Vacuum deposition device

Abstract

A vacuum deposition device, comprising: a reaction chamber (1), which is used for performing deposition; a sprayer (2), which is disposed at an upper part of the reaction chamber (1); a rotating apparatus (3), which is disposed at a bottom part of the reaction chamber (1); a tray (4), which is arranged above the rotating apparatus (3), is opposite the sprayer (2), and is used for placing a plurality of tools (A); heaters (5), which are disposed at a bottom part and on side surfaces of the tray (4) and each internally comprise a heating component; and a gas path system, which is connected to the sprayer (2) to provide a reactant for performing deposition. In the heaters provided on the side surfaces, the heating strength increases as the height increases from the bottom to the top. According to the described vacuum deposition device, passivation of a side section of a cut battery cell is achieved, and the efficiency of a battery assembly is improved. Moreover, the technical problem of yield loss caused by poor welding of the battery assembly due to a passivation film windingly plating a front surface or back surface of a battery is avoided, and the power generation costs of the assembly are reduced.

Description

Vacuum coating equipment Technical Field

[0001] The present application relates to the field of solar cells, and in particular to a vacuum coating device. Background Art

[0002] In recent years, with the rise of new module technologies such as half-cut and shingled modules, the production of modules requires splitting a single cell into two or more pieces. For industrial applications, methods for splitting solar cells typically include laser scribing with mechanical cleavage and thermal laser low-damage cleavage. The surface recombination rate at the split cell section is very high, significantly impacting the solar cell's electrical performance. For example, after laser scribing a Topcon solar cell in half, the conversion efficiency of the half cell decreases by 0.2-0.3% due to increased edge recombination. Heterojunction solar cells have a higher open-circuit voltage, and the efficiency decreases even more after laser cleavage. The reduced solar cell efficiency caused by laser cleavage directly leads to a reduction in module power.

[0003] Passivation coating is a process that deposits a passivation film on the cell surface, reducing minority carrier recombination, providing field passivation, and lowering reflectivity. As N-type silicon wafer quality and cell efficiency continue to improve, cutting losses are also increasing, making passivation coating of the cell surface after slicing even more important.

[0004] In order to improve production efficiency, the battery cells need to be stacked and then cross-sectioned and passivated. However, the height of the metal grid lines on the front and back of the printed battery cells is usually 10-30μm. The presence of these metal grid lines causes gaps between the stacked battery cells. At this time, if the existing coating technology is used, the passivation repair film will extend into the gaps between the battery cells. This phenomenon is called wrap-around plating. The wrap-around coating film is deposited on the welding points on the front and back of the battery cells, resulting in poor contact and affecting the yield of the battery assembly made of such battery cells. Figure 1 is a schematic diagram of a battery cell after coating using the vacuum coating equipment of the prior art. As shown in Figure 1, although the wrap-around plating phenomenon in the prior art has been reduced to a certain extent, it is still very serious.

[0005] One existing solution to the problem of wrap-around plating is to slice and passivate the cells before printing, allowing for wrap-around plating without affecting the solder joints on the cell surface. However, this approach presents the following technical challenges: 1) Cells without gridlines can be scratched by friction; 2) shingling cells (half-cells or smaller) significantly reduces the capacity of the printing line, increasing production line investment and resulting in excessive costs.

[0006] It can be seen that whether it is possible to provide an improved large-scale mass production equipment for passivation coating of cell sections, especially for cell sections used in half-cut modules or shingled modules, based on the deficiencies in the existing technology, has become a technical problem that needs to be urgently solved by those skilled in the art.

[0007] Summary of the Invention

[0008] The present application aims to overcome the shortcomings of the prior art and provide a vacuum coating device. The vacuum coating device provided by the present application effectively improves the efficiency of solar cells. Another object of the present application is to significantly reduce the adverse effects of wrap-around coating, improve the efficiency and yield of corresponding solar cell modules, and reduce the cost of module power generation.

[0009] The present application relates to a vacuum coating device, comprising:

[0010] A reaction chamber for coating;

[0011] Spray, located at the upper part of the reaction chamber;

[0012] A rotating device is provided at the bottom of the reaction chamber;

[0013] A tray is provided above the rotating device and opposite to the spraying device, and is used to place multiple tools for holding cut solar cells;

[0014] a heater disposed on the bottom and sides of the tray and including heating elements therein;

[0015] A gas system connected to the spray to provide reactants for coating;

[0016] The exhaust system is used to ensure the vacuum degree of the reaction chamber and the stability of the reaction gas flow.

