Back contact battery laser grooving method and device with low laser damage

Abstract

The invention discloses a back contact cell laser grooving method and device with low laser damage. The method comprises the following steps: S1, preparing a solar cell precursor; s2, PECVD (plasma enhanced chemical vapor deposition); s3, high-temperature annealing; s4, laser film opening; s5, removing the mask layer; and S6, carrying out RCA cleaning. According to the invention, an extra intrinsic polycrystalline silicon / second mask layer laminated protection layer is arranged, and a laser film opening technology and an improved RCA cleaning technology are combined to replace an original tunneling oxide layer / heavily doped polycrystalline silicon layer passivation contact structure to complete a laser grooving task; in the laser grooving process, the additionally-arranged intrinsic polycrystalline silicon / second mask layer stack bears all laser effects and absorbs all laser damage, the effect of protecting an inner layer passivation structure is achieved, and the situation that high-energy laser causes laser damage to an inner layer tunneling oxide layer / heavily-doped polycrystalline silicon layer passivation contact structure is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of solar cells, and in particular to a laser grooving method and equipment for a back contact cell with low laser damage. Background Art

[0002] Laser grooving is a crucial technology in the manufacture of back-contact batteries. This technology combines laser film opening and silicon wafer cleaning processes to achieve isolation between the N-type and P-type regions of the battery, and is the key to forming the finger-type alternating structure of the positive and negative electrodes on the back of the back-contact battery. Laser grooving is achieved by irradiating the battery surface with a high-energy-density laser beam. The battery surface absorbs the laser energy and the temperature rises, producing a drastic volume effect, thereby destroying the structure of the surface mask layer and completing the laser film opening. After laser film opening, the laser film opening area is selectively etched through the silicon wafer cleaning process to achieve the purpose of isolating the N-type and P-type regions on the back.

[0003] However, commonly used mask layers (such as SiO x 、SiN x The bandgap of Poly-Si and Si substrate is relatively low. Therefore, the mask layer absorbs less laser energy, while the energy absorbed by Poly-Si and Si substrate is very large. Poly-Si will be destroyed by a drastic volume effect when absorbing high laser energy. The surface mask layer will be destroyed under the drastic volume expansion of Poly-Si, thus forming an open film of the mask layer. Therefore, during the laser grooving process, the high energy of the laser will cause the redistribution of the doping concentration of Poly-Si, and will also destroy the structure of crystalline silicon, leaving laser damage and affecting the passivation performance of the battery. Therefore, a laser grooving method and equipment for back-contact batteries with low laser damage is urgently needed to solve the above problems. Summary of the invention

[0004] The object of the present invention is to provide a method and device for laser grooving a back contact battery with low laser damage, so as to solve the above-mentioned deficiencies in the prior art.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A laser grooving method for a back contact battery with low laser damage comprises the following steps:

[0007] S1: preparing a solar cell precursor, wherein the solar cell precursor comprises a silicon substrate, a first surface and a second surface;

[0008] S2: depositing a tunnel oxide layer, in-situ doped amorphous silicon, a first mask layer, an intrinsic amorphous silicon and a second mask layer on the first surface in sequence by PECVD thin film deposition; and correspondingly forming each film layer on the second surface in sequence by wrapping plating;

[0009] S3: Anneal in a high-temperature furnace tube, in which the in-situ doped amorphous silicon is transformed into heavily doped polycrystalline silicon, and the intrinsic amorphous silicon is transformed into intrinsic polycrystalline silicon, thereby forming a laser-treated structure on the first surface;

[0010] S4: Selectively open the second mask layer on the laser-treated structure through a high-energy density laser beam to form a laser opening area;

[0011] S5: Remove the second mask layer on the second surface through chain HF cleaning;

[0012] S6: Remove the polysilicon overplating on the second surface and the intrinsic polysilicon / second mask layer stack protection layer on the first surface through RCA cleaning, and form a laser grooving structure on the first surface;

[0013] S7: On the basis of the solar cell semi-finished product obtained in S6, complete the processes of depositing the passivation film layer and printing the metal electrodes to form a finished solar cell.

[0014] Preferably, in S1, the silicon substrate is an N-type silicon wafer or a P-type silicon wafer; the first surface is an alkali-polished surface; the second surface is an alkali-polished surface or a textured surface.

[0015] Preferably, in S2, the solar cell precursor is placed in a high-temperature furnace tube and PECVD thin film deposition is carried out under glow discharge conditions, including the following steps:

[0016] S2.1: Introduce N2O into the high-temperature furnace tube to deposit a tunneling oxide layer;

[0017] S2.2: Introduce SiH4, PH3 and H2 into the high-temperature furnace tube to deposit in-situ doped amorphous silicon;

[0018] S2.3: Introduce SiH4 and N2O into the high-temperature furnace tube to deposit the first mask layer;

[0019] S2.4: Introduce SiH4 into the high-temperature furnace tube to deposit intrinsic amorphous silicon;

[0020] S2.5: Introduce SiH4 and N2O into the high-temperature furnace tube to deposit the second mask layer.

