A double-sided film coating hollow carrier plate and a plate type ALD film coating equipment
Patent Information
- Application Number
- CN202522106479.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-29
- Publication Date
- 2026-10-13
- Estimated Expiration
- 2035-09-29
AI Technical Summary
但是这样会导致生产过程繁琐，且需要额外增加一倍的机台，设备成本和场地成本升高
[0022]本实用新型的双面镀膜用镂空载板，尤其适合用于板式ALD双面沉积氧化硅膜。该双面镀膜用镂空载板，通过开设空腔来将原来载板的对应基片(如硅片)下表面的封闭处去掉，且每个空腔的内侧壁均设有台阶结构，以供基片的边沿安放于台阶结构上，来实现其对基片的可靠承载；并在空腔的各侧边开设供气体流过的缝隙。如此，通过空腔和缝隙的相互配合，当镂空载板左右来回摆动时，对应区的水蒸汽或TMA会通过缝隙流动至镂空载板的下方，并扩散开；再配合对氧化铝膜沉积工艺的优化，能够在镂空载板的下方形成较低浓度的水蒸汽和TMA分布(也即，镂空载板上方的水蒸汽和TMA的分布浓度大于镂空载板下方的水蒸汽和TMA的分布浓度)，进而在基片的上表面沉积得到较厚的一层氧化铝膜，以实现正面最佳的钝化效果以及更低的UV衰减，并在基片的下表面沉积得到较薄的一层氧化铝膜，以修复gap区钝化，并减少poly区接触损失。
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Abstract
Description
Technical Field
[0001] This utility model relates to the field of solar cell manufacturing technology, specifically to a perforated carrier plate for double-sided coating and a plate-type ALD coating equipment. Background Technology
[0002] Currently, the photovoltaic industry mainly uses two methods for depositing alumina films using ALD (Atomic Layer Deposition): tubular ALD and plate-type ALD. Tubular ALD separates water vapor and TMA (trimethylaluminum) in time: that is, by precisely controlling the pulse timing of the precursors (water vapor and trimethylaluminum), it ensures that the two do not directly contact each other during the reaction, participating in the reaction in stages. When using tubular ALD to deposit alumina films, silicon wafers are inserted into a small boat. If double insertion is selected (two silicon wafers are inserted back-to-back into the boat, with only one side of each wafer exposed to the reaction gas), single-sided alumina deposition can be achieved (i.e., alumina film is deposited on either the front or back of the silicon wafer), but there is wrap-around plating, requiring additional post-processing steps to remove the wrap-around plating. If single insertion is selected (silicon wafers are inserted one at a time, exposing both sides to the reaction gas), double-sided alumina deposition can be achieved (i.e., a layer of alumina film is deposited on both the front and back of the silicon wafer), but the production capacity will be halved.
[0003] In this design, the plate-type ALD spatially separates the water vapor and TMA: that is, by physically isolating the reaction zone, the water vapor and trimethylaluminum (TMA) contact the silicon wafer surface at different spatial locations. When depositing alumina films using a plate-type ALD, the silicon wafer is placed flat on the carrier plate, typically with alumina film deposited on only one side of the wafer. This is because the carrier plate structure currently used for alumina film deposition using plate-type ALDs is as follows: Figure 1-2 As shown, because the substrate body is closed underneath and there are no openings or gaps between the silicon wafers, no aluminum oxide film is deposited under the silicon wafers; only the silicon wafers are deposited with aluminum oxide film.
[0004] Currently, alumina films are mostly used for passivation of p+ emitters, p-silicon substrates, and n-silicon substrates. Their excellent chemical and field passivation effects significantly reduce recombination on the photovoltaic cell surface. For n-type topcon cells (Tunnel Oxide Passivated Contact), in current standard processes, because the back side has complete tox-n+poly (tunnel oxide layer-n+ doped polycrystalline silicon layer) passivation, and if an alumina film were deposited on the back side, it would affect the contact between the n+poly and the metal electrode, requiring additional matching of specific metallization pastes and conditions. Therefore, it is only necessary to deposit an alumina film on the p+ emitter on the textured surface of the cell. Thus, the single-sided coating characteristics of plate-type ALDs are very suitable for the standard process of topcon cells.