[0017] For heaters located on the side, the heating intensity increases as the height increases from the bottom to the top.

[0018] Preferably, the device is used to coat the side sections of the cut solar cells, wherein the solar cells are stacked in the tooling with a height of 0.5-30 cm.

[0019] Preferably, the tooling is a wafer box with a processing window on the side, and the battery cells in the wafer box are stacked with a height of 1-30 cm.

[0020] Preferably, the tray is made of graphite or metal, and the number of the cassettes is greater than or equal to 2, more preferably greater than 4, and most preferably greater than 8.

[0021] Preferably, the reaction chamber is a circular chamber and comprises an upper cover, a side portion, and a bottom portion.

[0022] Preferably, a heater is also provided on the upper cover.

[0023] Preferably, a valve opening is provided on the side of the reaction chamber, which is connected to the transmission system through the valve opening, and the operation is performed between the valve opening and the transmission system through the transmission mechanism.

[0024] Preferably, the transmission mechanism is a gripper, which is adapted to the tooling to move the tooling.

[0025] Preferably, it also includes a fixing device provided on the rotating device and the tray,

[0026] The rotating device includes a rotating shaft and a motor.

[0027] Preferably, the processing window of the cassette is perpendicular or parallel to the upper surface of the tray.

[0028] Preferably, it is connected to a buffer area that is isolated from air,

[0029] After coating is completed, the transfer mechanism grabs the tooling and places it in the buffer area for cooling.

[0030] Preferably, it also includes a heat source for maintaining the temperature between the spray and the upper cover to assist in coating.

[0031] Compared with the prior art, this application has the following advantages:

[0032] The vacuum coating equipment provided in this application can reduce the conversion efficiency loss caused by cell cutting, and can also significantly reduce the adverse effects caused by wrap-around plating, thereby improving the efficiency of cell modules and reducing the cost of module power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a schematic diagram of a cell after being coated using vacuum coating equipment in the prior art.

[0034] FIG2 is a schematic structural diagram of the vacuum coating equipment of the present application.

[0035] FIG3 is a schematic diagram of a film box in a vacuum coating device.

[0036] FIG4 is a schematic diagram of the arrangement of the film cassettes in the vacuum coating equipment.

[0037] FIG5 is another schematic diagram of the arrangement of the film cassettes in the vacuum coating equipment.

[0038] FIG. 6 is a schematic diagram of a cell after being coated using the vacuum coating equipment in FIG. 2 . DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the following embodiments are only some specific implementation methods of the present application, but not all embodiments. The following exemplary embodiment descriptions are only illustrative and do not limit the present application and its application or use. Based on the description of this application, all other technical solutions obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0040] For ease of description, this application uses spatially relative terms, such as "above", "above", "on the upper surface of", "above", etc., to describe the spatial positional relationship of a device or feature with other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above" or "above" will be positioned as "below" or "below". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0041] As shown in FIG2 , the present application discloses a vacuum coating device, including a reaction chamber 1 , a spray 2 , a rotating device 3 , a tray 4 , a heater 5 , and a gas path system.

[0042] As shown in Figure 2, the reaction chamber 1 is preferably a circular chamber, but is not limited thereto and may be of other shapes according to actual needs. The reaction chamber 1 shown in Figure 2 is composed of an upper cover 6, side parts 7, and a bottom 8, but may also include other components as needed.

[0043] Spray 2 is a showerhead that uses a downward spray mode (showerhead), and together with the gas system, provides reactants for side-section passivation coating. The gas system preferably includes: a first deposition gas pipeline, a second deposition gas pipeline, and a purge / supplementary gas pipeline. The gas system also preferably includes a temperature control and rehydration system. The first deposition gas pipeline (the second deposition gas pipeline) is composed of, for example, an MFC (gas flow controller), a source bottle, a pneumatic valve, a connecting pipeline, etc., and may also include a PC (pressure controller). The purge / supplementary gas pipeline is composed of, for example, an MFC (gas flow controller), a pneumatic valve, a connecting pipeline, etc.