[0021] Preferably, in S3, the laser-treated structure is a stacked structure of a tunneling oxide layer, heavily doped polycrystalline silicon, a first mask layer, intrinsic polycrystalline silicon, and a second mask layer stacked in sequence from inside to outside on the first surface; among them, the thickness of the tunneling oxide layer is 1.2 - 2.0 nm, the thickness of the heavily doped polycrystalline silicon is 50 - 300 nm, the thickness of the first mask layer is 1 - 30 nm, the thickness of the intrinsic polycrystalline silicon layer is 1 - 200 nm, and the thickness of the second mask layer is 1 - 30 nm.

[0022] Preferably, S6 includes the following steps:

[0023] S6.1: First caustic wash: Use KOH chemical solution to etch and remove the polysilicon overplating on the second surface, as well as the second mask layer and the intrinsic polysilicon in the laser opening area on the first surface;

[0024] S6.2: First pickling: Use HF chemical solution to corrode and remove the first mask layer on the second surface, as well as the first mask layer in the laser opening area on the first surface;

[0025] S6.3: Second caustic wash: Use KOH chemical solution to etch and remove the heavily doped polysilicon overplating on the second surface, the intrinsic polysilicon on the non-laser opening area of the first surface, and the heavily doped polysilicon on the laser opening area of the first surface; and partially etch the silicon substrate in the laser opening area to form a selective slot for the silicon substrate;

[0026] S6.4: Second pickling: Use HF chemical solution to corrode and remove the first mask layer on the non-laser opening area of the first surface to complete the laser slotting.

[0027] A device is used in S6 of the above-mentioned laser slotting method for a back contact battery with low laser damage, including a cabinet body. An acid pickling tank and a caustic washing tank are arranged in the cabinet body. A water washing tank is arranged between the acid pickling tank and the caustic washing tank. It also includes a transportation component arranged in the cabinet body. A flower basket component for loading battery wafers is arranged at the lower end thereof. The flower basket component includes a bracket connected to the transportation component and a flower basket frame rotatably connected to the lower end of the bracket. A docking block is arranged at the rotating shaft end of the flower basket frame. A docking component for connecting the docking block is rotatably arranged in the water washing tank. A servo motor for controlling the rotation of the docking component is arranged in the cabinet body;

[0028] Preferably, the transportation component includes a cross beam arranged to be lifted and lowered in the cabinet body. A sliding seat is movably arranged on the cross beam. A sliding groove is arranged at the lower end of the sliding seat. A sliding plate is arranged at the upper end of the bracket. The sliding plate is slid into the sliding groove with damping.

[0029] Preferably, the docking component includes a docking seat rotatably arranged on the inner wall of the water washing tank. A rotating rod coaxially and fixedly connected to the docking seat is synchronously rotated at the output end of the servo motor. A holding component for limiting the docking block is arranged on the bracket. The docking seat can be axially moved and is linked with the descent of the sliding seat through a first linkage component. When the sliding seat descends to the lowest position, the docking block and the docking seat are horizontally corresponding, and the first linkage component links the docking seat to axially move close to the docking block to form connection and transmit rotation, and the holding component cancels the limit on the docking block.

[0030] Preferably, the first linkage assembly includes a forklift rack that is vertically movable inside the cabinet. A sliding groove is provided on the forklift rack. A synchronous sleeve is sleeved on the rotating rod. A sliding pin that is movably connected to the sliding groove is provided on the side wall of the synchronous sleeve. The upper end of the forklift rack is connected to a pressing plate. The pressing plate is elastically vertically arranged inside the cabinet and is in the descending stroke of the sliding seat.

[0031] Preferably, the holding assembly includes a guide sleeve provided on the outer side of the lower end of the bracket. A guide block sleeved on the rotating shaft end of the flower basket rack is elastically telescopically connected to the guide sleeve. A limiting sleeve is fixedly provided on the guide block.

[0032] In the above technical solution, the beneficial effect of the present invention is:

[0033] By providing an additional intrinsic polysilicon and a second mask layer, combining the laser film opening technology and the RCA cleaning process, this laser grooving method for back contact batteries with low laser damage replaces the original tunneling oxide layer / heavily doped polysilicon layer passivation contact structure to complete the laser grooving task. During the laser action process, the additionally provided intrinsic polysilicon / second mask layer stack bears all the laser actions and absorbs all the laser damage, acting as an outer protective layer to avoid laser damage to the inner tunneling oxide layer / heavily doped polysilicon layer passivation contact structure caused by high-energy lasers. Moreover, the intrinsic polysilicon / second mask layer stack structure with high damage is completely removed during the RCA cleaning process, avoiding leaving a laser-damaged structure on the battery. The excellent passivation performance of the battery is retained, thereby improving the conversion efficiency of the battery.

[0034] It should be understood that the foregoing general description and the following detailed description are merely exemplary and explanatory and are not intended to limit the present disclosure.

