Solar cell manufacturing method and solar cell

Abstract

The present application provides a method for manufacturing a solar cell, comprising: manufacturing a boron diffusion layer on the front side of a silicon substrate, manufacturing a front aluminum oxide layer on the boron diffusion layer by a plasma enhanced atomic layer deposition process, wherein the number of cycles of the plasma enhanced atomic layer deposition process is n, wherein n is less than or equal to 80, wherein the manufacturing of the front aluminum oxide layer comprises: manufacturing a first aluminum oxide layer on the boron diffusion layer, wherein the deposition power during the manufacturing process of the first aluminum oxide layer is greater than or equal to 7500w and less than 10000w, wherein the number of cycles is less than or equal to 35%n, and manufacturing a second aluminum oxide layer on the first aluminum oxide layer, wherein the deposition power during the manufacturing process of the second aluminum oxide layer is greater than or equal to 10000w and less than 15000w. The method for manufacturing a solar cell improves the quality of the solar cell and improves the efficiency of the solar cell.

Description

Technical Field

[0001] The present application belongs to the technical field of photovoltaic solar cells, and more specifically, relates to a method for manufacturing a solar cell and a solar cell. Background Art

[0002] The conventional methods for preparing photovoltaic solar cells are generally atomic layer deposition (ALD) and plasma enhanced atomic layer deposition (PEALD). Among them, the ALD heat source flux is large, and it is difficult to achieve a single layer deposition of the passivation layer; PEALD can control the number of cycles to achieve the deposition of a preset thickness of the passivation layer.

[0003] TOPCon (Tunnel Oxide Passivated Contact) is a tunnel oxide passivated contact solar cell technology based on the principle of selective carriers. Its cell structure is an N-type silicon substrate cell. An ultra-thin layer of silicon oxide is prepared on the back of the cell, and then a thin layer of doped silicon is deposited. The two together form a passivated contact structure, which effectively reduces surface recombination and metal contact recombination. TOPCon has attracted more and more attention from the market due to its excellent efficiency and compatibility, and has become the entry point for the industrialization of N-type high-efficiency cells.

[0004] When the N-type TOPCon cell is passivated on the front side by PEALD, it needs to be optimized in combination with the boron diffusion surface, which can easily damage the boron diffusion surface and lead to reduced efficiency of the TOPCon cell. Summary of the invention

[0005] The purpose of the present application is to provide a solar cell manufacturing method and a solar cell to improve the passivation effect during the solar cell manufacturing process and enhance the cell efficiency.

[0006] To achieve the above objectives, the technical solution adopted by the present application is: In a first aspect, the present application provides a method for manufacturing a solar cell, comprising:

[0007] forming a boron diffusion layer on the front side of the silicon substrate;

[0008] A front aluminum oxide layer is formed on the boron diffusion layer by a plasma enhanced atomic layer deposition process, the number of cycles of the plasma enhanced atomic layer deposition process is n, and n is less than or equal to 80. The forming of the front aluminum oxide layer includes:

[0009] A first aluminum oxide layer is formed on the boron diffusion layer, wherein a deposition power during the formation of the first aluminum oxide layer is greater than or equal to 7500W and less than 10000W, and the number of cycles is less than or equal to 35%n;

[0010] A second aluminum oxide layer is fabricated on the first aluminum oxide layer, wherein a deposition power during the fabrication of the second aluminum oxide layer is greater than or equal to 10,000 W and less than 15,000 W.

[0011] In one embodiment, the thickness of the first aluminum oxide layer is greater than or equal to 0.3 nm and less than or equal to 0.6 nm, and the thickness of the second aluminum oxide layer is greater than or equal to 2 nm and less than or equal to 4 nm.

[0012] In one embodiment, the deposition power during the manufacturing process of the first aluminum oxide layer is greater than or equal to 9000W and less than or equal to 9600W, and the deposition power during the manufacturing process of the second aluminum oxide layer is greater than or equal to 10000W and less than or equal to 12000W.

[0013] In one embodiment, after forming the second aluminum oxide layer on the first aluminum oxide layer, the method further includes: forming a silicon nitride layer or a silicon oxynitride layer on the second aluminum oxide layer.

