TOPCon battery and preparation method thereof
By forming a spaced-distributed tunneling oxide layer in the TOPCon battery and using a mixture of N2O and argon gas during the PECVD process, the problem of tunneling oxide layer thickness control is solved, and the efficient photoelectric conversion and temperature tolerance of the battery are achieved.
Patent Information
- Application Number
- CN202411583129.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-07
- Publication Date
- 2025-02-21
AI Technical Summary
How to control the thickness of the tunneled oxide layer to balance its passivation and contact ability and improve the photoelectric conversion efficiency.
By forming a tunneling oxide layer of the first and second regions spaced apart on the back of the substrate of the TOPCon battery, the thickness of the first region is greater than the thickness of the second region, and the second region is passed through when the second tunneling oxide layer is deposited by a PECVD device. A mixture of N2O gas and argon gas improves the proportion and density of oxygen atoms.
It has achieved both the passivation and contact capabilities of the battery, improved the photoelectric conversion efficiency, and improved the temperature tolerance of the tunneled oxide layer, expanding the process window.
Smart Images
Figure CN119497461A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of solar cells, and specifically provides a TOPCon cell and a preparation method thereof. Background Art
[0002] TOPCon (tunneling oxide passivated contact) batteries are currently widely used in the industry because of their unique tunneling properties through the tunneling oxide layer, which can significantly reduce the recombination of electrons and holes, greatly increase the open circuit voltage and current density of the battery, and thus improve the photoelectric conversion efficiency.
[0003] However, combined with practical applications and research, it is found that when the tunnel oxide layer has a high thickness, it has a strong blocking ability for doped atoms and is easy to ensure high passivation performance. However, the increase in the thickness of the tunnel oxide layer will lead to an increase in contact resistance, affecting the contact performance. On the contrary, when the thickness of the tunnel oxide layer is thin, the contact performance is improved, but the passivation performance is reduced. Therefore, when the tunnel oxide layer is too thin or too thick, it will affect the overall performance of the battery, resulting in the battery's photoelectric conversion efficiency being affected.
[0004] Therefore, how to control the thickness of the tunnel oxide layer to balance its passivation ability and contact ability has become a technical problem that needs to be solved urgently in this field. Summary of the invention
[0005] The present application aims to solve the above technical problem, that is, to solve the problem of how to control the thickness of the tunneling oxide layer to improve the photoelectric conversion efficiency.
[0006] In a first aspect, the present application provides a TOPCon battery, comprising:
[0007] a substrate comprising a front surface and a back surface opposite to the front surface;
[0008] A tunneling oxide layer, a polysilicon layer and a second passivation layer, which are sequentially arranged on the back side of the substrate;
[0009] A first passivation layer, which is disposed on the front side of the substrate;
[0010] The tunnel oxide layer includes a first region and a second region that are spaced apart, and the thickness of the first region is greater than the thickness of the second region.
[0011] In a technical solution of the above-mentioned TOPCon battery, the thickness of the second region is 0.8-1.6 nm.
[0012] In a second aspect, the present application provides a method for preparing a TOPCon battery, comprising:
[0013] Forming a tunneling oxide layer on the back side of the substrate, so that the tunneling oxide layer has a first region and a second region distributed at intervals, wherein the thickness of the first region is greater than the thickness of the second region;
[0014] forming a polysilicon layer on the tunnel oxide layer;
[0015] forming a first passivation layer on the front surface of the substrate;
[0016] A second passivation layer is formed on the back side of the substrate.
[0017] In a technical solution of the above-mentioned preparation method, the “forming a tunneling oxide layer on the back side of the substrate so that the tunneling oxide layer has a first region and a second region distributed at intervals” includes:
[0018] forming a patterned first tunnel oxide layer on the back side of the substrate;
[0019] A second tunneling oxide layer is formed, wherein the second tunneling oxide layer covers the first tunneling oxide layer and the exposed substrate.