[0035] This application document provides an overview of various implementations or examples of the technology described in the present disclosure and does not represent a full disclosure of the entire scope of the disclosed technology or all features. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0037] Figure 1 It is a schematic diagram of steps S1 - S6 provided by an embodiment of the present invention;

[0038] Figure 2 It is a schematic diagram of the specific steps of step S6 provided by an embodiment of the present invention;

[0039] Figure 3 Schematic diagram of the overall structure of the device provided by an embodiment of the present invention;

[0040] Figure 4 Provided by an embodiment of the present invention Figure 3 Enlarged schematic diagram of the structure at A in

[0041] Figure 5 Schematic diagram of the side view sectional structure of the overall device provided by an embodiment of the present invention;

[0042] Figure 6 Provided by an embodiment of the present invention Figure 5 Enlarged schematic diagram of the structure at B in

[0043] Figure 7 Provided by an embodiment of the present invention Figure 5 Enlarged schematic diagram of the structure at C in

[0044] Figure 8 Schematic diagram of the docking seat and the first linkage assembly provided by an embodiment of the present invention;

[0045] Figure 9 Schematic diagram of the docking seat and the second linkage assembly provided by an embodiment of the present invention.

[0046] Explanation of reference numerals:

[0047] 1. Silicon substrate; 101. First surface; 102. Second surface; 2. Tunneling oxide layer; 3. In-situ doped amorphous silicon; 31. Heavily doped polycrystalline silicon; 4. First mask layer; 5. Intrinsic amorphous silicon; 51. Intrinsic polycrystalline silicon; 6. Second mask layer; 7. Laser opening area; 8. Cabinet; 9. Pickling tank; 10. Alkaline cleaning tank; 11. Water washing tank; 12. Bracket; 13. Basket rack; 14. Docking block; 15. Servo motor; 16. Cross beam; 17. Slide seat; 18. Slide-in groove; 19. Slide-in plate; 20. Docking seat; 21. Rotating rod; 22. Fork frame; 23. Sliding groove; 24. Synchronous sleeve; 25. Sliding pin; 26. Pressure plate; 27. Guide sleeve; 28. Guide block; 29. Limit sleeve; 30. Vibration wheel; 32. Rotating tooth. Detailed implementation manners

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0049] Please refer to Figure 1-2, a laser grooving method for back contact cells with low laser damage provided by an embodiment of the present invention includes the following steps:

[0050] S1: Prepare a solar cell precursor, which includes a silicon substrate 1, a first surface 101 and a second surface 102; the silicon substrate 1 is an N-type silicon wafer; the silicon substrate 1 is polished on both sides by KOH chemical solution to form the first surface 101 and the second surface 102, and both the first surface 101 and the second surface 102 are polished surfaces;

[0051] S2: Through PECVD film deposition, sequentially deposit a tunneling oxide layer 2, an in-situ doped amorphous silicon 3, a first mask layer 4, an intrinsic amorphous silicon 5 and a second mask layer 6 on the first surface 101; corresponding film layers are formed by overcoating on the second surface 102 in turn; the in-situ doped amorphous silicon 3 is in-situ phosphorus-doped amorphous silicon; both the first mask layer 4 and the second mask layer 6 are silicon oxide;

[0052] In S2, the solar cell precursor is placed in a high-temperature furnace tube and PECVD film deposition is carried out under glow discharge conditions, including the following steps:

[0053] S2.1: Introduce N2O into the high-temperature furnace tube to deposit the tunneling oxide layer 2, at a temperature of 400 - 600 °C and a pressure of 50 - 200 Torr;

[0054] S2.2: Introduce SiH4, PH3 and H2 into the high-temperature furnace tube to deposit the in-situ doped amorphous silicon 3, at a temperature of 400 - 600 °C and a pressure of 100 - 300 Torr;

[0055] S2.3: Introduce SiH4 and N2O into the high-temperature furnace tube to deposit the first mask layer 4, at a temperature of 400 - 600 °C and a pressure of 50 - 200 Torr;

[0056] S2.4: Introduce SiH4 into the high-temperature furnace tube to deposit the intrinsic amorphous silicon 5, at a temperature of 400 - 600 °C and a pressure of 100 - 300 Torr;

[0057] S2.5: Introduce SiH4 and N2O into the high-temperature furnace tube to deposit the second mask layer 6, at a temperature of 400 - 600 °C and a pressure of 50 - 200 Torr;