[0044] As shown in Figure 2, the rotating device 3 is arranged at the bottom of the reaction chamber 1. The rotating device 3 preferably includes a rotating shaft and a motor, but may also include other components as needed. The tray 4 is arranged above the rotating device 3, and the bottom of the tray 4 is connected to the rotating device 3, and the rotating device 3 causes the tray 4 to rotate. In the reaction chamber 1, the tray 4 is opposite to the spray 2, that is, the lower surface (gas outlet surface) of the spray 2 shown in Figure 2 is arranged relative to the upper surface of the tray 4. The material of the tray 4 is preferably graphite, metal or the like, but is not limited thereto, and any other suitable material can also be used according to actual circumstances. Multiple tooling A can be placed on the tray 4. The spacing between the lower surface of the spray 2 and the upper surface of the tray 4 can be 1.0-50cm, and the height of the tooling A is preferably 0.5-30cm, so the spacing between the upper end surface of the tooling A and the lower surface of the spray 2 can be 0.5-20cm.

[0045] Preferably, the vacuum coating equipment is used to perform passivation coating on the side sections of the cut solar cells, but this is not limited to this. Other coating methods can also be performed as needed. Preferably, the tool A is a wafer box with a processing window on the side, but this is not limited to this. It can also be other suitable devices for coating. When performing passivation coating on the side sections of the solar cells, the wafer box is used to place the cut solar cells that need to be passivated and protect the solar cells. Each wafer box can, for example, stack 10-2000 cut solar cells, preferably 200-600 cells. The solar cells in the wafer box are as close to each other as possible while ensuring that they are not damaged. As shown in Figure 3, a processing window is provided on the side of the tool so that the side sections of the solar cells are exposed to the passivation coating atmosphere for passivation during coating. The number of wafer boxes is 2 or more, preferably 4 or more, more preferably 8 or more, or any number based on actual needs. The solar cells in the wafer box are stacked, and the height is preferably 1-30 cm.

[0046] The tooling A, such as a wafer cassette, can be positioned within the reaction chamber at any angle and in any manner suitable for coating. The processing window of the wafer cassette can be perpendicular or parallel to the upper surface of the tray 4, or at any angle in between. The tooling, such as the wafer cassette, can be positioned on the tray 4 in a variety of ways, such as with the side section of the cell facing the center of the tray, facing away from the center of the tray, rotating the windward side, or rotating the leeward side. The placement angle can be, for example, perpendicular to the plane of the tray.

[0047] The total number of cells in the cassettes placed on tray 4 can reach several thousand, and the combined weight of tray 4, cassettes, and cells can reach 100 kg or more. In this case, rotating device 3 is equipped with a drive device sufficient to ensure rotation. Preferably, when the weight of the cassettes and cells exceeds 10 kg, it also includes a fixing device capable of securing the tray to the rotating device to ensure stable rotation of tray 4.

[0048] Heaters 5 are installed at the bottom and sides of tray 4 to maintain the reaction temperature. Heaters 5 contain heating elements. The bottom and side heaters 5 are preferably integrated. The bottom heater 5 can preferably heat the reaction chamber to 450°C or higher. The side heaters 5 can preferably achieve uniform heating across the vertical height. For example, the heating intensity of the heater 5 increases with increasing height from the bottom to the top, for example, the number of heating elements increases with increasing height. The heating elements can be, for example, resistance wires or any other suitable components. Preferably, the temperature difference between the lower and upper surfaces of the fixture A containing the battery cells is within 5 degrees. More preferably, as shown in Figure 2, a heater 5 is also installed below the upper cover 6 to enhance uniform heating within the reaction chamber 1. However, this is not limiting and the heater 5 can also be omitted below the upper cover 6.

[0049] Preferably, a valve opening is provided on the side 7 of the reaction chamber 1, which is connected to a transport system through the valve opening. A transport mechanism operates between the valve opening and the transport system, such as a conveyor belt. The transport mechanism is preferably a gripper, such as a cantilever gripper, which places a cassette containing unpassivated cells into the tray 4 and removes a cassette containing passivated cells from the tray 4. The cantilever gripper is adapted to the cassette to achieve the desired movement of the cassette within the reaction chamber, including but not limited to lifting, lowering, or parallel translation of the cassette.

[0050] Preferably, there is a buffer area connected to the vacuum coating equipment that can be isolated from air. After the coating is completed, the conveying mechanism grabs the tooling and places it in the buffer area for cooling.