[0020] In a technical solution of the above preparation method, the “forming a patterned first tunneling oxide layer on the back side of the substrate” includes:
[0021] Placing a mask plate on the back side of the substrate, wherein the mask plate has holes distributed at intervals;
[0022] depositing a first tunnel oxide layer;
[0023] The mask is removed to expose a portion of the substrate.
[0024] In a technical solution of the above preparation method, the “forming a patterned first tunneling oxide layer on the back side of the substrate” includes:
[0025] depositing a first tunnel oxide layer on the back side of the substrate;
[0026] Placing a mask plate on the first tunnel oxide layer, wherein the mask plate has holes distributed at intervals to expose a portion of the first tunnel oxide layer;
[0027] Etching the portion of the first tunnel oxide layer to expose a portion of the substrate;
[0028] Remove the mask.
[0029] In a technical solution of the above preparation method, the first tunneling oxide layer and the second tunneling oxide layer have the same thickness.
[0030] In a technical solution of the above preparation method, the “forming a second tunneling oxide layer” comprises:
[0031] The second tunnel oxide layer is deposited by a PECVD device, and N is introduced into the PECVD device during the deposition process. 2 A mixture of O gas and argon gas.
[0032] In one technical solution of the above preparation method, the N 2 In the mixed gas of O gas and argon gas, the argon gas accounts for 25%-38%.
[0033] In a technical solution of the above-mentioned preparation method, the “forming a tunneling oxide layer on the back side of the substrate so that the tunneling oxide layer has a first region and a second region distributed at intervals” includes:
[0034] forming a third tunnel oxide layer on the back side of the substrate;
[0035] A patterned fourth tunnel oxide layer is formed to expose a portion of the third tunnel oxide layer.
[0036] As mentioned above, in the case of adopting the above technical solution, in the preparation process of the TOPCon battery, the present application forms a tunneling oxide layer with different thicknesses. The thicker first area is used to ensure the passivation performance of the battery, which can not only ensure the sequential passage of electrons, but also effectively prevent the recombination of holes, thereby increasing the open circuit voltage. The thinner second area is used to reduce the contact resistance, thereby ensuring the contact performance of the battery. Therefore, by controlling the tunneling oxide layer to form a morphology of different thicknesses, the passivation ability and contact ability of the battery can be taken into account, thereby improving the photoelectric conversion efficiency.
[0037] Furthermore, in the process of depositing the second tunnel oxide layer based on the PECVD scheme of the present application, N 2 A mixture of O gas and argon gas in N 2 During the reaction of O and Si, the presence of argon will increase the proportion of oxygen atoms in the final second tunnel oxide layer. The increase in the oxygen content in the second tunnel oxide layer can improve its tolerance to temperature and reduce the possibility of the second tunnel oxide layer being broken down by high temperature. On the other hand, due to the presence of argon, a higher annealing temperature can be maintained during the deposition of the second tunnel oxide layer, thereby making the second tunnel oxide layer more compact. Similarly, the enhanced compactness of the second tunnel oxide layer can also improve the tolerance of the second tunnel oxide layer to temperature and reduce the possibility of the second tunnel oxide layer being broken down by high temperature. Therefore, N is introduced during the deposition of the second tunnel oxide layer. 2 The mixed gas of O gas and argon gas can improve the process window and ensure the molding quality while achieving the technical purpose of tunneling oxide layers of different thicknesses. BRIEF DESCRIPTION OF THE DRAWINGS
[0038] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, in which:
[0039] Figure 1 is a flow chart of the main steps of a method for preparing a TOPCon battery according to an embodiment of the present application;
[0040] Figure 2 is a detailed step flow chart of a method for preparing a TOPCon battery according to an embodiment of the present application;
[0041] Figure 3-Figure 9 According to this application Figure 2 A schematic cross-sectional view of a TOPCon cell of the embodiment shown during the preparation process;
[0042] Fig.10 is a detailed step flow chart of a method for preparing a TOPCon battery according to another embodiment of the present application;
[0043] Figure 11-Figure 15 According to this application Fig.10 A schematic cross-sectional view of the TOPCon cell of the illustrated embodiment during the preparation process.