[0058] S3: Anneal in a high-temperature furnace tube at a temperature of 800 - 1000 °C for 10 - 60 min. In-situ doping causes amorphous silicon 3 to transform into heavily doped polycrystalline silicon 31, and intrinsic amorphous silicon 5 to transform into intrinsic polycrystalline silicon 51, thereby forming a laser-treated structure on the first surface 101. The disordered amorphous silicon structure rearranges to form an ordered polycrystalline silicon, and during this process, the doping atoms are activated. The doping atoms are phosphorus atoms. In S3, the laser-treated structure is a stacked structure on the first surface 101, which consists of a tunneling oxide layer 2, heavily doped polycrystalline silicon 31, a first mask layer 4, intrinsic polycrystalline silicon 51, and a second mask layer 6 stacked in sequence from the inside to the outside. Among them, the stack of the tunneling oxide layer 2 and the heavily doped polycrystalline silicon 31 serves as a tunneling oxide passivation contact structure; the stack of the intrinsic polycrystalline silicon 51 and the second mask layer 6 serves as a protective layer; the first mask layer 4 serves as an isolation layer between the stack of the tunneling oxide layer 2 / heavily doped polycrystalline silicon 31 and the stack of the intrinsic polycrystalline silicon 51 / second mask layer 6. Among them, the thickness of the tunneling oxide layer 2 is 1.2 - 2.0 nm, the thickness of the heavily doped polycrystalline silicon 31 is 50 - 300 nm, the thickness of the first mask layer 4 is 1 - 30 nm, the thickness of the intrinsic polycrystalline silicon layer 51 is 1 - 200 nm, and the thickness of the second mask layer 6 is 1 - 30 nm;

[0059] S4: Selectively open the second mask layer 6 on the laser-treated structure through a high-energy density laser beam to form a laser opening area 7. Use a green picosecond laser, with a laser power of 1 - 50 W and a laser frequency of 1 - 2000 KHz. The high-energy density laser beam irradiates the laser-treated structure according to a pattern for laser opening;

[0060] S5: Remove the second mask layer 6 on the second surface 102 through chain HF cleaning, with an HF volume concentration of 1% - 40%, to achieve single-sided removal of the mask layer;

[0061] S6: Remove the overplating of the heavily doped polycrystalline silicon 31 on the second surface 102 and the protective layer of the stack of the intrinsic polycrystalline silicon 51 / second mask layer 6 on the first surface 101 through RCA cleaning, and form a laser grooving structure on the first surface 101;

[0062] S6 includes the following steps:

[0063] S6.1: First alkali wash: Use a KOH chemical solution with a KOH volume concentration of 1% - 20%, a temperature of 50 - 90 °C, and 1 - 15 L of an overplating removal additive to etch and remove the overplating of the intrinsic polycrystalline silicon 51 on the second surface 102, as well as the second mask layer 6 and the intrinsic polycrystalline silicon 51 in the laser opening area on the first surface 101;

[0064] S6.2: First pickling: Using an HF chemical solution with an HF volume concentration of 1% - 30%, etch away the first mask layer 4 on the second surface 102 and the first mask layer 4 in the laser opening area of the first surface 101;

[0065] S6.3: Second alkali wash: Using a KOH chemical solution with a KOH volume concentration of 1% - 20%, a temperature of 50 - 90 °C, and 1 - 15 L of de-wrapping plating additive, etch away the heavy-doped polysilicon 31 wrap plating on the second surface 102, the intrinsic polysilicon 51 in the non-laser opening area of the first surface 101, and the heavy-doped polysilicon 31 in the laser opening area of the first surface 101; and partially etch the silicon substrate 1 in the laser opening area to form a selective slotting of the silicon substrate 1;

[0066] S6.4: Second pickling: Using an HF chemical solution with an HF volume concentration of 1% - 30%, etch away the first mask layer 4 in the non-laser opening area of the first surface 101 to complete the laser slotting.

[0067] S7 Post-treatment of solar cell: On the basis of the above semi-finished solar cell, complete processes such as passivation film coating and metal electrode printing to form a finished solar cell.

[0068] The beneficial effects of the present invention are: By setting an additional intrinsic polysilicon 51 and a second mask layer 6, combining laser opening technology and RCA cleaning process, replace the original tunneling oxide layer 2 / heavy-doped polysilicon 31 passivation contact structure to complete the laser slotting task; during the laser action process, the additional intrinsic polysilicon 5 / second mask layer 6 stack bears all the laser actions and absorbs all the laser damages, playing the role of an outer protective layer, avoiding laser damage to the inner tunneling oxide layer 2 / heavy-doped polysilicon 31 layer passivation contact structure caused by high-energy laser. And, the intrinsic polysilicon 51 / second mask layer 6 stack structure with high damage is completely removed during the RCA cleaning process, avoiding leaving a laser-damaged structure on the battery; retaining the excellent passivation performance of the battery, thereby improving the conversion efficiency of the battery.