[0014] In one embodiment, forming a silicon nitride layer or a silicon oxynitride layer on the second aluminum oxide layer includes:

[0015] The silicon nitride layer or the silicon oxynitride layer is deposited on the second aluminum oxide layer by using a plasma enhanced chemical vapor deposition process.

[0016] In one embodiment, depositing the silicon nitride layer or the silicon oxynitride layer on the second aluminum oxide layer using a plasma enhanced chemical vapor deposition process comprises:

[0017] A first silicon nitride layer or a first silicon nitride oxide layer is deposited on the second aluminum oxide layer, wherein a deposition temperature of the first silicon nitride layer or the first silicon nitride oxide layer is greater than or equal to 460° C. and less than 500° C.

[0018] In one embodiment, a second silicon nitride layer or a second silicon nitride oxide layer is deposited on the first silicon nitride layer or the first silicon nitride oxide layer, wherein a deposition temperature of the second silicon nitride layer or the second silicon nitride oxide layer is greater than or equal to 500° C. and less than or equal to 560° C.

[0019] In one embodiment, after forming a boron diffusion layer on the front side of the silicon substrate, the method further comprises:

[0020] forming a tunneling oxide layer and a doped polysilicon layer in sequence on the back side of the silicon substrate;

[0021] A plasma enhanced atomic layer deposition process is adopted to sequentially deposit a back aluminum oxide layer and a silicon nitride layer on the doped polysilicon layer.

[0022] In one embodiment, the front aluminum oxide layer is formed on the boron diffusion layer and the back aluminum oxide layer is formed on the doped polysilicon layer at the same time.

[0023] A second aspect of the present application provides a solar cell, which is manufactured using the solar cell manufacturing method as described above.

[0024] The solar cell manufacturing method provided in the present application includes: manufacturing a boron diffusion layer on the front side of a silicon substrate, manufacturing a front aluminum oxide layer on the boron diffusion layer, and manufacturing the front aluminum oxide layer on the boron diffusion layer by using a plasma enhanced atomic layer deposition process, wherein the number of cycles of the plasma enhanced atomic layer deposition process is less than or equal to 80. The manufacturing of the front aluminum oxide layer includes: depositing a first aluminum oxide layer on the boron diffusion layer by using a plasma enhanced atomic layer deposition method, wherein the deposition power of the first aluminum oxide layer is greater than or equal to 7500w and less than 10000w, and the number of cycles is less than or equal to 35%n; manufacturing a second aluminum oxide layer on the first aluminum oxide layer by using a plasma enhanced atomic layer deposition method, wherein the deposition power of the second aluminum oxide layer is greater than or equal to 10000w and less than 15000w. The solar cell manufacturing method manufactures the first aluminum oxide layer at low power and then manufactures the second aluminum oxide layer at high power. Since low power is used when manufacturing the first aluminum oxide layer, damage to the boron diffusion layer is reduced. The deposition power of the second aluminum oxide layer is high power, and the deposition speed is fast and the density is good, thereby improving the quality of the solar cell and the efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 A flow chart of a method for manufacturing a solar cell provided in an embodiment of the present application;

[0027] Figure 2 A flow chart of a method for manufacturing a solar cell provided in an embodiment of the present application;

[0028] Figure 3 A flow chart of a method for manufacturing a solar cell provided in an embodiment of the present application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] In the description of the present application, it should be understood that the terms "including" and "having" and any variations thereof used herein are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0031] In addition, in the present application, unless otherwise clearly stipulated and limited, the terms "connect", "connected", "fixed", "installed", etc. should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in this application according to the specific circumstances.

[0032] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. It should be understood that in the description of this application, unless otherwise specified, the meaning of "plurality" is two or more.

[0033] TOPCon (Tunnel Oxide Passivated Contact) is a tunnel oxide passivated contact solar cell technology based on the principle of selective carriers. Its cell structure is an N-type silicon substrate cell. An ultra-thin layer of silicon oxide is prepared on the back of the cell, and then a thin layer of doped silicon is deposited. The two together form a passivated contact structure, which effectively reduces surface recombination and metal contact recombination. TOPCon has the advantages of long minority carrier lifetime and no photodegradation effect, and is increasingly attracting market attention.