[0044] In the figures, the reference numerals refer to the following:
[0045] 100, substrate; 110, mask plate; 200, boron-doped layer; 310, first tunneling oxide layer; 320, second tunneling oxide layer; 400, polysilicon layer; 500, first passivation layer; 600, second passivation layer. DETAILED DESCRIPTION
[0046] The preferred embodiments of the present application are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present application and are not used to limit the scope of protection of the present application. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.
[0047] It should be noted that in the description of this application, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the drawings. This is only for the convenience of description, and does not indicate or imply that the relevant devices or components must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on this application. In addition, the ordinal numbers "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.
[0048] In addition, it should be noted that in the description of this application, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0049] For TOPCon batteries, they usually include Si0x (tunneling oxide layer) and poly (polycrystalline silicon) structures. For traditional TOPCon batteries, the thickness of Si0x is consistent. When the thickness of Si0x is larger, although it has a higher passivation ability, it will affect the contact performance of the battery. When the thickness of Si0x is smaller, the contact performance is improved but the passivation ability of the battery will be reduced. Therefore, how to control the thickness of Si0x to simultaneously ensure the contact ability and passivation ability of the TOPCon battery has become an industry problem.
[0050] Moreover, when the thickness of Si0x is thin, it is easily broken down by high temperature during the process due to its tolerance to high temperature. Therefore, the disadvantage of its low process window also affects the molding quality of the battery.
[0051] Reference Figure 1 , is a flow chart of the main steps of a method for preparing a TOPCon battery according to an embodiment of the present application, which includes:
[0052] S101: forming a tunnel oxide layer on the back side of the substrate, so that the tunnel oxide layer has a first region and a second region which are spaced apart.
[0053] The thickness of the first region is greater than the thickness of the second region. Relatively speaking, the first region is a thicker region and the second region is a thinner region. In some embodiments, step S101 may include: forming a patterned first tunneling oxide layer on the back side of the substrate. Specifically, the first tunneling oxide layer includes a plurality of portions arranged at intervals, and the substrate is exposed between adjacent portions.
[0054] Then, a second tunnel oxide layer is formed on the substrate based on the first tunnel oxide layer, and the second tunnel oxide layer covers the first tunnel oxide layer and the exposed substrate.
[0055] By adopting the above method, the first tunnel oxide layer and the second tunnel oxide layer are combined to form the above tunnel oxide layer. Since the first tunnel oxide layer includes a plurality of independently distributed layers at intervals, and the second tunnel oxide layer is a continuous layer structure, the tunnel oxide layer finally formed naturally has interval-arranged regions of varying thicknesses, namely the first region and the second region mentioned above.
[0056] It should be noted that, although in the process of forming the tunneling oxide layer, the present application takes the example of first forming a patterned first tunneling oxide layer and then forming a continuous second tunneling oxide layer, but the actual application is not limited to this. For example, in some other implementations, a continuous third tunneling oxide layer can be first formed on the back of the substrate, and then a patterned fourth tunneling oxide layer is formed on the basis of the third tunneling oxide layer. The fourth tunneling oxide layer also includes a plurality of parts arranged at intervals, and the third tunneling oxide layer is exposed between adjacent parts. In this way, the third tunneling oxide layer and the fourth tunneling oxide layer can also be combined together to form a tunneling oxide layer of varying thicknesses to achieve the above technical purpose.
[0057] S102: forming a polysilicon layer on the tunnel oxide layer.
[0058] S103: forming a first passivation layer on the front surface of the substrate.
[0059] S104: forming a second passivation layer on the back side of the substrate.