[0069] Please refer to Figures 3-9, an apparatus provided by an embodiment of the present invention is also used in S6 of the above-mentioned laser grooving method for back-contact battery with low laser damage, and includes a cabinet body 8. An acid pickling tank 9 and an alkali washing tank 10 are arranged in the cabinet body 8. A water washing tank 11 is arranged between the acid pickling tank 9 and the alkali washing tank 10. It further includes a transportation component which is arranged in the cabinet body 8, and a flower basket component for loading battery wafers is arranged at its lower end. The flower basket component includes a bracket 12 connected to the transportation component and a flower basket frame 13 rotatably connected to the lower end of the bracket 12. A docking block 14 is arranged at the rotating shaft end of the flower basket frame 13. A docking component for connecting the docking block 14 is rotatably arranged in the water washing tank 11. A servo motor 15 for controlling the rotation of the docking component is arranged in the cabinet body 8. Specifically, the cabinet body 8 is preferably a fume hood to ensure safe use. A window area is arranged on the cabinet body 8. The bottom surface of the window area is recessed in sequence with the acid pickling tank 9, the water washing tank 11 and the alkali washing tank 10, and the transportation component is arranged in the window area. Nozzles are arranged in the acid pickling tank 9, the alkali washing tank 10 and the water washing tank 11, and a liquid discharge port with an automatic control switch is arranged at the bottom. HF chemical liquid is sprayed into the acid pickling tank 9, and the volume concentration of HF is 1%-30%. KOH chemical liquid is sprayed into the alkali washing tank 10, the volume concentration of KOH is 1%-20%, the temperature is 50-90°C, and the de-brazing additive is 1-15L. The transportation component is used to drive the flower basket component to move horizontally and vertically, so as to switch the flower basket component to enter and exit the acid pickling tank 9, the alkali washing tank 10 and the water washing tank 11; the transportation component is controlled by a servo system to operate. The flower basket component is made of corrosion-resistant material; the bracket 12 is vertically arranged, the bracket 12 is in a "C" shape with the opening facing downwards and is connected to the flower basket frame 13; the flower basket frame 13 is in a cylindrical frame structure, and its axis is perpendicular to the bracket 12; three or four ribs are evenly arranged on the circumferential side of the flower basket frame 13, and grooves with equal spacing are arranged inside the ribs for positioning the battery wafers. One of the ribs is detachably arranged, so as to facilitate the loading and unloading of the battery wafers. Specifically, it is prior art and will not be elaborated. The rotating shaft end of the flower basket frame 13 penetrates through the bracket 12, and the docking block 14 is in a rectangular block shape; the docking component is used to horizontally correspond to and form a connection with the docking block 14 after the flower basket component is accurately aligned with the water washing tank 11 and descends into it. At this time, the rotation axis of the flower basket frame 13 is collinear with the rotation axis of the docking component. In actual use of this technical solution, the transportation component drives the flower basket component to be accurately aligned with the water washing tank 11 and makes the flower basket component descend into the water washing tank 11. When the flower basket component carrying the battery wafers descends to the lowest position in the water washing tank 11, the docking block 14 forms a connection with the docking component. Then, the servo motor 15 drives the docking component to rotate, and the docking component can drive the flower basket frame 13 to rotate through the docking block 14. At this time, the nozzles in the water washing tank 11 first spray water to wash the battery wafers on the flower basket frame 13. After the set washing time, the nozzles stop spraying water, and the flower basket frame 13 continues to rotate, thereby promoting the automatic drying of the battery wafers.

[0070] As a preferred technical solution of this embodiment, the transportation component includes a cross beam 16 that is lifted and arranged inside the cabinet body 8. A sliding seat 17 is movably arranged on the cross beam 16. A sliding groove 18 is arranged at the lower end of the sliding seat 17. A sliding plate 19 is arranged at the upper end of the bracket 12. The sliding plate 19 is slid into the sliding groove 18 with damping. Specifically, the lifting of the cross beam 16 and the movement of the sliding seat 17 on the cross beam 16 are both controlled by a servo system. The movement of the flower basket assembly driven by the cooperation of the lifting of the cross beam 16 and the movement of the sliding seat 17 is as follows: The flower basket assembly is initially positioned directly above the water washing pool 11. Then the flower basket assembly is first translated to directly above the pickling pool 9. The flower basket assembly descends into the pickling pool 9 and is fixed in position for a period of time to complete one pickling. The flower basket assembly ascends, then is translated to directly above the water washing pool 11, and then descends into the water washing pool 11 and is fixed in position for a period of time to complete one water washing. The flower basket assembly ascends, then is translated to directly above the alkali washing pool 10, and then descends into the alkali washing pool 10 and is fixed in position for a period of time to complete one alkali washing. The flower basket assembly ascends, then moves to directly above the water washing pool 11, and then descends into the water washing pool 11 and is fixed in position for a period of time to complete another water washing. The flower basket assembly ascends, that is, one movement route is completed. In actual use, according to the steps of S6, the flower basket assembly needs to perform the above movement route twice to complete the processing steps of S6. The lower end of the sliding seat 17 is arranged in a cover shape and can separately cover the pickling pool 9, the alkali washing pool 10 or the water washing pool 11. The sliding groove 18 is horizontally arranged, and the extending direction corresponds to the direction of entering and exiting the cabinet body 8. The inner wall of the sliding groove 18 is rough. The sliding plate 19 slides into the sliding groove 18 with damping, that is, when the sliding plate 19 is not affected by external force, it automatically stays stationary in the sliding groove 18.