[0034] Some terms in this application are explained below to facilitate understanding by those skilled in the art.

[0035] Atomic layer deposition (ALD): It is a method that can coat a substance layer by layer on the surface of a substrate in the form of a single atomic film. The deposited film is formed by alternately passing gaseous precursor pulses into the reactor and chemically adsorbing and reacting on the deposition substrate. When the precursors reach the surface of the deposition substrate, they will chemically adsorb on its surface and undergo surface reactions. The atomic layer deposition reactor needs to be cleaned with an inert gas between precursor pulses. It can be seen that whether the deposition reaction precursor substance can chemically adsorb on the surface of the deposited material is the key to achieving atomic layer deposition. The surface adsorption characteristics of gaseous substances on the substrate material show that any gaseous substance can be physically adsorbed on the surface of the material, but the chemical adsorption on the surface of the material must have a certain activation energy. Therefore, whether atomic layer deposition can be achieved and whether the appropriate reaction precursor substance can be selected is very important.

[0036] A basic atomic layer deposition cycle includes four steps: intake → exhaust → discharge pulse on and off → exhaust. The deposition cycle is repeated until the desired film thickness is obtained. It is a tool for making nanostructures and thus forming nanodevices. The specific process of a single time is as follows: the intake reaction source gas and inert gas enter the tube. After the exhaust is completed, the pressure is extremely low and close to vacuum. The gas adsorbed on the surface of the battery cell is extremely thin. The reaction source gas is ionized under the pulse condition, and then the deposition is close to the atomic layer thickness on the surface of the substrate. The gas in the tube and its reaction intermediates are extracted by exhaust, so that the conditions are basically the same each time. The set thickness requirement is achieved through multiple cycles.

[0037] Plasma enhanced atomic layer deposition (PEALD): It is a combination of plasma assisted and atomic layer deposition. It dissociates monomers or reactive gases through plasma to provide active groups required for the reaction.

[0038] Plasma enhanced chemical vapor deposition (PECVD): It is a method of exciting gas in chemical vapor deposition to produce low-temperature plasma, enhance the chemical activity of the reactant, and thus perform epitaxy. This method can form a solid film at a relatively low temperature. For example, in a reaction chamber, the substrate material is placed on the cathode, and the reaction gas is introduced to a relatively low pressure (1-600 Pa). The substrate is kept at a certain temperature, and a glow discharge is generated in some way. The gas near the substrate surface is ionized, the reaction gas is activated, and cathode sputtering occurs on the substrate surface, thereby increasing the surface activity. There are not only the usual thermochemical reactions on the surface, but also complex plasma chemical reactions. The deposited film is formed under the combined action of these two chemical reactions.

[0039] The solar cell manufacturing method and the solar cell provided by the invention are described in detail below in conjunction with specific embodiments.

