A TOPCon battery, preparation method and equipment

Abstract

The present invention discloses a TOPCon battery, preparation method and equipment, including S1: placing a silicon wafer to be processed into a texturing tank for double-sided texturing; S2: performing boron diffusion on the front side of the silicon wafer obtained by S1; S3: performing SE laser heavy doping on the fine grid line position on the front side of the silicon wafer obtained by S2; S4: performing surface oxidation treatment on the silicon wafer obtained by S3 to form BSG; S5: performing BSG removal and alkali polishing treatment on the back side of the silicon wafer obtained by S4; S6: using PECVD to perform tunneling oxide layer and doped amorphous silicon deposition on the back side of the silicon wafer obtained by S5; S7: performing annealing and crystallization treatment on the silicon wafer obtained by S6. The present invention adds a step of removing AlOx winding plating after depositing AlOx film on the front side of the silicon wafer, and specifically utilizes that in the process of rolling and conveying the silicon wafer by a roller, the lower part of the roller is immersed in the reaction solution, so that the reaction solution can be attached and then contacted with the back side of the silicon wafer to achieve corrosion and de-winding plating, so that the appearance of the back side of the obtained silicon wafer is improved and the contact resistance is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of crystalline silicon cell manufacturing, and in particular to a TOPCon cell, a preparation method and equipment. Background Art

[0002] In order to improve the equipment capacity utilization rate, the TOPCon aluminum oxide deposition process uses a single-slot double-insert method, that is, two silicon wafers are pasted back to back to deposit single-sided aluminum oxide. However, in the actual process, due to the poor fit between the wafers, aluminum oxide is easily plated around to the back of the silicon wafer, resulting in poor appearance and high back contact resistance.

[0003] Patent document CN117107214A, announced on November 24, 2023, discloses a method for reducing the wrap-around plating of aluminum oxide film prepared by TOPCon cells, so that when the aluminum oxide film is deposited on the front of the silicon substrate using ALD equipment, in the second reaction, water vapor and ozone are used alternately as precursors, and under the joint action of a water vapor amount ranging from 30-70%, the wrap-around plating range can be reduced to 6-7mm, and the conversion efficiency is 24.957-25.03%; thereby, on the basis of ensuring the conversion efficiency of the battery cell, reducing the color difference of the appearance edge, reducing the differences in the slurry and sintering on the back of the silicon substrate, and avoiding the risk of poor EL.

[0004] At present, in order to improve and solve the problem of back-side plating, the TOPCon alumina deposition process mainly adopts a single-slot single-insert method, which can achieve double-sided alumina, and then match the back side with a back slurry that enhances the burn-through property. In this way, the consistency of the back side appearance is better, but the loss of production capacity is too much. Therefore, there is also a method of reducing the slot spacing of the aluminum boat and then superimposing a single slot single-insert method to make up for some of the production capacity loss. However, when the slot spacing is reduced, the uniformity of alumina deposition on the silicon wafer surface becomes worse. Therefore, there is an urgent need for a TOPCon battery, preparation method and equipment to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a TOPCon battery, a preparation method and an apparatus to solve the above-mentioned deficiencies in the prior art.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A TOPCon battery preparation method comprises the following steps:

[0008] S1: Put the silicon wafer to be processed into the texturing tank for double-sided texturing to form a pyramid structure;

[0009] S2: Boron diffusion is performed on the front side of the silicon wafer obtained in S1, the boron source is BCl3, and the diffusion square resistance is 100-150ohm / sq;

[0010] S3: Perform SE laser heavy doping on the fine gate line position on the front side of the silicon wafer obtained in S2, and the sheet resistance of the heavily doped area is 70-80 ohm / sq;

[0011] S4: oxidizing the surface of the silicon wafer obtained in S3 to form BSG with a thickness of 80-120 nm and a sheet resistance of 250-350 ohm / sq;

[0012] S5: The back side of the silicon wafer obtained in S4 is subjected to BSG removal and alkali polishing, and the obtained back side reflectivity is greater than 40%, and the tower base is greater than 6um;

[0013] S6: using PECVD to deposit a tunneling oxide layer and doped amorphous silicon on the back of the silicon wafer obtained in S5, the thickness of the ultra-thin oxide layer is 1-1.8nm, the thickness of the doped amorphous silicon layer is 80-130nm, and the thickness of the outer mask layer silicon oxide is 100-150nm;