[0060] As mentioned above, in the preparation process of the TOPCon battery, the present application forms a tunneling oxide layer with different thicknesses. The first area is used to ensure the passivation performance of the battery, which can not only ensure the sequential passage of electrons, but also effectively prevent the recombination of holes, thereby increasing the open circuit voltage. The second area is used to reduce the contact resistance, thereby ensuring the contact performance of the battery. Therefore, by controlling the tunneling oxide layer to form a morphology of different thicknesses, the passivation ability and contact ability of the battery can be taken into account, thereby improving the photoelectric conversion efficiency.
[0061] Reference Figure 2 , is a detailed step flow chart of a method for preparing a TOPCon battery according to an embodiment of the present application, and is combined with Figure 3-Figure 9 The cross-sectional schematic diagram of the TOPCon battery during the preparation process is described in the figure, which includes the following steps:
[0062] Reference Figure 3 First, step S1011 is performed: a mask plate 110 is placed on the back side of the substrate 100 .
[0063] The substrate 100 may be an N-type substrate with a thickness of 110-250 μm. Before step S1011, the steps of texturing and cleaning the substrate 100 are already included, and the substrate 100 is placed in a boron diffusion tube for boron diffusion, a boron doping layer 200 is formed on the front side of the substrate 100, and the BSG (borosilicate glass) and PN junction on the back side of the substrate 100 are removed by etching or the like.
[0064] In addition, if Figure 3 The mask plate 110 has holes distributed at intervals.
[0065] Then refer to Figure 4 , proceed to step S1012: depositing a first tunnel oxide layer 310 .
[0066] Depend on Figure 4 It can be seen that due to the existence of the mask plate 110 , the first tunnel oxide layer 310 is composed of a plurality of spaced-apart portions after being formed.
[0067] Then refer to Figure 5 , proceed to step S1013 : remove the mask plate 110 to expose a portion of the substrate 100 .
[0068] Then refer to Figure 6 , performing step S1014: forming a second tunnel oxide layer 320 so that the second tunnel oxide layer 320 covers the first tunnel oxide layer 310 and the exposed portion of the substrate 100 .
[0069] In step S1014, the second tunnel oxide layer 320 is deposited by PECVD. Therefore, after the first tunnel oxide layer 310 is deposited, the substrate 100 is placed in a PECVD device. In some embodiments of the present application, during the deposition of the second tunnel oxide layer 320 in step S1014, N is introduced into the PECVD device. 2 O gas and argon gas mixture, in this process, N 2 The O gas reacts with the substrate 100 as follows: 2N 2 O+Si=SiO 2 +2N 2 .
[0070] It can be understood that after the second tunnel oxide layer 320 is formed, the second tunnel oxide layer 320 and the first tunnel oxide layer 310 together constitute the tunnel oxide layer of the TOPCon battery, the area where the second tunnel oxide layer 320 overlaps with the first tunnel oxide layer 310 constitutes the above-mentioned first area, and the area where the second tunnel oxide layer 320 contacts the substrate 100 constitutes the above-mentioned second area. Therefore, in order to ensure the passivation ability and contact ability of the TOPCon battery at the same time, the thickness of the second tunnel oxide layer 320 is usually thinner. However, during the deposition of the second tunnel oxide layer 320, the ambient temperature is high. Under the influence of high temperature, when the thickness of the second tunnel oxide layer 320 is thinner, it is likely to be broken down by the high temperature, resulting in the phenomenon of partial failure of the second tunnel oxide layer 320 after the final formation.
[0071] In the present application, N is introduced into the process of depositing the second tunnel oxide layer 320. 2 A mixture of O gas and argon gas in N 2During the reaction of O and Si, the presence of argon will increase the proportion of oxygen atoms in the final second tunnel oxide layer 320. The increase in the oxygen content in the second tunnel oxide layer 320 can improve its tolerance to temperature and reduce the possibility of the second tunnel oxide layer 320 being broken down by high temperature.