[0040] This application takes the production of N-type TOPCon cells as an example for explanation. The front structure of existing N-type TOPCon cells is generally: from the inside to the outside, there are semiconductor substrate, boron diffusion layer, and front passivation layer, wherein the front passivation layer is generally an aluminum oxide layer and a silicon nitride layer, and the aluminum oxide layer is mostly a single-layer structure. The inventors found that when the aluminum oxide layer of the front passivation layer is prepared by the PEALD process, trimethylaluminum is generally used as a precursor, oxygen is used as a reactant, the reaction temperature is 20-120°C, and radio frequency plasma is assisted, and the growth rate of aluminum oxide is 0.1-0.2nm / cycle. The inventors have discovered that in the existing aluminum oxide production process, when the process temperature is low, the precursor gas has poor reactivity and atom migration rate is low, TMA and oxygen-containing active groups are easily cooled by the silicon wafer, and the nucleation rate is slow or even unable to nucleate, resulting in a rough surface, poor density, and poor field passivation effect of the aluminum oxide film. At lower temperatures, there may even be incomplete activation or condensation of the precursor. After appropriately increasing the process temperature, the atomic mobility is improved, and the atoms can migrate to the appropriate lattice position for nucleation, which is conducive to the escape of reaction by-products from the silicon wafer surface. The corresponding aluminum oxide film is smooth, dense, and has a good field passivation effect. As the process temperature increases, the energy carried by the particles bombarding the silicon wafer surface gradually increases, causing the already formed aluminum oxide to fall off under the bombardment of plasma, aggravating the damage to the silicon wafer surface, increasing the recombination of the silicon wafer surface, and reducing the effective minority carrier lifetime. Under the same process conditions, only the RF power is changed. As the RF power increases from small to large, the corresponding effective minority carrier lifetime of the silicon wafer shows a trend of first increasing and then decreasing. This is because as the RF power increases, the energy carried by the plasma increases, providing sufficient activation energy for the reaction, and the collision of gas phase molecules further promotes the decomposition, combination, excitation and ionization of the gas molecules, producing more highly active film-forming groups, which increases the thickness and density of the deposited aluminum oxide film, thereby enhancing the field passivation effect of the aluminum oxide film and increasing the minority carrier lifetime of the silicon wafer. However, excessive RF power will cause serious RF damage to the silicon wafer due to the excessive energy carried by the film-forming groups, and the damage caused by the plasma bombarding the silicon wafer surface will increase, resulting in increased surface recombination and a decrease in the effective minority carrier lifetime.

[0041] In order to increase the effective minority carrier lifetime of silicon wafers and improve the efficiency of solar cells, this embodiment provides a method for manufacturing solar cells. Figure 1 For a flow chart of the solar cell manufacturing method provided in the embodiment of the present application, please refer to Figure 1 The solar cell manufacturing method of this embodiment includes:

[0042] S101, forming a boron diffusion layer on the front side of the silicon substrate;

[0043] Specifically, this embodiment takes the production of TOPCon cells as an example to introduce the process, in which the silicon substrate is textured and the front side is expanded with boron to form a boron diffusion layer. The specific process is as follows: the texture process is to place the N-type original silicon wafer into a texture tank, the KOH volume concentration in the tank is 1%-20%, the temperature is 40-80°C, and the additive is 2-20L, followed by water washing, acid washing (HF volume concentration is 1%-30%), water washing, slow pulling, and drying, and the drying temperature is 80-105°C. The textured silicon wafer is placed in a boron expansion tube, the source temperature is 700-900°C, the time is 20-2000s, the junction temperature is 900-1200°C, and the time is 100-5000s.

[0044] A plasma enhanced atomic layer deposition process is used to form a front aluminum oxide layer on the boron diffusion layer. The number of cycles of the plasma enhanced atomic layer deposition process is n, and n is less than or equal to 80. Exemplarily, the number of cycles is 30, 45, 80, etc., and is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable.

[0045] In the process of making aluminum oxide by PEALD process, each cycle of this embodiment includes two half reactions. At the beginning, water vapor in the air is adsorbed by the surface of the silicon wafer to form hydrocarbon groups on the surface of the silicon wafer. After the silicon wafer is placed in the reaction furnace tube, the TMA precursor gas pulse is passed into the reaction chamber, and TMA reacts with the adsorbed hydrocarbon groups until the surface is completely passivated. The aluminum atom methyl group covers the entire surface of the silicon wafer, and the remaining TMA molecules and the methane generated by the reaction are purged out of the furnace tube. In the next step, water vapor enters the furnace tube. Under radio frequency excitation, oxygen free radicals react with the suspended methyl groups to form Al-O bonds and new surface hydrocarbon groups. The remaining reaction products are purged out of the furnace tube, completing a reaction cycle to generate a single atomic layer of aluminum oxide. Repeat the above process to reach an aluminum oxide layer of preset thickness. The thickness of the aluminum oxide film is determined by the production cycle, and the thickness of the aluminum oxide film is generally tested using an ellipsometer. Since the front of the TOPCon battery is usually passivated with an aluminum oxide and silicon nitride laminate film, the thickness of the aluminum oxide film is appropriately increased, the corresponding field passivation effect is enhanced, the passivation effect of the silicon wafer surface is enhanced, and the effective minority carrier lifetime is increased. The hydrogen passivation mechanism of silicon nitride is: during the preparation of the silicon nitride film layer, a large number of hydrogen atoms pass through the dangling bonds on the saturated grain boundaries, significantly weakening the recombination center, reducing the surface state density, and passivating the surface and body of the silicon wafer. When the thickness of the aluminum oxide film layer is too thick, the hydrogen in the silicon nitride film is blocked by it, resulting in the obstruction of hydrogen passivation, which will further lead to the deterioration of the overall passivation of the silicon wafer surface, resulting in a decrease in the effective minority carrier lifetime. The number of cycles of the plasma enhanced atomic layer deposition process of this embodiment is less than or equal to 80, and the thickness of the aluminum oxide layer produced is generally less than 10nm.