[0014] S7: performing annealing and crystallization treatment on the silicon wafer obtained in S6, so that the doped amorphous silicon is crystallized into a doped polysilicon film, the doped square resistance is 30-80 ohm / sq, and the annealing temperature is 650-950° C.;

[0015] S8: The silicon wafer obtained in S7 is cleaned by a tank RCA to remove the poly silicon plating on the edge and the front, and the front BSG layer is cleaned by an HF acid tank to retain a certain thickness of silicon oxide on the back mask layer;

[0016] S9: depositing a layer of AlOx film on the front side of the silicon wafer obtained in S8 by ALD, with a thickness of 3-8 nm;

[0017] S10: removing AlOx coating from the back of the silicon wafer obtained in S9;

[0018] S11: depositing a silicon nitride layer on the front and back sides of the silicon wafer obtained in S10, wherein the thickness of the silicon nitride film on the front side is 60-90 nm, and the refractive index is 2.0-2.10, and the thickness of the silicon nitride film on the back side is 70-90 nm, and the refractive index is 2.05-2.15;

[0019] S12: Printing silver paste on the front and back sides of the silicon wafer obtained in S10.

[0020] Preferably, a chain machine is used in S5, and the front side of the silicon wafer is protected by a water film, and the BSG on the back and four sides of the silicon wafer is removed by using a 28%-35% by volume HF solution and a roller with liquid; after removing the BSG, a slot machine is used to perform alkaline polishing on the rear surface of the silicon wafer, and the reaction liquid is an alkaline solution and a polishing agent, and the reaction is carried out at 60-70°C for 200s, and the BSG on the front side is retained.

[0021] Preferably, a chain machine is used in S10, and the front side of the silicon wafer is protected by a water film, and the AlOx film layer plated on the back side of the silicon wafer is selectively corroded with a 2%-30% HNO3 solution, and then a 5%-35% HF solution is used to remove the mask layer silicon oxide on the back side of the silicon wafer.

[0022] Preferably, in S10, the silicon wafer is conveyed by rollers, and water is dripped onto the front surface of the silicon wafer by a spray device to form a water film; the amount of water on the upper surface of the silicon wafer is 5-8 mg.

[0023] Preferably, the silicon wafer in S10 is conveyed to the HNO3 tank by rollers, and the bottom of the roller is immersed in the HNO3 solution in the HNO3 tank. During the rotation of the roller with liquid, the bottom of the silicon wafer contacts the HNO3 solution on the roller to remove AlOx plated on the back of the silicon wafer; the liquid level of the HNO3 solution is at 1 / 3 to 2 / 3 of the roller diameter, and the temperature of the HNO3 solution is 5-10°C.

[0024] Preferably, the silicon wafer in S10 is conveyed by rollers, passes through the HNO3 tank, and then continues to be conveyed to the HF tank. The bottom of the roller is immersed in the HF solution in the HF tank. During the rotation of the roller with liquid, the bottom of the silicon wafer contacts the HF solution on the roller to remove the mask layer silicon oxide on the back of the silicon wafer; the HF solution level is at 1 / 3 to 2 / 3 of the roller diameter, and the temperature of the HF solution is 20-30°C.

[0025] Preferably, the silicon wafer in S10 is conveyed by rollers, passes through a HNO3 tank and an HF tank, and then the upper and lower surfaces of the silicon wafer are rinsed with deionized water, and then the silicon wafer is dried.

[0026] A TOPCon battery is manufactured based on the above-mentioned preparation method, including a silicon wafer obtained by S12.

[0027] A device, based on the above-mentioned preparation method, is used for removing AlOx plating on the back side of a silicon wafer in S10, comprising a cell body, wherein a plurality of rollers are arranged in the cell body, wherein the cell body is loaded with a reaction solution, and the liquid level of the reaction solution is set at a position of 1 / 3 to 2 / 3 of the roller diameter.

[0028] Preferably, the roller is arranged in a liftable manner in the pool body, and the side wall of the pool body is provided with an undulating component for driving the roller to reciprocate and rise and fall. Along the conveying direction of the roller to the silicon wafer, among every three adjacent rollers, the roller close to the end in the conveying direction of the silicon wafer first rises and then resets, and at the same time, the roller close to the end in the conveying direction of the silicon wafer first descends and then resets.