[0005] However, for subsequent photovoltaic cell technologies, such as the localized thinning of the n+poly layer on the back of TOPCon cells and their deposition onto a silicon substrate, the passivation of the thinned area will be affected, requiring additional alumina deposition on the back to repair the passivation. For later technologies, such as n-type TBC cells (which combine TOPCon's passivation contact technology with IBC (interdigitated back contact) back electrode design, where the front of the TBC cell has no metal electrode obstruction and the back uses interdigitated metal electrodes for carrier collection), the gap region (isolation region) between the n+poly and p+poly layers (p+-doped polycrystalline silicon layers) on the back also requires additional alumina deposition to repair passivation. When faced with these situations, the single-sided deposition characteristics of plate-type ALDs cannot meet the requirements. At this point, tubular ALD can meet the demand for single-insertion double-sided alumina film deposition, but there is a situation where the production capacity is halved; moreover, when using tubular ALD to deposit alumina film on both sides, the thickness of the obtained front alumina film and the back alumina film is basically the same. However, if the front side is to achieve the best passivation effect, a thicker front alumina film needs to be deposited, which will result in the deposition of an alumina film of the same thickness on the back side. The thicker back alumina film will have a certain negative impact on the contact between the back poly area and the metal electrode.
[0006] For existing ALD (Alternating Current Display) production lines, a temporary solution for upgrading to TBC (Total Cell) production lines is to flip the silicon wafers after depositing the front alumina film to deposit the back alumina film. This allows for the deposition of alumina films of different thicknesses on the front and back sides, thus achieving both passivation and contact performance. However, this results in a cumbersome production process and requires twice the number of machines, increasing equipment and space costs. Utility Model Content
[0007] The purpose of this utility model is to overcome the shortcomings of the prior art and provide a hollow carrier plate for double-sided coating and a plate-type ALD coating equipment.
[0008] Based on this, the present invention discloses a perforated carrier plate for double-sided coating, which includes a carrier plate body; the carrier plate body has a plurality of spaced cavities for supporting a substrate, and the inner sidewall of each cavity is provided with a stepped structure for placing the edge of the substrate.
[0009] Each side of the cavity is provided with at least one slit for the deposition gas to flow through, and the width of the slit is 1-3cm, so that the coating thickness on the front side is greater than that on the back side.
[0010] Preferably, each cavity carries a corresponding substrate, and several cavities are arranged in an array at intervals on the carrier plate body; the substrate is a silicon wafer.
[0011] More preferably, the length of each slit is the same as the length of the substrate; the width of each slit is 2 cm.
[0012] More preferably, each side of the cavity has a first spacer bar separating it from the cavity, and the stepped structure is provided on the inner wall of the first spacer bar facing the cavity.
[0013] More preferably, the first spacer strips surrounding each side of the cavity are connected to each other and then integrally connected to the carrier plate body;
[0014] Along the length of the carrier plate body, there is a gap between two adjacent cavities; and along the width of the carrier plate body, there are two gaps between two adjacent cavities, and these two gaps are spaced apart from each other.
[0015] More preferably, the gaps on each side of each cavity are connected to the adjacent cavities, and a second spacer is provided between two adjacent cavities. The left and right sides of the second spacer extend locally into the corresponding cavities to form extensions that partially block the gaps. The stepped structure is located on the inner wall of the extension facing the cavity.
[0016] More preferably, the second spacers surrounding each side of the cavity are connected to each other and then integrally connected to the carrier plate body;
[0017] Along the length of the carrier plate body, there are two gaps between two adjacent cavities, and these two gaps are separated from each other by a second spacer; along the width of the carrier plate body, there are also two gaps between two adjacent cavities, and these two gaps are also separated from each other by a second spacer.
[0018] More preferably, each of the second spacer bars has an extension at both ends and in the middle, and each extension has a stepped structure.
[0019] More preferably, the width of the extension in the middle of the second spacer gradually decreases from the second spacer side to the cavity side.