[0046] The manufacturing of the front aluminum oxide layer comprises:

[0047] S102, forming a first aluminum oxide layer on the boron diffusion layer, wherein a deposition power during the formation of the first aluminum oxide layer is greater than or equal to 7500W and less than 10000W, and the number of cycles is less than or equal to 35%n;

[0048] Specifically, the first aluminum oxide layer is made by the PEALD process. The deposition power used in the process of making the first aluminum oxide layer of this embodiment is low power, and the deposition power is greater than or equal to 7500w and less than 10000w. For example, the deposition power is 7500w, 8000w, 9500w, and 9800w, which are not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable. The PEALD process conditions are: the temperature is 200-250°C, the process is: TMA, 4-8s, purge 7-10s, H2O, 4-8s, purge 7-10s, the number of cycles is less than or equal to 35%n, and the processing method of each cycle is to first introduce TMA for 4-8s, purge 7-10s, and then introduce water vapor for 4-8s, purge 7-10s, wherein TMA is Al(CH), and TMA and water vapor form an aluminum oxide film together. In this embodiment, the number of cycles of the first aluminum oxide layer deposited at low power is greater than 3 and less than or equal to 35%n, which avoids damage to the boron diffusion layer caused by excessive RF power. The first aluminum oxide deposited at low power has low efficiency, and the number of cycles of low power deposition is less than or equal to 35%n, which can ensure the production efficiency of the front aluminum oxide layer. n represents the total number of cycles for making the first aluminum oxide layer and the second aluminum oxide layer. When 35%n is a non-integer, it is rounded to the nearest integer. For example, when n=40, the number of cycles for making the first aluminum oxide layer is less than or equal to 14, which can be 14, 8 or 7.

[0049] In this embodiment, the deposition power when forming the first aluminum oxide layer on the boron diffusion layer is low power, which avoids excessively high RF power. Because the film-forming groups carry too high energy, the damage to the boron diffusion layer caused by plasma bombarding the silicon wafer surface is increased, and the effective minority carrier lifetime is reduced, thereby improving the passivation quality of the solar cell and improving the battery efficiency.

[0050] S103. Fabricate a second aluminum oxide layer on the first aluminum oxide layer, wherein a deposition power during the fabrication of the second aluminum oxide layer is greater than or equal to 10,000 W and less than 15,000 W.

[0051] Specifically, the deposition power used in the process of making the second aluminum oxide layer of this embodiment is high power, and the deposition power is greater than or equal to 10000w and less than 15000w. For example, the deposition power is 10000w, 11000w, 12000w, and 15000w, and is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable. The PEALD process conditions are: the temperature is 200-250℃, the process is: TMA, 4-8s, purge 7-10s, H2O, 4-8s, purge 7-10s, and the processing method of each cycle is to first introduce TMA for 4-8s, purge 7-10s, and then introduce water vapor for 4-8s and purge 7-10s, wherein TMA is Al(CH), and TMA and water vapor together generate aluminum oxide film. The number of cycles for making the second aluminum oxide layer in this embodiment is n-35%n. When 35%n is a non-integer, it is rounded to the nearest integer. Exemplarily, the deposition power during the production of the first aluminum oxide layer is 11000w. When n=40, the number of cycles for producing the first aluminum oxide layer is 8, and the number of cycles for producing the first aluminum oxide layer is 32. The number of cycles for the second aluminum oxide layer is greater than the number of cycles for the first aluminum oxide layer, which can improve the production efficiency of the front aluminum oxide layer. In this embodiment, the deposition power for producing the second aluminum oxide layer is high power, and the aluminum oxide layer has a fast deposition speed and good density.