[0029] In the above technical solution, the beneficial effects of the present invention are:

[0030] The TOPCon battery preparation method adds a step of removing the AlOx de-coating after depositing an AlOx film on the front side of the silicon wafer. Specifically, the lower part of the roller is immersed in the reaction solution during the process of the roller conveying the silicon wafer, so that it can be attached to the reaction solution and then contact the back side of the silicon wafer to achieve corrosion de-coating, thereby improving the appearance of the back side of the silicon wafer and reducing the contact resistance.

[0031] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

[0032] This application document provides an overview of various implementations or examples of the technology described in the present disclosure, and is not a comprehensive disclosure of the entire scope or all features of the disclosed technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0034] Figure 1 A schematic diagram of the overall structure of the device provided in an embodiment of the present invention;

[0035] Figure 2 A schematic cross-sectional view of the lifting compartment of the device provided in an embodiment of the present invention;

[0036] Figure 3 A schematic diagram of the structure of a series of devices used in S10 provided in an embodiment of the present invention;

[0037] Figure 4 A schematic diagram of a side cross-sectional structure of a device in which a group of rollers are in an ascending and descending state provided by an embodiment of the present invention;

[0038] Figure 5 A schematic diagram of a front cross-sectional structure of a device provided in an embodiment of the present invention;

[0039] Figure 6 The embodiment of the present invention provides Figure 5 A schematic diagram of the enlarged structure at A in the middle;

[0040] Figure 7 A schematic diagram of a side cross-sectional structure of a lifting compartment of a device provided by an embodiment of the present invention;

[0041] Figure 8 A schematic diagram of the side cross-sectional structure of a bracket of a device provided in an embodiment of the present invention.

[0042] Description of reference numerals:

[0043] 1. Pool body; 2. Roller; 3. Lifting bin; 4. Lifting arm; 5. Sliding block; 6. Slide groove; 7. Elastic member; 8. First rolling belt; 9. Second rolling belt; 10. Up and down block; 11. Lifting block; 12. Pressing block; 13. Bracket; 14. Transmission wheel; 15. Belt; 16. Driving rod; 17. Motor. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0045] Example 1

[0046] A TOPCon battery preparation method comprises the following steps:

[0047] S1: Put the silicon wafer to be processed into the texturing tank for double-sided texturing to form a pyramid structure;

[0048] S2: Boron diffusion is performed on the front side of the silicon wafer obtained in S1, the boron source is BCl3, and the diffusion square resistance is 100-150ohm / sq;

[0049] S3: Perform SE laser heavy doping on the fine gate line position on the front side of the silicon wafer obtained in S2, and the sheet resistance of the heavily doped area is 70-80 ohm / sq;

[0050] S4: The surface of the silicon wafer obtained in S3 is oxidized to form BSG with a thickness of 80-120nm and a sheet resistance of 250-350ohm / sq;

[0051] S5: Remove BSG and perform alkali polishing on the back of the silicon wafer obtained in S4, and the reflectivity of the back is greater than 40%, and the tower base is greater than 6um; use a chain machine, and under the protection of the front of the silicon wafer, use a HF solution with a volume ratio of 28%-35% and a roller belt liquid to remove BSG on the back and four sides of the silicon wafer; after removing BSG, use a slot machine to perform alkali polishing on the back surface of the silicon wafer, the reaction liquid is an alkali solution and a polishing agent, react at 60-70℃ for 200s, and the BSG on the front is retained; the alkali solution can be KOH or NaOH or an organic base;

[0052] S6: using PECVD to deposit a tunneling oxide layer and doped amorphous silicon on the back of the silicon wafer obtained in S5, the thickness of the ultra-thin oxide layer is 1-1.8nm, the thickness of the doped amorphous silicon layer is 80-130nm, and the thickness of the outer mask layer silicon oxide is 100-150nm;

[0053] S7: performing annealing and crystallization treatment on the silicon wafer obtained in S6, so that the doped amorphous silicon is crystallized into a doped polysilicon film, the doped square resistance is 30-80 ohm / sq, and the annealing temperature is 650-950° C.;

[0054] S8: The silicon wafer obtained in S7 is cleaned by a tank RCA to remove the poly silicon wrapping on the edge and the front, and the front BSG layer is cleaned by an HF acid tank, and a certain thickness of the back mask layer silicon oxide PSG is retained; an alkaline solution and additives are added to the RCA tank; the poly silicon wrapping is formed on the surface of the silicon wafer in S6. Doped amorphous silicon layer or outer mask layer silicon oxide;