[0071] As a preferred technical solution of this embodiment, the docking component includes a docking seat 20 rotatably arranged on the inner wall of the water washing pool 11. A rotating rod 21 coaxially and fixedly connected to the docking seat 20 is synchronously rotatably arranged at the output end of the servo motor 15. A holding component for limiting the docking block 14 is arranged on the bracket 12. The docking seat 20 is axially movable and is linked with the downward movement of the sliding seat 17 through a first linkage component. When the sliding seat 17 descends to the lowest position, the docking block 14 is horizontally corresponding to the docking seat 20, and the first linkage component links the docking seat 20 to axially move closer to the docking block 14 to form a connection for transmitting rotation, and the holding component cancels the limit on the docking block 14. Specifically, the docking seat 20 is in the shape of a circular plate, with a groove matching the docking block 14 opened at the center, and the axis is parallel to the rotation axis of the flower basket rack 13; the servo motor 15 is installed inside the corresponding cabinet body 8 on the side wall of the water washing pool 11. One end of the rotating rod 21 is coaxially and fixedly connected to the docking seat 20, and the other end is provided with a torsion groove. The output end of the servo motor 15 is coaxially inserted into the torsion groove to achieve synchronous rotation without affecting the axial movement of the rotating rod 21; the holding component is used to limit and hold the docking block 14 in the vertical state; under the control of the servo motor 15, before and after the rotation of the docking seat 20, the groove on it is correspondingly stopped in the vertical state; the axial movement of the docking seat 20 facilitates the connection with the docking block 14 and cancels the limit of the holding component on the docking block 14 in a pushing manner.

[0072] As a preferred technical solution of this embodiment, the first linkage assembly includes a fork 22 that is vertically movably arranged in the cabinet 8. A sliding groove 23 is arranged on the fork 22. A synchronous sleeve 24 is sleeved on the rotating rod 21. A sliding pin 25 that is movably connected to the sliding groove 23 is arranged on the side wall of the synchronous sleeve 24. The upper end of the fork 22 is connected to a pressing plate 26. The pressing plate 26 is elastically vertically arranged in the cabinet 8 and is in the descending stroke of the sliding seat 17. Specifically, an activity cavity for the fork 22 to move is formed in the cabinet 8; the fork 22 is U-shaped, with the opening facing downward and clamped on the rotating rod 21; the sliding groove 23 is inclined, and the upper end is arranged closer to the direction of the water washing pool 11 than the lower end; two spaced convex rings are arranged on the rotating rod 21, and the synchronous sleeve 24 is limited between the two convex rings, so that the synchronous sleeve 24 moves axially synchronously with the rotating rod 21 without affecting the rotation of the rotating rod 21; the inner bottom surface of the window area of the cabinet 8 is provided with a retraction groove that matches the pressing plate 26, and a spring is arranged in the retraction groove to abut against the lower end of the pressing plate 26, thereby maintaining the position where the pressing plate 26 extends upward out of the retraction groove. Corresponding to the fork 22 being at the highest position of the lifting formation, the sliding pin 25 corresponds to the lower end of the sliding groove 23, that is, the rotating rod 21 drives the docking seat 20 to approach the inner wall of the water washing pool 11; in actual use, when the sliding seat 17 drives the flower basket assembly to be directly opposite to the water washing pool 11 and starts to descend, the docking block 14 is limited in the vertical position by the holding assembly. As the flower basket assembly descends, the height of the docking block 14 approaches the docking seat 20. When the sliding seat 17 descends to be close to covering the water washing pool 11, the sliding seat 17 starts to press down the pressing plate 26. Then, the pressing plate 26 resists the elastic force and descends. The pressing plate 26 drives the fork 22 to descend. The fork 22 drives the synchronous sleeve 24 to move in the direction close to the water washing pool 11 through the sliding groove 23 and the sliding groove 23, that is, the synchronous sleeve 24 drives the rotating rod 21 and the docking seat 20 to approach the docking block 14, so that the docking block 14 and the docking seat 20 are connected, and the docking seat 20 cancels the limit on the docking block 14 by the pushing method. The flower basket rack 13 can be driven to rotate by the servo motor 15 under the connection of the docking block 14 and the docking seat 20; when the servo motor 15 stops rotating, the docking block 14 returns to the vertical position, and the sliding seat 17 rises, then the pressing plate 26 elastically returns, driving the fork 22 to rise, and further driving the docking seat 20 to move away from the docking block 14 to return to the initial position.

