intake pipe 5. During the air intake process, the internal pressure is visually detected by the pressure gauge 4. When the internal gas is pressurized, as the internal pressure increases, the piston 111 can be pushed to slide inside the movable cylinder 107 to compress the spring 108, and at the same time, the movable rod 106 is pushed outward, so that the first electrode block 105 can move toward the adjusted movable electrode sheet 104. When the detection pressure environment is reached, the first electrode block 105 contacts the movable electrode sheet 104, and after contact, the warning light 10 is powered on.

[0075] At the same time, the pressure value set by the pressure detection is compared with the pressure value directly detected by the pressure gauge 4 to see if they are consistent, and they are calibrated against each other.

[0076] The pressure value detected by the pressure-limiting structure 11 depends on the deformation of the spring 108 , and the pressure of the piston 111 can be obtained according to the elastic coefficient.

[0077] During the inspection, the air intake and exhaust are suspended for a short period of time, and if the power-on state of the warning light 10 does not change, it means that the sealing of the diffusion furnace meets the requirements.

[0078] After the inspection, the graphite boat carrying the silicon wafer is placed in, and the sliding of the movable cover 101 can be achieved by loosening the locking screw 102. The movable cover 101 is adjusted to the required pressure value position in the cavity, and the movable cover 101 is fixed by tightening the end of the locking screw 102 against the outside of the movable cylinder 107, when the reaction gas is introduced through the air inlet pipe 5.

[0079] As the internal air pressure increases, the piston 111 is gradually squeezed.

[0080] The piston 111 will slide in the movable cylinder 107 to squeeze the spring 108. During the sliding of the piston 111, with the cooperation of the air pipe 110, the movable sealing plate 114 will be driven to slide in the slide groove inside the movable cover 101. When the movable air hole 113 slides to the exhaust hole on the outside of the movable cover 101, the internal gas is transported. At this time, it means that the internal reaction gas pressure is marked. Secondly, when the air pressure is higher than the set air pressure, the movable air hole 113 overlaps with the exhaust hole to achieve exhaust, thereby ensuring the stability of the internal reaction gas pressure. During the diffusion process, the air pressure is stable and the diffusion effect is better.

[0081] During the air intake process, when air is taken in through the air intake pipe 5, the impulse generated by the air intake through the air intake pipe 5 acts on the wind plate 14, which can drive the rotating ring 13 to rotate. When the rotating ring 13 rotates, it can drive the blades 16 to rotate on the outside of the supporting pipe network 3, which can better diffuse the air intake, ensure the internal gas balance, and better realize the reaction of silicon wafers at different positions in the diffusion furnace.

[0082] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. An embodiment of the present invention is described in detail above, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equal changes and improvements made according to the scope of application of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A process for preparing phosphorus-doped polysilicon for TOPCon cells, characterized in that the steps include: S1, pre-treating the silicon wafer to obtain a pre-treated silicon wafer; S2, PECVD coating process; The pre-treated silicon wafer is sent to the PECVD machine for coating. First, nitrous oxide is introduced into the PECVD machine to generate a tunneling silicon dioxide oxide layer on the back of the silicon wafer using the oxidizing property of laughing gas. After completion, silane and hydrogen are introduced into the oxide layer to react and generate intrinsic amorphous silicon. After that, the PECVD machine is removed and entered into the phosphorus diffusion equipment. S3, diffusion process: In the phosphorus diffusion equipment, oxygen is first introduced to grow an oxide layer on the intrinsic amorphous silicon, and then oxygen, phosphorus oxychloride and nitrogen are introduced simultaneously to convert the oxide layer on the intrinsic amorphous silicon into PSG, and preliminary phosphorus diffusion is performed; S4, high temperature annealing; after the diffusion process, a high temperature annealing process is performed, phosphorus oxychloride and oxygen are turned off and only nitrogen is introduced for high temperature annealing, the intrinsic amorphous silicon is converted into polycrystalline silicon, and a phosphorus source is doped at the same time to obtain phosphorus-doped polycrystalline silicon; S5. Post-process the obtained phosphorus-doped polycrystalline silicon to obtain a TOPCon cell of phosphorus-doped polycrystalline silicon.

2. The process for preparing phosphorus-doped polycrystalline silicon of a TOPCon cell according to claim 1, characterized in that: In S1, the pre-treatment steps for the silicon wafer include texturing, boron diffusion, BSG removal and alkali polishing processes, wherein the texturing process: cleans the damage on the surface of the silicon wafer, removes metal impurities and oil stains on the surface; prepares a tiny uneven surface texture structure on the surface of the silicon wafer, reduces the reflectivity of the incident light on the surface of the silicon wafer, and increases the absorption and utilization of light by the silicon wafer; Boron diffusion is to dope and diffuse B on N-type silicon wafer to form a semiconductor device with a PN junction structure. BSG removal and alkaline polishing: After boron diffusion, a layer of BSG will be generated on the surface of the silicon wafer. A certain concentration of acid is used to react with the back of the silicon wafer to remove the BSG on the front of the silicon wafer and the PN junction on the back and edge.