[0055] S9: depositing a layer of AlOx film on the front side of the silicon wafer obtained in S8 by ALD, with a thickness of 3-8 nm;

[0056] S10: Remove AlOx coating on the back of the silicon wafer obtained in S9, use a chain machine, and under the protection of a water film on the front side of the silicon wafer, use a 2%-30% HNO3 solution to selectively etch the AlOx film layer coated on the back side of the silicon wafer, and then use a 5%-35% HF solution to remove the mask layer silicon oxide on the back side of the silicon wafer; the specific steps include: the silicon wafer is transported by roller 2, and water is dripped onto the front side of the silicon wafer by a spray device to form a water film; the amount of water on the upper surface of the silicon wafer is 5-8mg; then, the silicon wafer is transported to the HNO3 tank, and the bottom of the roller 2 is immersed in the HNO3 solution in the HNO3 tank. During the rotation of the roller 2 with liquid, the bottom of the silicon wafer contacts the HNO3 solution on the roller 2 to remove the AlOx coating on the back side of the silicon wafer. Ox; the HNO3 solution level is at 1 / 3 to 2 / 3 of the diameter of roller 2, the mass fraction of the HNO3 solution is 2%-30%, and the temperature of the HNO3 solution is 5-10°C; then, the silicon wafer continues to be transferred to the HF tank, and the bottom of roller 2 is immersed in the HF solution in the HF tank. During the rotation of roller 2 with liquid, the bottom of the silicon wafer contacts the HF solution on the roller to remove the mask layer silicon oxide on the back of the silicon wafer; the HF solution level is at 1 / 3 to 2 / 3 of the diameter of roller 2, the mass fraction of the HF solution is 5%-35%, and the temperature of the HF solution is 20-30°C; after passing through the HNO3 tank and the HF tank, the upper and lower surfaces of the silicon wafer are rinsed with deionized water, and then the silicon wafer is dried;

[0057] S11: depositing a silicon nitride layer on the front and back sides of the silicon wafer obtained in S10, wherein the thickness of the silicon nitride film on the front side is 60-90 nm, and the refractive index is 2.0-2.10, and the thickness of the silicon nitride film on the back side is 70-90 nm, and the refractive index is 2.05-2.15;

[0058] S12: printing silver paste on the front and back sides of the silicon wafer obtained in S10;

[0059] Control group

[0060] S1: Put the silicon wafer to be processed into the texturing tank for double-sided texturing to form a pyramid structure;

[0061] S2: Boron diffusion is performed on the front side of the silicon wafer obtained in S1, the boron source is BCl3, and the diffusion square resistance is 100-150ohm / sq;

[0062] S3: Perform SE laser heavy doping on the fine gate line position on the front side of the silicon wafer obtained in S2, and the sheet resistance of the heavily doped area is 70-80 ohm / sq;

[0063] S4: The surface of the silicon wafer obtained in S3 is oxidized to form BSG with a thickness of 80-120nm and a sheet resistance of 250-350ohm / sq;

[0064] S5: Remove BSG and perform alkali polishing on the back of the silicon wafer obtained in S4, and the reflectivity of the back is greater than 40%, and the tower base is greater than 6um; use a chain machine, and under the protection of the front of the silicon wafer, use a HF solution with a volume ratio of 28%-35% and a roller belt liquid to remove BSG on the back and four sides of the silicon wafer; after removing BSG, use a slot machine to perform alkali polishing on the back surface of the silicon wafer, the reaction liquid is an alkali solution and a polishing agent, react at 60-70℃ for 200s, and the BSG on the front is retained; the alkali solution can be KOH or NaOH or an organic base;

[0065] S6: using PECVD to deposit a tunnel oxide layer and doped amorphous silicon on the back of the silicon wafer obtained in S5, the thickness of the ultra-thin oxide layer is 1-1.8nm, the thickness of the doped amorphous silicon layer is 80-130nm, and the thickness of the outer mask layer silicon oxide is 10-50nm;

[0066] S7: performing annealing and crystallization treatment on the silicon wafer obtained in S6, so that the doped amorphous silicon is crystallized into a doped polysilicon film, the doped square resistance is 30-80 ohm / sq, and the annealing temperature is 650-950° C.;