[0073] As a preferred technical solution of this embodiment, the holding assembly includes a guide sleeve 27 disposed on the outer side of the lower end of the bracket 12. An elastic telescopic connection is provided on the guide sleeve 27 with a guide block 28 sleeved on the rotating shaft end of the flower basket rack 13. A limiting sleeve 29 is fixedly arranged on the guide block 28. Specifically, the guide sleeve 27 is preferably polygonal, and the guide block 28 telescopically moves along the guide of the guide sleeve 27 without rotating; another spring is arranged in the guide sleeve 27 to connect the guide block 28, so that the guide block 28 is in a state of protruding from the guide sleeve 27 without external force; a clamping groove matching the docking block 14 is arranged on the limiting sleeve 29. In the vertical state of the docking block 14, the limiting sleeve 29 is sleeved on the docking block 14 with the clamping groove driven by the elastic protrusion of the guide block 28, so as to keep the docking block 14 in the vertical position; when the docking block 14 corresponds to the docking seat 20 and the slide seat 17 descends to the lowest position to trigger the pressing plate 26 to descend, the axial movement of the docking seat 20 close to the docking block 14 can connect the docking seat 20 and the docking block 14. At the same time, the docking seat 20 pushes the limiting sleeve 29, so that the guide block 28 contracts into the guide sleeve 27, and the limiting sleeve 29 leaves the docking block 14, that is, the restriction on the rotation of the docking block 14 is cancelled, and the docking block 14 can rotate with the docking seat 20.

[0074] In another embodiment proposed by the present invention, the flower basket rack 13 is axially movable on the bracket 12, and a vibration assembly for driving the flower basket rack 13 to reciprocate axially is arranged in the pickling tank 9; the vibration assembly includes a vibration wheel 30 rotatably arranged in the pickling tank 9. A plurality of circumferentially distributed rotating teeth 32 are arranged on the end face of the vibration wheel 30 facing the inner side of the pickling tank 9. The vibration wheel 30 is axially movable and is linked with the descent of the slide seat 17 through a second linkage assembly. The structure and principle of the second linkage assembly are the same as those of the first linkage assembly, and it is only used to trigger the axial movement of the vibration wheel 30. Specifically, the movement principle of the vibration wheel 30 is the same as that of the docking seat 20, that is, after the flower basket rack 13 descends to the corresponding position in the pickling tank 9, the vibration wheel 30 approaches the docking block 14 and can rotate. When the vibration wheel 30 approaches the docking block 14, the docking block 14 is in the rotation range of the rotating teeth 32. The rotating teeth 32 are in a slope shape or a wave shape. When the vibration wheel 30 rotates, the rotating teeth 32 cyclically squeeze and push the docking block 14, thereby causing the flower basket rack 13 to move axially. And because the docking block 14 is attached to the limiting sleeve 29 and the limiting sleeve 29 is elastically telescoped by the guide block 28, after the flower basket rack 13 is axially moved by the push each time, it can recover its position by means of the elastic force, so that the flower basket rack 13 moves axially back and forth to form vibration, so as to better pickle the battery slices.

[0075] As a preferred technical solution of this embodiment, the same vibration assembly as that in the pickling tank 9 is arranged in the alkali washing tank 10. Specifically, vibration cleaning can also be realized in the alkali washing tank 10, and the internal principle is the same as that of the pickling tank 9.

[0076] Only some exemplary embodiments of the present invention have been described above by way of illustration. Without doubt, for those of ordinary skill in the art, various different ways can be used to modify the described embodiments without departing from the spirit and scope of the present invention. Therefore, the above drawings and description 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 laser grooving method for back contact cells with low laser damage, characterized in that: The following steps are involved: S1: preparing a solar cell precursor, wherein the solar cell precursor comprises a silicon substrate (1), a first surface (101) and a second surface (102); S2: depositing a tunnel oxide layer (2), in-situ doped amorphous silicon (3), a first mask layer (4), intrinsic amorphous silicon (5) and a second mask layer (6) on the first surface (101) in sequence by PECVD thin film deposition; and correspondingly forming each film layer on the second surface (102) in sequence by wrapping plating; S3: performing annealing in a high-temperature furnace tube, converting the in-situ doped amorphous silicon (3) into heavily doped polycrystalline silicon (31), and converting the intrinsic amorphous silicon (5) into intrinsic polycrystalline silicon (51), thereby forming a laser-processed structure on the first surface (101); S4: selectively opening the second mask layer (6) on the first surface (101) by a high energy density laser beam to form a laser opening area (7); S5: removing the second mask layer (6) on the second surface (102) by chain HF cleaning; S6: removing the polysilicon wrap-around coating on the second surface (102) and the intrinsic polysilicon (51) / second mask layer (6) stacked protective layer on the first surface (101) through RCA cleaning, and forming a laser groove structure on the first surface (101); S7: Based on the semi-finished solar cell product obtained in S6, the passivation film coating and metal electrode printing processes are completed to form a finished solar cell product.

2. The laser grooving method for back contact cells with low laser damage according to claim 1, characterized in that: The silicon substrate (1) in S1 is an N-type silicon wafer or a P-type silicon wafer; the first surface (101) is an alkali polished surface; and the second surface (102) is an alkali polished surface or a velvet surface.

3. The laser grooving method for back contact battery with low laser damage according to claim 1, characterized in that: In S2, the solar cell precursor is placed in a high temperature furnace tube and PECVD thin film deposition is performed under glow power generation conditions, including the following steps: S2.1: introducing N2O into the high temperature furnace tube to deposit a tunneling oxide layer (2); S2.2: SiH4, PH3 and H2 are introduced into the high temperature furnace tube to deposit in-situ doped amorphous silicon (3); S2.3: introducing SiH4 and N2O into the high temperature furnace tube to deposit the first mask layer (4); S2.4: introducing SiH4 into the high temperature furnace tube to deposit intrinsic amorphous silicon (5); S2.5: SiH4 and N2O are introduced into the high temperature furnace tube to deposit a second mask layer (6).