[0020] This utility model also discloses a plate-type ALD coating equipment, which includes the perforated carrier plate for double-sided coating described above.
[0021] Compared with the prior art, the present invention has at least the following beneficial effects:
[0022] This invention relates to a perforated carrier plate for double-sided deposition, which is particularly suitable for double-sided deposition of silicon oxide films in plate-type ALD. This perforated carrier plate removes the sealed portion of the corresponding substrate (such as a silicon wafer) on the original carrier plate by creating cavities. Each cavity has a stepped structure on its inner sidewall, allowing the edge of the substrate to rest on the stepped structure for reliable support. Gaps are also created on each side of the cavity to allow gas flow. Thus, through the interaction of cavities and gaps, when the perforated carrier plate swings back and forth, water vapor or TMA in the corresponding area flows through the gaps to the bottom of the perforated carrier plate and diffuses. With the optimization of the alumina film deposition process, a lower concentration of water vapor and TMA can be formed below the perforated carrier plate (that is, the concentration of water vapor and TMA above the perforated carrier plate is greater than that below the perforated carrier plate). This allows a thicker layer of alumina film to be deposited on the upper surface of the substrate to achieve the best passivation effect and lower UV attenuation on the front side, while a thinner layer of alumina film is deposited on the lower surface of the substrate to repair the passivation of the gap area and reduce contact loss in the poly area.
[0023] Therefore, using this perforated carrier plate allows the substrate to obtain a coating of ideal thickness on both the front and back sides. The slightly thicker aluminum oxide film on the front side can achieve better passivation effect and lower UV decay; while the aluminum oxide film on the back side remains slightly thinner, which can balance passivation effect and contact performance, so that the photovoltaic cell can simultaneously obtain higher photoelectric conversion efficiency and lower UV decay.
[0024] Moreover, the perforated carrier plate for double-sided coating of this utility model can make full use of existing plate-type ALD equipment without the need for additional equipment or processes, which can greatly reduce the production cost of double-sided alumina film and photovoltaic cells, and ensure high production capacity. Attached Figure Description
[0025] Figure 1 This is a schematic diagram illustrating the deposition principle of an existing plate-type ALD deposition method for alumina films.
[0026] Figure 2 A top view of the carrier plate used in the existing plate-type ALD.
[0027] Figure 3 This is a schematic diagram illustrating the deposition principle of a plate-based ALD double-sided deposition method for alumina films, as shown in Examples 1-4.
[0028] Figure 4 This is a top view of a perforated carrier plate according to Scheme 1 of this embodiment.
[0029] Figure 5 This is a partial structural diagram of a hollow carrier plate according to Scheme 1 of this embodiment.
[0030] Figure 6 for Figure 5 A partial sectional view.
[0031] Figure 7 This is a top view of another hollowed-out carrier plate in Scheme 2 of this embodiment.
[0032] Figure 8 This is a partial structural diagram of a hollow carrier plate according to Scheme 2 of this embodiment.
[0033] Figure 9 for Figure 8 A partial sectional view.
[0034] Figure 10 This is a schematic diagram of the cross-sectional structure of a TBC battery.
[0035] Reference numerals: 1. Carrier body; 2. Cavity; 3. Stepped structure; 4. Gap; 5. First spacer; 6. Second spacer; 61. Extension; 7. Silicon wafer; 8. Front alumina film; 9. Back alumina film; 10. P-region passivation contact structure; 11. N-region passivation contact structure; 12. Isolation region; 13. Front passivation antireflection film; 14. Back passivation antireflection film; 15. P-region metal electrode; 16. N-region metal electrode. Detailed Implementation
[0036] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0037] Example
[0038] This embodiment describes a method for double-sided deposition of alumina films based on plate-type ALD. See [link to relevant documentation]. Figure 3-9 The process includes the following steps:
[0039] Step 1: Prepare a specially made perforated substrate for double-sided coating of plate-type ALD:
[0040] The perforated carrier plate, see Figure 4-9 The system includes a carrier plate body 1, on which several cavities 2 for supporting a substrate (such as a silicon wafer 7) and several slits 4 for gas flow are formed. Each cavity 2 supports one silicon wafer 7. Several cavities 2 are arranged in an array at intervals on the carrier plate body 1. The inner sidewall of each cavity 2 is provided with a support structure, which is preferably a stepped structure 3, so that the edge of the silicon wafer 7 can be placed on the stepped structure 3 to achieve its support of the silicon wafer 7.