[0067] S8: The silicon wafer obtained in S7 is cleaned by a tank RCA to remove the poly silicon wrapping on the edge and the front, and the front BSG layer is cleaned by an HF acid tank; an alkaline solution and an additive are added to the RCA tank; the poly silicon wrapping is the doped amorphous silicon layer or the outer mask layer silicon oxide formed on the surface of the silicon wafer in S6;

[0068] S9: depositing a layer of AlOx film on the front side of the silicon wafer obtained in S8 by ALD, with a thickness of 3-8 nm;

[0069] S10: depositing a silicon nitride layer on the front and back sides of the silicon wafer obtained in S10, wherein the thickness of the silicon nitride film on the front side is 60-90 nm, and the refractive index is 2.0-2.10, and the thickness of the silicon nitride film on the back side is 70-90 nm, and the refractive index is 2.05-2.15;

[0070] S11: printing silver paste on the front and back sides of the silicon wafer obtained in S10;

[0071] Example 1 mainly adds the step of removing AlOx wrapping, and the control group is a conventional TOPCon battery preparation method; the silicon wafers obtained in the above examples are finally tested for battery appearance, IV and EL performance.

[0072] Table 1 shows the IV test results of silicon wafers obtained after treatment of the control group and Example 1

[0073] category Eta Uoc Isc FF Rs R IRev2 Back AlOx coating 26.358 0.7310 13.9635 85.249 0.000872 394 0.085 No AlOx coating on the back 26.397 0.7311 13.9643 85.363 0.000859 399 0.072

[0074] Compared with the control group, Example 1 of the present invention has improved appearance and reduced contact resistance, which is caused by the removal of AlOx plating on the back of the silicon wafer.

[0075] A TOPCon battery is manufactured based on the above-mentioned preparation method, including a silicon wafer obtained by S12.

[0076] A device, reference Figure 1-8 The method is based on the above-mentioned preparation method and is used for removing AlOx plating on the back of the silicon wafer in S10. The method comprises a cell body 1, in which a plurality of rollers 2 are arranged. The cell body 1 is loaded with a reaction solution, and the liquid level of the reaction solution is set at a position of 1 / 3 to 2 / 3 of the diameter of the roller 2.

[0077] Specifically, Figure 1 The equipment used in S10 includes a spray chamber, a HON3 tank, an HF tank, a rinsing chamber and a drying chamber in sequence along the conveying direction of the silicon wafer; both the HON3 tank and the HF tank can use the structure of the cell body 1, that is, the reaction solution loaded in the cell body 1 can be an HNO3 solution, preferably with a mass fraction of 2%-30% and a temperature of 5-10°C, or an HF solution, preferably with a mass fraction of 5%-35% and a temperature of 20-30°C; along the conveying direction of the silicon wafer, the length of the silicon wafer is greater than the span of three adjacent rollers 2, but less than the span of four adjacent rollers 2; the height of the reaction solution level is set at 1 / 3 to 2 / 3 of the diameter of the roller 2, so that the roller 2 can roll down, the bottom is attached to the solution and then rotates to the upper part, and then the bottom of the silicon wafer, that is, the back of the silicon wafer is in contact with the solution attached to the outer surface of the roller 2 to achieve corrosion removal and plating.

[0078] Compared with the prior art, an apparatus proposed in an embodiment of the present invention combines a roller 2 with a pool body 1 and is loaded with a reaction solution whose liquid level is set at 1 / 3 to 2 / 3 of the diameter of the roller 2, so that when the roller 2 rolls, while conveying the silicon wafer, the roller 2 is attached to the solution at the bottom of the roll, and at the top of the roll, the solution attached to the outer surface contacts the back of the silicon wafer to achieve corrosion removal and wrap-around plating, thereby improving the appearance of the silicon wafer and reducing the contact resistance on the back of the silicon wafer.

[0079] In actual use, the roller 2 is usually made of glass or other materials to prevent corrosion by nitric acid solution. Such materials are prone to slipping when they are stained with the solution and then roll in contact with the silicon wafer, and the silicon wafer may become skewed during transportation.