[0051] In addition, an exhaust system 9 is provided to exhaust gases generated during the passivation coating process. Exhaust system 9 is connected to a vacuum pump to ensure the vacuum level of the chamber. Exhaust system 9 includes an exhaust device located at the bottom 8 and an exhaust channel located at the side 7. The exhaust device ensures that the airflow is basically stable under reaction conditions and there are no dead zones. As shown in Figure 2, the exhaust channel is at substantially the same height as the tray 4.

[0052] Preferably, as shown in FIG2 , a heat source 10 for maintaining the temperature is further included between the shower 2 and the upper cover 6 , for generating plasma to assist in film deposition. The heat source 10 for maintaining the temperature, for example, can be a heater, and can assist in film deposition methods such as ALD. However, the heat source 10 for maintaining the temperature is not required and may not be provided.

[0053] In addition, a power supply device is provided to supply power to the entire passivation vacuum coating equipment. The power supply device is preferably an electrical cabinet, but may also be other suitable power supply devices.

[0054] After the aforementioned preferred side-section passivation coating is completed using the aforementioned vacuum coating equipment, the film thickness is 55-100 nm, preferably 40-60 nm, and the film material includes aluminum oxide. Testing has shown that the efficiency of the cell is significantly improved after the passivation coating of this application. For example, the efficiency of a cell module consisting of 144 cells measuring 182 mm x 91 mm is increased by over 6 W.

[0055] The present application is further described below based on examples.

[0056] Example 1

[0057] The coating apparatus includes a circular reaction chamber 1, a sprayer 2 with an upper spray mode, a rotating device 3 including a rotating shaft and a motor, a graphite tray 4, heaters 5 located on the bottom and sides of the tray 4, and a gas system. The circular reaction chamber 1 consists of an upper cover 6, side panels 7, and a bottom 8. There are no valve openings on the side panels 7 of the circular reaction chamber 1. The heaters 5 located on the bottom and sides of the tray 4 are separate components, and the apparatus does not include a heat source for heat retention.

[0058] First, cut the printed and sintered cells in half, align the side cuts, and place them in eight cell cassettes. Stack them tightly, ensuring they do not damage the cells. Each cassette holds 10 cells. Place the cassettes containing the cells in the area to be passivated. Then, place the eight cassettes from the area to be passivated onto tray 4 and arrange them as shown in Figure 4. The gap between the lower surface of spray 2 and the upper surface of tray 4 is 11 cm. The height of the cassettes is 10 cm, and the gap between the upper surface of the cassettes and the lower surface of spray 2 is 1 cm.

[0059] The reactants are TMAl (trimethylaluminum) and H2O, and the carrier gas is N2, which enters the reaction chamber through the gas system. TMAl and H2O flow into the gas system through a centralized liquid supply method. After N2 enters the gas system, TMAl and H2O will be carried out according to the saturated vapor pressure and the principle of the bubbling method and enter the reaction chamber 1. TMAl and H2O use N2 as the carrier gas and undergo a CVD reaction after entering the reaction chamber 1. The process reaction time is 5 minutes, and the passivation film formed on the side section is Al2O3 with a thickness of 35nm. During the reaction, the reaction temperature is 200°C, the flow rate of N2 carrying TMAl is 500sccm, the flow rate of N2 carrying H2O is 300sccm, the flow rate of N2 purge gas is 5slm, and the chamber pressure is 20Torr.

[0060] After the side section passivation coating is completed, all 8 cassettes are placed from tray 4 into the passivated area.

[0061] After the side-section passivation coating was completed using the coating device of Example 1, the cell was tested to have almost no wrap-around coating as shown in FIG6 . The front side was wrapped around 0.7 mm, and the back side was wrapped around 0.5 mm. Furthermore, no dark spots of EL appeared in the 72-cell module.

[0062] Example 2

[0063] The apparatus used in Example 2 is similar to that in Example 1, except that a valve opening is provided on the side 7 of the circular reaction chamber 1, which is connected to the conveyor belt through the valve opening. The heater 5 located on the bottom of the tray 4 and the heater 5 located on the side of the tray 4 are integrated and equipped with a fixing device.