4. The laser grooving method for back contact cells with low laser damage according to claim 1, characterized in that: The laser processing structure in S3 is a stacked structure of a tunneling oxide layer (2), a heavily doped polysilicon (31), a first mask layer (4), an intrinsic polysilicon (51) and a second mask layer (6) stacked in sequence from the inside to the outside on the first surface (101); wherein the tunneling oxide layer (2) has a thickness of 1.2 to 2.0 nm, the heavily doped polysilicon (31) has a thickness of 50 to 300 nm, the first mask layer (4) has a thickness of 1 to 30 nm, the intrinsic polysilicon layer (51) has a thickness of 1 to 200 nm, and the second mask layer (6) has a thickness of 1 to 30 nm.

5. The laser grooving method for back contact cells with low laser damage according to claim 1, characterized in that: S6 includes the following steps: S6.1: First alkaline washing: using KOH chemical solution, etching to remove the intrinsic polysilicon (51) on the second surface (102), as well as the second mask layer (6) and the intrinsic polysilicon (51) in the laser-opened region of the first surface (101); S6.2: First pickling: using HF chemical solution to corrode and remove the first mask layer (4) on the second surface (102) and the first mask layer (4) in the laser-opened region of the first surface (101); S6.3: Second alkaline washing: using KOH chemical solution, etching to remove the heavily doped polysilicon (31) on the second surface (102), the intrinsic polysilicon (51) in the non-laser film-opening area of ​​the first surface (101), and the heavily doped polysilicon (31) in the laser film-opening area of ​​the first surface (101); and partially etching the silicon substrate (1) in the laser film-opening area to form a selective groove on the silicon substrate (1); S6.4: Second pickling: Using HF chemical solution, the first mask layer (4) in the non-laser-opening area of ​​the first surface (101) is corroded and removed to complete the laser grooving.

6. A device, used in S6 of the laser grooving method for a back contact battery with low laser damage as described in any one of claims 1 to 5, comprising a cabinet (8), an acid washing tank (9) and an alkaline washing tank (10) are arranged in the cabinet (8), and a water washing tank (11) is arranged between the acid washing tank (9) and the alkaline washing tank (10), characterized in that: The invention also comprises a transport component, which is arranged in the cabinet (8), and a basket component for loading battery cells is arranged at the lower end of the transport component; the basket component comprises a bracket (12) connected to the transport component and a basket frame (13) rotatably connected to the lower end of the bracket (12); a docking block (14) is arranged at the rotating shaft end of the basket frame (13); a docking component for connecting to the docking block (14) is rotatably arranged in the washing tank (11); and a servo motor (15) for controlling the rotation of the docking component is arranged in the cabinet (8).

7. The device according to claim 6, characterized in that The transport component comprises a crossbeam (16) which is lifted and lowered in a cabinet (8); a slide seat (17) is movably arranged on the crossbeam (16); a slide slot (18) is arranged at the lower end of the slide seat (17); a slide plate (19) is arranged at the upper end of the bracket (12); and the slide plate (19) is arranged to slide into the slide slot (18) with damping.

8. The device according to claim 6, characterized in that The docking assembly comprises a docking seat (20) rotatably arranged on the inner wall of the washing tank (11); a rotating rod (21) coaxially fixedly connected to the docking seat (20) is synchronously rotated at the output end of the servo motor (15); a retaining assembly for limiting the docking block (14) is arranged on the bracket (12); the docking seat (20) can be axially moved and is linked to the descending of the slide seat (17) through a first linkage assembly; when the slide seat (17) descends to the lowest position, the docking block (14) and the docking seat (20) correspond horizontally, and the first linkage assembly links the docking seat (20) to axially move close to the docking block (14) to form a connection to transmit rotation, and the retaining assembly cancels the limit on the docking block (14).

9. The device according to claim 8, characterized in that The first linkage assembly comprises a fork frame (22) movably arranged in a cabinet (8), the fork frame (22) being provided with a sliding groove (23), the rotary rod (21) being sleeved with a synchronous sleeve (24), the side wall of the synchronous sleeve (24) being provided with a sliding pin (25) movably connected to the sliding groove (23), the upper end of the fork frame (22) being connected with a pressing plate (26), the pressing plate (26) being elastically arranged in the cabinet (8) and being in the descending stroke of the slide seat (17).

10. The device according to claim 8, characterized in that The retaining assembly comprises a guide sleeve (27) arranged on the outer side of the lower end of the bracket (12), the guide sleeve (27) being elastically and telescopically connected to a guide block (28) sleeved on the end of the rotating shaft of the flower basket frame (13), and a limit sleeve (29) being fixedly arranged on the guide block (28).

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