[0080] In another embodiment of the present invention, the roller 2 can be raised and lowered in the pool body 1, and the side wall of the pool body 1 is provided with an undulating component for driving the roller 2 to reciprocate and rise and fall. Along the conveying direction of the roller 2 to the silicon wafer, among every three adjacent rollers 2, the roller 2 at the end close to the conveying direction of the silicon wafer first rises and then resets, and at the same time, the roller 2 at the end close to the conveying direction of the silicon wafer first drops and then resets. Specifically, no less than three rollers 2 are arranged in the pool body 1; a position sensor is arranged in the pool body 1, and the undulating component is controlled and operated by the position sensor, and the position sensor is arranged near The position sensor near the pool body 1 is used to enter one end of the silicon wafer. When it detects that the silicon wafer has completely entered the pool body 1, it controls the operation of the undulating component to drive the adjacent rollers 2 in groups of three in the conveying direction of the silicon wafer; the grouping of the rollers 2 is based on the conveying direction of the silicon wafer, and is three times and can be repeatedly divided into a group in sequence until the last roller 2 of the last group is the last roller 2 in the conveying direction; for example, when there are five rollers 2, the first, second, and third rollers 2 are a group, and then the second, third, and fourth rollers 2 are a group, and finally the third, fourth, and fifth rollers 2 are a group. The front and rear rollers 2 of the same group rise and fall synchronously and have the same height change, and the middle roller 2 maintains the initial position. In actual use, among the rollers 2 of the same group, after one of the front and rear rollers 2 rises and the other falls, the rollers 2 of this group are inclined downward along the direction of silicon wafer conveying, and the silicon wafer conveyed above the rollers 2 of this group can directly slide down with the rolling of the rollers 2. This sliding mode is controllable compared to slipping, and sliding makes the back of the silicon wafer contact with the reaction solution on the surface of the rollers 2 better and more evenly, and the quality of corrosion and de-plating is good; in addition, when the silicon wafer slides to the roller 2 behind the roller 2 of the group, it can resist the next roller 2 that is not in the group, so that even if the silicon wafer is slipping and tilting, the resistance between the silicon wafer and the surface of the roller 2 can be corrected; further, the reciprocating lifting and lowering of each roller 2 can act on the reaction solution in the pool body 1, so that the reaction solution remains undulating, reducing the sinking of chemical substances caused by standing still, and avoiding the concentration of the upper layer of the solution from dropping below the required value.

[0081] As the preferred technical solution of this embodiment, a lifting bin 3 is provided on the side wall of the pool body 1, and a lifting arm 4 is elastically lifted in the lifting bin 3. One end of the lifting arm 4 is bent around the inner side of the pool body 1 and is sleeved on the rotating shaft of the roller 2. The undulating component is used to drive the lifting arm 4 to rise and fall. Specifically, the lifting arm 4 is in an N shape, bypassing the solid side wall between the pool body 1 and the lifting bin 3, and the two ends extend into the pool body 1 and the lifting bin 3 respectively, and a spacing is left between the inner wall of the upper part and the upper end of the solid side wall bypassed by the lifting arm 4; the lifting arm 4 is arranged on the outer side of one end in the lifting bin 3. A slider 5 is provided, and a slide groove 6 is provided on the side wall of the lifting bin 3 away from the pool body 1. The slider 5 is lifted and lowered in the slide groove 6, and an elastic member 7 is provided in the slide groove 6 to connect one or both ends of the lifting direction of the slider 5. The setting of the elastic member 7 makes the roller 2 stationary in the initial position, that is, the middle position of the lifting range, and when the roller 2 is driven by the undulating component, the elastic member 7 can be deformed and the roller 2 tends to restore the initial position; the lifting arms 4 and the corresponding undulating components are connected to the axial ends of the roller 2, and they run synchronously to keep the roller 2 in a horizontal state.