[0041] Each side of the cavity 2 is provided with at least one slit 4 so that gas flows from the top of the cutout carrier plate through the slit 4 and reaches the bottom of the cutout carrier plate, thereby achieving the deposition of aluminum oxide film on the back side (i.e. the lower surface) of the silicon wafer 7.
[0042] The length of each slit 4 is the same as the length of the silicon wafer 7; the width of each slit 4 is 1-3cm, preferably 2cm, to ensure that there is enough gas flow to the bottom of the perforated substrate, which helps to improve the deposition quality of the back aluminum oxide film 9 and helps to control the thickness of the back aluminum oxide film 9.
[0043] Specifically, the arrangement of the gap 4 and the cavity 2 on the carrier plate body 1 can adopt the following two schemes:
[0044] Option 1: See Figure 4-6 Each side of the cavity 2 has a corresponding gap 4 that is spaced apart from the cavity 2. A first spacer 5 separates each gap 4 from the cavity 2, and the stepped structure 3 is located on the inner wall of the first spacer 5 facing the cavity 2. After the first spacer 5 surrounding each side of the cavity 2 is connected to each other, it is integrally connected to the carrier plate body 1 to ensure the stability and reliability of the cavity 2 and the entire hollow structure.
[0045] In practice, there is a gap 4 between two adjacent cavities 2 along the long side (i.e., length) of the carrier plate body 1; and there are two gaps 4 between two adjacent cavities 2 along the narrow side (i.e. width) of the carrier plate body 1, and these two gaps 4 are spaced apart from each other.
[0046] Option 2: See Figure 7-9 Each cavity 2 has gaps 4 on each side that communicate with the adjacent cavity 2, and a second spacer 6 is provided between two adjacent cavities 2. The left and right sides of the second spacer 6 extend partially into the cavity 2 on the corresponding side to form extensions 61 that partially block the gaps 4. The stepped structure 3 is located on the inner wall of the extension 61 facing the cavity 2. After the second spacer 6 surrounding each side of the cavity 2 is connected to each other, it is integrally connected with the carrier plate body 1 to ensure the stability and reliability of the cavity 2 and the entire hollow structure.
[0047] Each of the two ends and the middle of each second spacer 6 is provided with an extension 61, and each extension 61 is provided with a step structure 3; that is, each edge of the silicon wafer 7 has 3 step structures 3 to provide better stable support and load-bearing function for the silicon wafer 7.
[0048] The width of the extension 61 in the middle of the second spacer 6 gradually decreases from the side of the second spacer 6 to the side of the cavity 2. This can ensure the bearing effect of the stepped structure 3 of the extension 61 on the silicon wafer 7 and the stability of the overall structure, and also minimize the area of the extension 61 blocking the gap 4. This ensures that enough gas flows into the back of the silicon wafer 7 through the gap 4, and ensures the deposition area and deposition quality of the back alumina film 9.
[0049] In practice, along the long side (i.e., length) of the carrier plate body 1, there are two gaps 4 between two adjacent cavities 2, and these two gaps 4 are separated from each other by a second spacer 6; moreover, along the narrow side (i.e. width) of the carrier plate body 1, there are also two gaps 4 between two adjacent cavities 2, and these two gaps 4 are also separated from each other by a second spacer 6.
[0050] Thus, by adopting the above two schemes, we can ensure the stability and reliability of the overall structure of the carrier substrate 1, provide stable support and load-bearing for the edge of the silicon wafer 7, and ensure that enough gas flows into the back of the silicon wafer 7 through the gap 4, thus ensuring the deposition area and deposition quality of the back alumina film 9.