3. The process for preparing phosphorus-doped polycrystalline silicon of a TOPCon cell according to claim 1, characterized in that: In S5, the post-processing steps of the obtained phosphorus-doped polysilicon include PSG removal, RCA, passivation and screen, wherein PSG removal: using an acid solution of a certain concentration to chemically react with the PSG layer on the back of the silicon wafer, thereby etching away the layer; RCA: after completing the above processes, the RCA cleaning technology is mainly used to remove particles and metal impurities on the surface of the silicon wafer, improve the problems of winding plating and edge leakage, and improve the efficiency and stability of the battery; Passivation: Passivation includes aluminum oxide coating, positive film coating, back film coating, etc., which mainly protects the silicon wafer. There are a large number of hydrogen bonds in the film, which can combine with the dangling bonds on the surface or inside of the silicon wafer to form a stable structure, which plays a role in passivation. At the same time, it reduces the reflectivity of the silicon wafer surface and further increases the absorption of incident light. Silk screen: The silk screen process is mainly used to make the positive and back electrodes of the battery. The main function of the positive and back electrodes is to lead the photocurrent in the battery. Silver paste is usually used in its production, which has low resistance.

4. The process for preparing phosphorus-doped polycrystalline silicon of a TOPCon cell according to claim 1, characterized in that: In S3, the phosphorus diffusion equipment comprises a diffusion furnace body (2), a diffusion furnace door (1) is hingedly mounted on a port of the diffusion furnace body (2), and a pressure gauge (4) for measuring pressure is mounted on the diffusion furnace body (2); A supporting pipe network (3), wherein a diffusion furnace inner cover (7) is arranged inside the diffusion furnace body (2), and a supporting pipe network (3) is arranged inside the diffusion furnace inner cover (7); A pressure limiting structure (11), wherein the outer side of the diffusion furnace body (2) is provided with a pressure limiting structure (11), and the pressure limiting structure (11) is connected to the diffusion furnace inner cover (7) via a conduit; A movable cylinder (107), the pressure limiting structure (11) comprising a movable cylinder (107), the movable cylinder (107) being fixed on the outside of the diffusion furnace body (2), a piston (111) being arranged inside the movable cylinder (107), an "L"-shaped air guide hole being arranged inside the piston (111), and a scale line corresponding to the pressure value being arranged on the outside of the movable cylinder (107); A spring (108) is fixedly connected between the piston (111) and the inner wall of one end of the movable cylinder (107).

5. The process for preparing phosphorus-doped polycrystalline silicon of a TOPCon cell according to claim 1, characterized in that: The pressure limiting structure (11) further comprises a movable sealing plate (114); one end of the air guide hole on the piston (111) is connected to an air pipe (110); a sliding slot hole (109) is provided on the movable cylinder (107); and the air pipe (110) is slidably provided inside the sliding slot hole (109).

6. The process for preparing phosphorus-doped polycrystalline silicon of a TOPCon cell according to claim 1, characterized in that: A movable sealing plate (114) is arranged on the outer side of the movable cylinder (107), and a movable air hole (113) is opened on the movable sealing plate (114), and the movable air hole (113) is communicated with the air pipe (110).

7. The process for preparing phosphorus-doped polycrystalline silicon of a TOPCon cell according to claim 1, characterized in that: A movable cover (101) is arranged outside the movable cylinder (107), a slide groove is arranged inside the movable cover (101), the movable sealing plate (114) is slidably arranged in the slide groove inside the movable cover (101), an exhaust hole is arranged on the movable cover (101), and an exhaust pipe (6) is connected to the exhaust hole.

8. The process for preparing phosphorus-doped polycrystalline silicon of a TOPCon cell according to claim 1, characterized in that: A movable rod (106) is fixed to one side of the piston (111), one end of the movable rod (106) passes through one end of a movable cylinder (107), a first electrode block (105) is fixed to one end of the movable rod (106), a connecting rod (103) is connected to the movable cover (101), and a movable electrode sheet (104) is provided on the connecting rod (103); The first electrode block (105) comes into tangential contact with the movable electrode sheet (104) after movement; a fixed block (9) is mounted on the exhaust pipe (6); a warning light (10) is mounted on the fixed block (9); and the movable electrode sheet (104), the first electrode block (105), the warning light (10) and a power source are connected to form a circuit.

9. The process for preparing phosphorus-doped polycrystalline silicon of a TOPCon cell according to claim 1, characterized in that: A fixed ring (12) is arranged on the outer side of the middle part of the supporting pipe network (3), a rotating ring (13) is rotatably mounted on the outer side of the fixed ring (12), blades (16) are respectively fixed on both sides of the rotating ring (13), a wind plate (14) is installed on the outer side surface of the rotating ring (13), a fixed frame (15) is fixed on the inner cover (7) of the diffusion furnace, an air hood (8) is installed on the fixed frame (15), cutouts for the air supply plates (14) to pass through are arranged on both sides of the air hood (8), and an air inlet pipe (5) is connected to the top of the air hood (8).

10. A TOPCon battery, characterized in that: The phosphorus-doped polycrystalline silicon of the TOPCon cell is prepared by the preparation process of the phosphorus-doped polycrystalline silicon of the TOPCon cell according to any one of claims 1-9.

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