[0082] As a preferred technical solution of this embodiment, the undulating component includes a first rolling belt 8 and a second rolling belt 9 which are rollingly arranged in the lifting bin 3. The first rolling belt 8 is arranged near the end of the silicon wafer conveying direction, and the second rolling belt 9 is arranged near the end of the silicon wafer conveying direction. An undulating block 10 is arranged on the lifting arm 4, a lifting block 11 is arranged on the first rolling belt 8, and a pressing block 12 is arranged on the second rolling belt 9. The moving stroke of the lifting block 11 passing through the upper side of the first rolling belt 8 and the moving stroke of the pressing block 12 passing through the lower side of the second rolling belt 9 are in the same line and constitute an undulating area. The undulating block 10 is arranged in the undulating area. Specifically, a plurality of rotating wheels for supporting and driving the first rolling belt 8 or the second rolling belt 9 are rotatably arranged in the lifting warehouse 3, and the rotating wheels are driven by a servo system; the first rolling belt 8 is arranged below the axial height of the roller 2, and the second rolling belt 9 is arranged above the axial height of the roller 2; the first rolling belt 8 corresponds to each roller 2 that can rise in the group of all rollers 2, and the second rolling belt 9 corresponds to each roller 2 that can descend in the group of all rollers 2, and the rollers 2 corresponding to the first rolling belt 8 and the second rolling belt 9 may have an overlapping part in the middle; the lifting block 11 and the pressing block 12 are preferably made of rubber or the like, and have a The lifting blocks 11 and the pressing blocks 12 have the same number, preferably 1-2, and when two are preferred, they are arranged equidistantly on the corresponding first rolling belt 8 or second rolling belt 9 with a circumference; in the direction of silicon wafer conveying, the end of the silicon wafer coming is the front and the end of the silicon wafer going is the back, then the lifting blocks 11 and the pressing blocks 12 correspondingly push the front and rear two of every three adjacent undulating blocks 10 in the undulating area, that is, the front and rear two of the rollers 2 grouping in a group of three; the lifting blocks 11 are arranged The moving direction through the upper side of the first rolling belt 8 and the moving direction of the pressing block 12 through the lower side of the second rolling belt 9 are both consistent with the conveying direction of the silicon wafers; a gap is left between one side of the first rolling belt 8 and the second rolling belt 9 and one end of the lifting arm 4 in the lifting bin 3, and the ups and downs block 10 is fixedly set on the inner wall of this end of the lifting arm 4 and maintained in the gap, and the lifting block 11 and the pressing block 12 also extend out of the side of the first rolling belt 8 or the second rolling belt 9 in the direction of the gap, so that when the driving condition of the ups and downs block 10 is met, the lifting and lowering of the ups and downs block 10 is not interfered by the first rolling belt 8 or the second rolling belt 9.

[0083] As a preferred technical solution of this embodiment, a bracket 13 is provided on the pool body 1, and a driving assembly for driving the roller 2 to roll is provided on the bracket 13. The driving assembly includes a transmission wheel 14 rotatably arranged on the bracket 13 and corresponding to the roller 2 one by one. Adjacent transmission wheels 14 are connected by belts 15. One end of the rotating shaft of the roller 2 is connected to a driving rod 16 through a bevel gear transmission. The driving rod 16 vertically penetrates the lifting arm 4, the bracket 13 and the transmission wheel 14, and the driving rod 16 and the transmission wheel 14 are coaxially and synchronously rotated. A motor 17 is fixedly installed on the bracket 13, and the output end of the motor 17 is connected to one of the transmission wheels 14 through a gear transmission. Specifically, a clamping groove is provided on the bracket 13, and each transmission wheel 14 is embedded in the clamping groove so that the lifting and lowering of the transmission wheel 14 relative to the bracket 13 is limited; the bracket 13 is close to the pool body 1 On one side, a transmission bin is arranged above the same end of the rotating shaft of each roller 2, and a transmission bin is arranged on the lifting arm 4 close to the bracket 13. The lower end of the driving rod 16 and the bevel gear transmission structure are arranged in the transmission bin, and the transmission bin protects its internal components from corrosion by the reaction solution; the driving rod 16 maintains the transmission with the rotating shaft of the roller 2, thereby causing the driving rod 16 to rise and fall with the lifting arm 4, and the driving rod 16 slides through the bracket 13, the bent upper part of the lifting arm 4 and the transmission bin, and the driving rod 16 is coaxially connected to the transmission wheel 14 through a sliding key, thereby, the driving rod 16 and the transmission wheel 14 rotate synchronously, and the driving rod 16 can be raised and lowered relative to the transmission wheel 14; the motor 17 drives one of the transmission wheels 14 to rotate through gear transmission, and each transmission wheel 14 rotates synchronously through the belt 15, and then drives each roller 2 to roll synchronously in the same direction through the driving rod 16.