[0051] Step 2: Place the silicon wafer 7 into the cavity 2, send the cutout carrier plate into the plate-type ALD device, and introduce reaction gas into the plate-type ALD device so that water vapor zone and TMA zone are alternately distributed from left to right on the upper part of the cutout carrier plate; wherein, the carrier gas is nitrogen, the flow rate of nitrogen is 20-40L / min, the flow rate of TMA is 500-1500mL / min, and the flow rate of water vapor is 500-1500mL / min.
[0052] Step 3: The perforated carrier plate (which carries the silicon wafer 7) is oscillated back and forth in the plate-type ALD equipment to allow the upper surface (i.e., the front side) of the silicon wafer 7 to alternately pass through the water vapor zone and the TMA zone. During the oscillation, the water vapor or TMA in the corresponding zone flows into the lower part of the perforated carrier plate through the gap 4, so that the lower surface (back side) of the silicon wafer 7 alternately contacts the water vapor or TMA. The number of oscillations is 2-10 times, and the deposition temperature is 200-300℃, so as to deposit the front alumina film 8 and the back alumina film 9 on the upper and lower surfaces of the silicon wafer 7, respectively. Through the perforated carrier plate in Step 1 and the process optimization in Steps 2-3, the thickness of the front alumina film 8 is 2-10 times that of the back alumina film 9 (the specific thickness is closely related to the width of the gap 4 of the perforated carrier plate for gas flow and the optimization of process parameters; for example, the wider the gap 4, the greater the gas flow rate, and the longer the number of oscillations, the thicker the alumina film will be).
[0053] When depositing alumina film using a plate-type ALD equipment, water vapor zone and TMA zone are alternately distributed from left to right above the cutout carrier plate. The cutout carrier plate (which carries silicon wafer 7) swings back and forth in the plate-type ALD equipment so that the surface of silicon wafer 7 alternately passes through the water vapor zone and TMA zone.
[0054] The current carrier plate structure used for plate-type ALD deposition of alumina films is as follows: Figure 1-2 As shown, because the substrate is closed underneath and there are no openings in the substrate between silicon wafers 7, no aluminum oxide film is deposited under silicon wafers 7, and only on top of silicon wafers 7.
[0055] The improved hollow carrier plate in this embodiment is as follows: Figure 4-9 As shown, the sealed area on the lower surface of the corresponding silicon wafer 7 of the original carrier plate is removed by creating a cavity 2, and gaps 4 are created on each side of the cavity 2 to allow gas to flow through. In this way, through the interaction of the cavity 2 and the gaps 4, when the cutout carrier plate swings back and forth, water vapor or TMA in the corresponding area will flow through the gaps 4 to the bottom of the cutout carrier plate and diffuse. With the optimization of the alumina film deposition process, a lower concentration of water vapor and TMA can be formed under the cutout carrier plate (that is, the concentration of water vapor and TMA distribution above the cutout carrier plate is greater than that below the cutout carrier plate). As a result, a thicker layer of alumina film is deposited on the upper surface of the silicon wafer 7 to achieve the best passivation effect and lower UV attenuation on the front side, and a thinner layer of alumina film is deposited on the lower surface of the silicon wafer 7 to repair the passivation of the gap area and reduce the contact loss of the poly area.
[0056] This embodiment describes an application of a method for double-sided deposition of alumina film based on plate-type ALD, which is used to produce photovoltaic cells.