[0072] On the other hand, due to the presence of argon gas, a relatively high annealing temperature can be maintained during the deposition of the second tunnel oxide layer 320, thereby making the second tunnel oxide layer 320 more compact. Similarly, the enhanced compactness of the second tunnel oxide layer 320 can also improve the temperature tolerance of the second tunnel oxide layer 320 and reduce the possibility of the second tunnel oxide layer 320 being broken down by high temperature.
[0073] It can be seen that the second tunnel oxide layer 320 is deposited by using the PECVD scheme, and the N 2 The mixed gas of O gas and argon gas can improve the process window while achieving the technical purpose of tunneling oxide layers of different thicknesses.
[0074] As shown in Table 1, the inventors conducted experiments and found that during step S1014, under the condition that the annealing temperature is 950°C and the argon gas accounts for 1.3% of the N 2 The ratio of the mixed gas of O gas and argon gas is different for each working condition with different parameters, and tests are performed respectively (wherein, Eta: conversion efficiency, Voc: open circuit voltage, Jsc: short circuit current, FF: fill factor). Argon ratio (%) Voc(mV) <![CDATA[Jsc(mA / cm 2 )]]> FF(%) Eta(%) 28 733 40.8 83.8 25.06 16 730 40.8 83.5 24.86 37.5 731 40.8 83.4 24.9 44 719 40.8 79.4 23.2 Table 1
[0075] It can be seen from the table that when the proportion of argon is about 28%, the open circuit voltage is the largest, the filling factor is the largest (the filling factor is the ratio of the maximum output power of the battery to the product of the open circuit voltage and the short circuit current. The larger the filling factor, the higher the photoelectric conversion efficiency of the battery), and the conversion efficiency is the highest. According to research and testing by the inventors, when the proportion of argon is in the range of 25%-38%, the TOPCon battery has a relatively high filling factor and conversion efficiency. Therefore, in step S1014, the proportion of argon can be controlled within the above range, thereby improving the conversion efficiency of the TOPCon battery.
[0076] In some embodiments of the present application, in step S1012 and step S1014, the thickness of the first tunnel oxide layer 310 and the second tunnel oxide layer 320 formed are the same. In this way, the same process parameters can be used in the two process steps, thereby simplifying the complexity of the process.
[0077] It should also be noted that in the above step S1014 of the present application, since N 2The second tunnel oxide layer 320 is a mixture of argon and oxygen gas, and the content of oxygen atoms and its compactness in the second tunnel oxide layer 320 are increased by adjusting the proportion of argon gas, thereby improving the temperature tolerance. Therefore, according to actual needs, in some implementations, the thickness of the second tunnel oxide layer 320 can be further reduced to improve the contact ability of the TOPCon battery. According to the inventor's experiment, the annealing temperature during the deposition of the second tunnel oxide layer 320 is controlled to be maintained in the range of 900°C-980°C, so that the thickness of the second tunnel oxide layer 320 can be controlled in the range of 0.8-1.6nm.
[0078] Then refer to Figure 7 , proceed to step S102 : forming a polysilicon layer 400 on the second tunnel oxide layer 320 .
[0079] The polysilicon layer 400 may be a multi-layer structure, for example, doped with one or more of P, B, Ga, C, O, and N, and the thickness of the polysilicon layer 400 is 60-300 nm.
[0080] At the same time, after step S1021, PSG (phosphosilicate glass) and poly wrap plating on the front side of the substrate 100 are removed.
[0081] Then refer to Figure 8 , proceed to step S103 : forming a first passivation layer 500 on the front side of the substrate 100 .
[0082] In step S103, the first passivation layer 500 may be AlOx and SiNx, that is, a mixture of aluminum oxide and silicon nitride. For example, when step S103 is performed, ALD (atomic layer deposition) may be used to deposit the AlOx layer first, and then PECVD may be used to deposit the SiNx layer.
[0083] Then refer to Fig. 9 , proceed to step S104 : forming a second passivation layer 600 on the polysilicon layer 400 on the back side of the substrate 100 .