[0084] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a TOPCon battery, characterized in that: The following steps are involved: S1: Put the silicon wafer to be processed into the texturing tank for double-sided texturing to form a pyramid structure; S2: Boron diffusion is performed on the front side of the silicon wafer obtained in S1, the boron source is BCl3, and the diffusion square resistance is 100-150ohm / sq; S3: Perform SE laser heavy doping on the fine gate line position on the front side of the silicon wafer obtained in S2, and the square resistance of the heavily doped area is 70-80ohm / sq; S4: oxidizing the surface of the silicon wafer obtained in S3 to form BSG with a thickness of 80-120 nm and a sheet resistance of 250-350 ohm / sq; S5: The back side of the silicon wafer obtained in S4 is subjected to BSG removal and alkali polishing, and the obtained back side reflectivity is greater than 40%, and the tower base is greater than 6um; S6: using PECVD to deposit a tunneling oxide layer and doped amorphous silicon on the back of the silicon wafer obtained in S5, the thickness of the ultra-thin oxide layer is 1-1.8nm, the thickness of the doped amorphous silicon layer is 80-130nm, and the thickness of the outer mask layer silicon oxide is 100-150nm; S7: performing annealing and crystallization treatment on the silicon wafer obtained in S6, so that the doped amorphous silicon is crystallized into a doped polysilicon film, the doped square resistance is 30-80 ohm / sq, and the annealing temperature is 650-950° C.; S8: The silicon wafer obtained in S7 is cleaned by a tank RCA to remove the poly silicon plating on the edge and the front, and the front BSG layer is cleaned by an HF acid tank to retain a certain thickness of silicon oxide on the back mask layer; S9: depositing a layer of AlOx film on the front side of the silicon wafer obtained in S8 by ALD, with a thickness of 3-8 nm; S10: removing AlOx coating from the back of the silicon wafer obtained in S9; A chain machine is used, and the front side of the silicon wafer is protected by a water film, and a 2%-30% HNO3 solution is used to selectively etch the AlOx film layer coated on the back side of the silicon wafer, and then a 5%-35% HF solution is used to remove the mask layer silicon oxide on the back side of the silicon wafer; the silicon wafer is transported by a roller (2), and water is dripped onto the front side of the silicon wafer by a spray device to form a water film; the amount of water on the upper surface of the silicon wafer is 5-8 mg; the silicon wafer is transported by the roller (2) to the HNO3 tank, and the bottom of the roller (2) is immersed in the HNO3 solution in the HNO3 tank. During the roller (2) rotating with the liquid, the bottom of the silicon wafer and the HNO on the roller (2) are in contact with each other. 3 solution to remove AlOx plated on the back of the silicon wafer; the HNO3 solution level is at a position of 1 / 3 to 2 / 3 of the diameter of the roller (2), and the temperature of the HNO3 solution is 5-10°C; the silicon wafer is transported by the roller (2), passes through the HNO3 tank, and then continues to be transported to the HF tank, the bottom of the roller (2) is immersed in the HF solution in the HF tank, and during the roller (2) rotating with the liquid, the bottom of the silicon wafer contacts the HF solution on the roller to remove the mask layer silicon oxide on the back of the silicon wafer; the HF solution level is at a position of 1 / 3 to 2 / 3 of the diameter of the roller (2), and the temperature of the HF solution is 20-30°C; S11: depositing a silicon nitride layer on the front and back sides of the silicon wafer obtained in S10, wherein the thickness of the silicon nitride film on the front side is 60-90 nm, and the refractive index is 2.0-2.10, and the thickness of the silicon nitride film on the back side is 70-90 nm, and the refractive index is 2.05-2.15; S12: Printing silver paste on the front and back sides of the silicon wafer obtained in S10.

2. The method for preparing a TOPCon battery according to claim 1, characterized in that: In S5, a chain machine is used, and the front side of the silicon wafer is protected by a water film, and the BSG on the back and four sides of the silicon wafer is removed by using a 28%-35% HF solution and a roller belt liquid; After removing BSG, use a tank machine to perform alkaline polishing on the back surface of the silicon wafer. The reaction liquid is an alkaline solution and a polishing agent. The reaction is carried out at 60-70°C for 200s, and the BSG on the front side is retained.

3. The method for preparing a TOPCon battery according to claim 1, characterized in that: The silicon wafer in S10 is conveyed by rollers, passes through a HNO3 tank and an HF tank, and then the upper and lower surfaces of the silicon wafer are rinsed with deionized water, and then the silicon wafer is dried.

4. A TOPCon battery, which is manufactured based on the preparation method according to any one of claims 1 to 3, characterized in that: Including the silicon wafer obtained by S12.

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