[0057] Taking a TBC battery as an example, the method of double-sided deposition of alumina film based on plate ALD in this embodiment is applied to the production of TBC batteries. The resulting TBC battery includes: a silicon wafer 7; a front alumina film 8 and a front passivation antireflection film 13 are sequentially stacked on the upper surface of the silicon wafer 7; the lower surface of the silicon wafer 7 includes a p region, an n region, and an isolation region 12 separating the p region and the n region; the p region of the lower surface of the silicon wafer 7 is sequentially provided with a p region passivation contact structure 10, a back alumina film 9, a back passivation antireflection film 14, and a p region metal electrode 15, and the p region metal electrode 15 is in ohmic contact with the p region passivation contact structure 10; the n region of the lower surface of the silicon wafer 7 is sequentially provided with an n region passivation contact structure 11, a back alumina film 9, a back passivation antireflection film 14, and an n region metal electrode 16, and the n region metal electrode 16 is in ohmic contact with the n region passivation contact structure 11; and the isolation region 12 of the lower surface of the silicon wafer 7 is sequentially provided with a back alumina film 9 and a back passivation antireflection film 14. The back passivation antireflection film 14 and the front passivation antireflection film 13 are both at least one of silicon nitride film, silicon oxynitride film, and silicon oxide film (the following embodiments use silicon oxynitride film). The p-region passivation contact structure 10 includes a tunneling oxide layer and a p+poly layer (i.e., a p+ doped polysilicon layer) sequentially deposited on the lower surface of the silicon wafer 7; while the n-region passivation contact structure 11 includes a tunneling oxide layer and an n+poly layer (n+ doped polysilicon layer) sequentially deposited on the lower surface of the silicon wafer 7.
[0058] This embodiment provides a plate-type ALD coating equipment, which includes a double-sided coating perforated carrier plate as described in step 1 of this embodiment.
[0059] The following provides a specific example of a method for double-sided deposition of alumina films based on plate-type ALD in this embodiment, and its application:
[0060] Examples 1-4 and Comparison Example 1
[0061] Examples 1-4 illustrate a method for double-sided deposition of alumina films using a plate-type ALD, with process steps referring to steps 1-3 of the specific embodiments described above. Examples 1-4 all employ the perforated carrier plate of Scheme 2, and the specific process conditions for double-sided deposition of alumina films using a plate-type ALD in Examples 1-4 are shown in Table 1 below.
[0062] In Examples 1-4, the width of the slit 4 in the perforated carrier plates is 2 cm. The gas (TMA, H2O, N2) flow rates of Examples 1 to 4 increase sequentially to achieve the deposition of double-sided alumina films through plate ALD (the thickness of the front alumina film 8 is greater than the thickness of the back alumina film 9).
[0063] Example 1-4 illustrates an application of a method based on plate-type ALD double-sided deposition of alumina films, used to fabricate TBC cells, the structure of which is as follows: Figure 10 As shown.
[0064] Comparing Example 1, a method for double-sided deposition of alumina film based on plate-type ALD is described. The process steps are the same as in Example 1, except that the method is replaced with... Figure 1-2 The sealing carrier plate shown.
[0065] Comparing the application of a method based on plate-type ALD double-sided deposition of alumina film in Example 1, this method is applied to the fabrication of a TBC battery, the structure of which is as follows: Figure 10 As shown.
[0066] Table 1 Process conditions for plate-type ALD double-sided deposition of alumina films
[0067] Compare Example 2-3
[0068] Comparative Examples 2-3 illustrate a method for double-sided deposition of alumina films using a tubular ALD (Alternating Discharge) system. The carrier is a small boat, and the deposition method is single-insertion double-sided deposition. By varying the number of cycles and the specific process conditions (as shown in Table 2), alumina films of different thicknesses are obtained (the front and back alumina films have the same thickness). In Table 2, Comparative Examples 2 and 3 use the same tubular ALD equipment, differing only in the number of cycles during deposition.
[0069] Comparing the application of a method based on tubular ALD double-sided deposition of alumina film in Examples 2-3, this method is applied to the fabrication of TBC cells, the structure of which is as follows: Figure 10 As shown.
[0070] Table 2 Process conditions for tubular ALD double-sided deposition of alumina films
[0071] Performance testing
[0072] Performance tests were conducted on silicon wafers and TBC cells with double-sided deposited alumina films in Examples 1-4 and Comparative Examples 1-3. The test results are shown in Table 3-4 below:
[0073] Table 3. Test results of double-sided alumina film thickness, passivation performance, and contact performance.
[0074]
[0075] Table 3 shows the front and back alumina film thicknesses of the TBC batteries prepared in Examples 1-4 and Comparative Examples 1-3, the composite current density J0 (lower is better) characterizing the passivation level, and the contact resistivity ρc (lower is better) characterizing the contact condition.