[0084] The second passivation layer 600 may be a SiNx layer or the like, and similarly, it may be deposited by PECVD.
[0085] Finally, the front electrode and the back electrode can be prepared by slurry printing, which is a well-known technology in the art and will not be elaborated in detail in this application.
[0086] Reference Fig.10 , is another detailed step flow chart of the method for preparing a TOPCon battery according to an embodiment of the present application, and is combined with Figure 11-Figure 15 The cross-sectional diagram of the TOPCon battery during the preparation process is described in the following. It should be noted that this method is different from Figure 2 The difference between the two methods is only the formation of the tunnel oxide layer, that is, the two methods are basically the same in steps S102 to S104, so the description is mainly based on the above difference, which includes the following steps:
[0087] Reference Fig.11 First, step S1015 is performed: a first tunnel oxide layer 310 is deposited on the back side of the substrate 100 .
[0088] It should be noted that in step S1015, the first tunnel oxide layer 310 is a continuous layer structure, which covers the back side of the substrate 100. Similarly, before step S1015, the steps of texturing and cleaning the substrate 100 are already included, and the substrate 100 is placed in a boron diffusion tube for boron diffusion, a boron doping layer 200 is formed on the front side of the substrate 100, and the BSG (borosilicate glass) and PN junction on the back side of the substrate 100 are removed by etching or the like.
[0089] Then refer to Fig.12 , proceed to step S1016 : placing a mask plate 110 on the first tunnel oxide layer 310 .
[0090] The mask plate 110 has holes distributed at intervals, so that the hole areas can expose the first tunnel oxide layer 310 .
[0091] Then refer to Fig.13 , performing step S1017: etching a portion of the first tunnel oxide layer 310 to expose a portion of the substrate 100 .
[0092] Then refer to Fig.14 , proceed to step S1018: remove the mask plate 110.
[0093] At this point, the first tunnel oxide layer 310 finally appears as a plurality of portions arranged at intervals.
[0094] Then refer to Fig.15 , based on the first tunnel oxide layer 310 , step S1019 is performed: forming a second tunnel oxide layer 320 .
[0095] The second tunnel oxide layer 320 covers the first tunnel oxide layer 310 and the exposed substrate 100. After the second tunnel oxide layer 320 is formed, the second tunnel oxide layer 320 and the first tunnel oxide layer 310 together constitute the tunnel oxide layer of the TOPCon cell. The area where the second tunnel oxide layer 320 overlaps with the first tunnel oxide layer 310 constitutes the above-mentioned first area, and the area where the second tunnel oxide layer 320 contacts the substrate 100 constitutes the above-mentioned second area. It can be seen that the above method can also achieve the technical purpose of different thickness of the tunnel oxide layer.
[0096] Similarly, during step S1019, N may be introduced into the PECVD device. 2 A mixed gas of O gas and argon gas is used to improve the temperature tolerance of the second tunnel oxide layer, which will not be described in detail in this application.
[0097] Of course, the above methods are only some exemplary methods provided by the present application, and they do not constitute a limitation to the present application. For example, in some other implementations, in order to form a tunneling oxide layer of varying thickness, a thicker tunneling oxide layer may be first deposited on the back side of the substrate 100, and then different parts of the surface of the tunneling oxide layer may be removed at intervals by laser cutting to form a first region and a second region arranged at intervals.
[0098] The present application also discloses a TOPCon cell, which includes a substrate, a tunneling oxide layer, a polysilicon layer, a first passivation layer and a second passivation layer.
[0099] The substrate may be an N-type substrate, the first passivation layer is arranged on the front side of the substrate, and the tunneling oxide layer, the polysilicon layer and the second passivation layer are arranged on the back side of the substrate in sequence. The tunneling oxide layer includes a first region and a second region that are spaced apart, the thickness of the first region is greater than the thickness of the second region, and the tunneling oxide layer may be prepared by the preparation method in any of the above embodiments. For example, in one implementation, the tunneling oxide layer includes the first tunneling oxide layer and the second tunneling oxide layer in the above method embodiment, thereby forming the above thicker first region and the thinner second region.