[0064] First, stack the halved battery cells and place them in 12 cell boxes. Stack them tightly without damaging the battery cells. Each cell box is loaded with 500 battery cells. The cell boxes containing the battery cells are placed in the area to be passivated. Then, place the 12 cell boxes from the area to be passivated onto the tray 4. Figure 5 shows how the 12 cell boxes are placed. The distance between the lower surface of the spray 2 and the upper surface of the tray 4 is 10.8 cm, the height of the cell box is 10 cm, and the distance between the upper surface of the cell box and the lower surface of the spray 2 is 0.8 cm. Through the valve opening, the cantilever gripper places the cell box containing the unpassivated cell cells from the area to be passivated into the tray 4, and takes the cell box containing the passivated cell cells out of the tray 4. The cantilever gripper is adapted to the cell box to move the cell box, and can lift, put down, and move the cell box back and forth.

[0065] The reactants are TMAl and H2O, and the carrier gas is N2, which enters the reaction chamber through the gas system. TMAl and H2O flow into the gas system through a centralized liquid supply method. After N2 enters the gas system, TMAl and H2O will be carried out according to the saturated vapor pressure and the principle of the bubbling method and enter the reaction chamber 1. TMAl and H2O use N2 as the carrier gas and undergo a CVD reaction after entering the reaction chamber 1. The reaction time is 20 minutes, and the passivation film formed is Al2O3 with a thickness of 50nm. During the reaction process, the reaction temperature is 250°C and the chamber pressure is 5Torr. After completing the Al2O3 deposition, annealing is also carried out for 30 minutes at an annealing temperature of 300°C.

[0066] After the side section coating is completed, all 12 cassettes are placed from tray 4 into the passivated area.

[0067] After the side section is coated using the coating device of Example 2, there is almost no wrap-around coating as shown in FIG6 . The front side is coated at 0.5 mm and the back side is coated at 0.4 mm. The size of the side section after passivation is 182 mm × 91 mm. The absolute value of the power of the 144-piece module (72-plate type) packaged by these half-cell batteries is increased to 6W.

[0068] While the embodiments of the present application have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations may be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present application as set forth in the claims. Furthermore, the present application described herein may have other embodiments and may be implemented or carried out in a variety of ways.

Claims

1. A vacuum coating device, characterized in that: include: A reaction chamber for coating; Spray, located at the upper part of the reaction chamber; A rotating device is arranged at the bottom of the reaction chamber; A tray, arranged above the rotating device and opposite to the spray, is used to place a plurality of tools for holding cut battery cells; A heater, disposed on the bottom and sides of the tray and including heating elements therein; A gas system connected to the spray to provide reactants for coating; The exhaust system is used to ensure the vacuum degree of the reaction chamber and the stability of the reaction gas flow. For the heater installed on the side, the heating intensity increases with the height from the bottom to the top. The vacuum coating equipment is used to coat the side cut surfaces of the cut battery cells.

2. The vacuum coating equipment according to claim 1, characterized in that: The battery sheets are stacked in the tooling with a height of 0.5-30 cm.

3. The vacuum coating equipment according to claim 2, characterized in that: The tooling is a wafer box with a processing window on the side. The battery cells in the wafer box are stacked with a height of 1-30cm.

4. The vacuum coating equipment according to claim 3, characterized in that: The material of the tray is graphite or metal, and the number of the film boxes is greater than or equal to 2.

5. The vacuum coating equipment according to claim 1, characterized in that: The reaction chamber is a circular chamber and comprises an upper cover, a side portion and a bottom portion.

6. The vacuum coating equipment according to claim 5, characterized in that: A heater is also provided under the upper cover.

7. The vacuum coating equipment according to claim 5, characterized in that: A valve opening is arranged on the side of the reaction chamber, which is connected with the transmission system through the valve opening, and the transmission mechanism operates between the valve opening and the transmission system.

8. The vacuum coating equipment according to claim 7, characterized in that: The transmission mechanism is a gripper, which is matched with the tooling to move the tooling.

9. The vacuum coating equipment according to claim 1, characterized in that: Also includes a fixing device provided on the rotating device and the tray, The rotating device includes a rotating shaft and a motor.

10. The vacuum coating equipment according to claim 3, characterized in that: The processing window of the film box is perpendicular or parallel to the upper surface of the tray.

11. The vacuum coating equipment according to claim 7, characterized in that: Connected to the air-isolated buffer area, After coating is completed, the transfer mechanism grabs the tooling and places it in the buffer area for cooling.

12. The vacuum coating equipment according to claim 5, characterized in that: It also includes a heat source for maintaining, which is arranged between the spray and the upper cover and is used to maintain the temperature so as to assist the coating.

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