[0076] Based on the test data in Table 3, we can conclude that:
[0077] (1) In Examples 1-4 (plate-type ALD + specially designed perforated carrier plate), as the gas (TMA, H2O, N2) flow rate increases, the thickness of the front and back alumina films increases, and the thickness of the front alumina film is less than that of the back alumina film. Its J0 decreases and the back ρc increases slightly, which can better balance its passivation performance and contact performance. However, the thickness of the front and back alumina films should not be too thick. The thickness of the front alumina film should be controlled in the range of 3-10nm (preferably 7nm), while the thickness of the back alumina film should be controlled in the range of 1-6nm (preferably 1-4nm, more preferably 3nm) to ensure that ideal front and back alumina film thicknesses and better battery performance are obtained.
[0078] (2) In contrast, Example 1 uses a plate-type ALD+ sealed carrier plate, and there is no aluminum oxide film on the back of the silicon wafer, which leads to a significant increase in J0 of the battery, greatly affecting the passivation performance of the battery.
[0079] (3) For tubular ALD, since the aluminum oxide film deposited on the front and back of the silicon wafer is of the same thickness, if the aluminum oxide film deposited on both sides is thicker, the ρc on the back of the battery will increase significantly, which will greatly affect the contact performance of the battery.
[0080] Table 4. Electrical performance of TBC cells with aluminum oxide films deposited on both the front and back sides of the silicon wafer.
[0081] Compare with Example 1 (Sealed Carrier Plate) 26.98 0.738 14.250 84.91 1.2％ Example 1 (Perforated Carrier Plate) 27.08 0.740 14.260 84.90 1.2％ Example 2 (Perforated Carrier Plate) 27.10 0.741 14.265 84.87 1.1％ Example 3 (Perforated Carrier Plate) 27.14 0.742 14.267 84.85 1.0％ Example 4 (Perforated Carrier Plate) 27.12 0.743 14.267 84.69 0.9％ Compare with Example 2 (Tube ALD 1) 27.08 0.741 14.260 84.84 2.9％ Compare with Example 3 (Tube ALD 2) 26.52 0.742 14.231 83.14 1.0％
[0082] Table 4 shows the electrical performance data of the prepared TBC batteries (the TBC batteries in Tables 3-4 are TBC batteries with commonly used standard structures. The TBC batteries in Examples 1-4 and Comparative Examples 1-3 are different only in the aluminum oxide film).
[0083] Where Eta is the photoelectric conversion efficiency of the battery (referred to as battery efficiency), Uoc is the open-circuit voltage, Isc is the short-circuit current, FF is the fill factor, and UV decay is the ultraviolet decay.
[0084] Based on the test data in Table 3-4, we can conclude that:
[0085] (4) In Examples 1-4 (plate-type ALD + specially designed hollow carrier plate), as the gas flow rate increases, the thickness of the alumina film on both the front and back sides increases, the passivation level increases, and Uoc and Isc increase; the impact on the contact on the back of the battery is small, and FF only decreases slightly. Among them, Example 3 has the best overall performance, with a front alumina film thickness of 7nm and a back alumina film thickness of 3nm, achieving the best balance between passivation performance and contact performance; thus, the battery efficiency of Example 3 is increased by 0.16% compared to the comparative Example 1, and its UV decay is reduced by 0.2%.
[0086] As can be seen, this embodiment is designed for plate-type ALDs and uses a specially designed perforated carrier plate to achieve double-sided deposition with a front alumina film thickness greater than the back alumina film thickness. This allows the alumina film deposited on the back to repair the passivation of the gap area, and the thinner back alumina film has less impact on the contact of the poly area. It also allows the front alumina film to be slightly thicker, which has advantages in passivation and resistance to UV fading.
[0087] (5) For tubular ALDs, since only aluminum oxide films of the same thickness can be deposited on both the front and back sides at the same time, they cannot have the same passivation and contact performance as in this embodiment:
[0088] Compared to the tubular ALD 1 battery sample in Comparative Example 2, the thickness of the front alumina film is 3 nm, and the thickness of the back alumina film is 3 nm. Compared to Example 3, the front alumina film of Comparative Example 2 is thinner, resulting in decreased passivation performance, a 0.06% decrease in battery efficiency, and a 1.9% increase in UV decay.