[0100] Of course, the TOPCon battery also includes metal electrodes disposed on the first passivation layer and the second passivation layer, respectively. In one implementation of the present application, the second region of the tunnel oxide layer corresponds to the location of the metal electrode, thereby further improving the contact performance of the battery.
[0101] Optionally, the thickness of the second region of the tunnel oxide layer is 0.8-1.6 nm.
[0102] It should be noted that in actual applications, the positions and relative sizes of the first region and the second region can be adjusted according to actual needs. For example, the width of the second region can be made smaller than the width of the first region, and the metal electrode can correspond to the second region. In this way, the passivation performance of the battery can be improved and the contact performance requirements can be met, thereby further improving the photoelectric conversion efficiency.
[0103] So far, the technical solutions of the present application have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present application.
Claims
1. A TOPCon battery, characterized in that: include: a substrate comprising a front surface and a back surface opposite to the front surface; A tunneling oxide layer, a polysilicon layer and a second passivation layer, which are sequentially arranged on the back side of the substrate; A first passivation layer, which is disposed on the front side of the substrate; The tunnel oxide layer includes a first region and a second region that are spaced apart, and the thickness of the first region is greater than the thickness of the second region.
2. The TOPCon battery according to claim 1, characterized in that The thickness of the second region is 0.8-1.6 nm.
3. A method for preparing a TOPCon battery, characterized in that: include: Forming a tunneling oxide layer on the back side of the substrate, so that the tunneling oxide layer has a first region and a second region distributed at intervals, wherein the thickness of the first region is greater than the thickness of the second region; forming a polysilicon layer on the tunnel oxide layer; forming a first passivation layer on the front surface of the substrate; A second passivation layer is formed on the back side of the substrate.
4. The method according to claim 3, characterized in that The step of forming a tunnel oxide layer on the back side of the substrate so that the tunnel oxide layer has a first region and a second region that are spaced apart comprises: forming a patterned first tunnel oxide layer on the back side of the substrate; A second tunneling oxide layer is formed, wherein the second tunneling oxide layer covers the first tunneling oxide layer and the exposed substrate.
5. The method according to claim 4, characterized in that The “forming a patterned first tunneling oxide layer on the back side of the substrate” comprises: Placing a mask plate on the back side of the substrate, wherein the mask plate has holes distributed at intervals; depositing a first tunnel oxide layer; The mask is removed to expose a portion of the substrate.
6. The method according to claim 4, characterized in that The “forming a patterned first tunneling oxide layer on the back side of the substrate” comprises: depositing a first tunnel oxide layer on the back side of the substrate; Placing a mask plate on the first tunnel oxide layer, wherein the mask plate has holes distributed at intervals to expose a portion of the first tunnel oxide layer; Etching the portion of the first tunnel oxide layer to expose a portion of the substrate; Remove the mask.
7. The method according to claim 4, characterized in that The first tunnel oxide layer and the second tunnel oxide layer have the same thickness.
8. The method according to any one of claims 4 to 7, characterized in that The forming of the second tunneling oxide layer comprises: The second tunnel oxide layer is deposited by a PECVD device, and a mixed gas of N2O gas and argon gas is introduced into the PECVD device during the deposition process.
9. The method according to claim 8, characterized in that In the mixed gas of the N2O gas and the argon gas, the argon gas accounts for 25%-38%.
10. The method according to claim 3, characterized in that: The step of forming a tunnel oxide layer on the back side of the substrate so that the tunnel oxide layer has a first region and a second region that are spaced apart comprises: forming a third tunnel oxide layer on the back side of the substrate; A patterned fourth tunnel oxide layer is formed to expose a portion of the third tunnel oxide layer.