[0089] Compared to the tubular ALD2 battery sample in Example 3, both the front and back aluminum oxide films were made thicker (the front aluminum oxide film was 6nm thick and the back aluminum oxide film was 6nm thick). Because the back aluminum oxide film was too thick, it had a greater impact on the contact on the back of the battery, so the battery efficiency of Example 3 was significantly reduced.
[0090] Therefore, this embodiment of a method for double-sided deposition of alumina films based on a plate-type ALD, combined with a specially designed perforated carrier plate structure and optimized deposition process of the double-sided alumina film on the plate-type ALD, achieves a special double-sided alumina film structure on the photovoltaic cell where the front alumina film is slightly thicker and the back alumina film is slightly thinner, so that both the front and back alumina films achieve a relatively ideal thickness. Thus, the slightly thicker front alumina film can achieve better passivation and lower UV attenuation; while maintaining a slightly thinner back alumina film can balance passivation and contact performance, thereby enabling the photovoltaic cell to simultaneously achieve higher photoelectric conversion efficiency and lower UV attenuation.
[0091] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.
[0092] The technical solution provided by this utility model has been described in detail above. Specific examples have been used to illustrate the principle and implementation of this utility model. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.
Claims
1. A perforated carrier plate for double-sided coating, characterized in that, It includes a carrier plate body; the carrier plate body has a number of spaced cavities for supporting the substrate, and the inner sidewall of each cavity is provided with a stepped structure for placing the edge of the substrate. Each side of the cavity is provided with at least one slit for the deposition gas to flow through, and the width of the slit is 1-3cm, so that the coating thickness on the front side is greater than that on the back side.
2. The perforated carrier plate for double-sided coating according to claim 1, characterized in that, Each cavity corresponds to a substrate, and several cavities are arranged in an array at intervals on the carrier plate body; the substrate is a silicon wafer.
3. A perforated carrier plate for double-sided coating according to claim 1 or 2, characterized in that, The length of each slit is the same as the length of the substrate; the width of each slit is 2 cm.
4. A perforated carrier plate for double-sided coating according to claim 1 or 2, characterized in that, The cavity has a first spacer bar separating each side of the cavity from the corresponding gap, and the stepped structure is provided on the inner wall of the first spacer bar facing the cavity.
5. A perforated carrier plate for double-sided coating according to claim 4, characterized in that, After the first spacer strips surrounding each side of the cavity are connected to each other, they are integrally connected with the carrier plate body; Along the length of the carrier plate body, there is a gap between two adjacent cavities; and along the width of the carrier plate body, there are two gaps between two adjacent cavities, and these two gaps are spaced apart from each other.
6. A perforated carrier plate for double-sided coating according to claim 1 or 2, characterized in that, Each cavity has gaps on each side that communicate with adjacent cavities, and a second spacer is provided between two adjacent cavities. The left and right sides of the second spacer extend locally into the corresponding cavities to form extensions that partially block the gaps. The stepped structure is located on the inner wall of the extension facing the cavity.
7. A perforated carrier plate for double-sided coating according to claim 6, characterized in that, After the second spacers surrounding each side of the cavity are connected to each other, they are integrally connected to the carrier plate body; Along the length of the carrier plate body, there are two gaps between two adjacent cavities, and these two gaps are separated from each other by a second spacer; along the width of the carrier plate body, there are also two gaps between two adjacent cavities, and these two gaps are also separated from each other by a second spacer.
8. A perforated carrier plate for double-sided coating according to claim 6, characterized in that, Each of the second spacers has an extension at both ends and in the middle, and each extension has a stepped structure.
9. A perforated carrier plate for double-sided coating according to claim 8, characterized in that, The width of the extension in the middle of the second spacer gradually decreases from the second spacer side to the cavity side.
10. A plate-type ALD coating equipment, characterized in that, It includes a perforated carrier plate for double-sided coating as described in any one of claims 1-9.