[0052] The solar cell manufacturing method provided in this embodiment includes: manufacturing a boron diffusion layer on the front side of a silicon substrate, manufacturing a front aluminum oxide layer on the boron diffusion layer, and manufacturing the front aluminum oxide layer on the boron diffusion layer by using a plasma enhanced atomic layer deposition process, wherein the number of cycles of the plasma enhanced atomic layer deposition process is less than or equal to 80. Manufacturing the front aluminum oxide layer includes: depositing a first aluminum oxide layer on the boron diffusion layer by using a plasma enhanced atomic layer deposition method, wherein the deposition power of the first aluminum oxide layer is greater than or equal to 7500w and less than 10000w, and the number of cycles is less than or equal to 35%n; manufacturing a second aluminum oxide layer on the first aluminum oxide layer by using a plasma enhanced atomic layer deposition method, wherein the deposition power of the second aluminum oxide layer is greater than or equal to 10000w and less than 15000w. The solar cell manufacturing method manufactures the first aluminum oxide layer at low power and then manufactures the second aluminum oxide layer at high power. Since low power is used when manufacturing the first aluminum oxide layer, damage to the boron diffusion layer is reduced. The deposition power of the second aluminum oxide layer is high power, and the deposition speed is fast and the density is good, thereby improving the quality of the TOPCon battery and the efficiency of the TOPCon battery.

[0053] In a specific embodiment, the thickness of the first aluminum oxide layer is greater than or equal to 0.3nm and less than or equal to 0.6nm, and the thickness of the second aluminum oxide layer is greater than or equal to 2nm and less than or equal to 4nm. The first aluminum oxide layer of this embodiment is made with low power, and the thickness of the first aluminum oxide layer is greater than or equal to 0.3nm and less than or equal to 0.6nm. For example, the thickness of the first aluminum oxide layer is 0.3nm, 0.4nm, 0.5nm, 0.6nm, and is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable. The thickness of the first aluminum oxide layer made with low power is thinner, the number of cycles is small, and the preparation efficiency is high. The second aluminum oxide layer is made with relatively high power, and the thickness of the second aluminum oxide layer is 2nm-4nm. For example, the thickness of the second aluminum oxide layer is 2nm, 3nm, 4nm, and is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable. The thickness of the front aluminum oxide film layer of this embodiment is appropriate, the overall passivation effect of the silicon wafer surface is good, and the effective minority carrier lifetime is improved.

[0054] In a specific embodiment, the deposition power during the production of the first aluminum oxide layer is greater than or equal to 9000W and less than or equal to 9600W. For example, the deposition power during the production of the first aluminum oxide layer is 9500, which is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable. The deposition power during the production of the second aluminum oxide layer is greater than or equal to 10000W and less than or equal to 12000W. For example, the deposition power during the production of the second aluminum oxide layer is 11000, which is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable. The deposition power when the first aluminum oxide layer is produced in this embodiment is low power, which avoids excessive RF power because the film-forming groups carry too much energy, and the plasma bombardment of the silicon wafer surface causes increased damage to the boron diffusion layer, and reduces the effective minority carrier lifetime, thereby improving the passivation quality of the solar cell and improving the battery efficiency. The second aluminum oxide layer is produced with relatively high power, and the second aluminum oxide layer has a fast deposition rate and good film density, which is beneficial to the hydrogen passivation of silicon nitride in the later stage, and improves the passivation effect of the solar cell.

[0055] In this embodiment, a silicon nitride layer is superimposed on the front aluminum oxide layer for passivation, wherein the deposition power during the production of the first aluminum oxide layer is 9500w, and the number of cycles is 5, and the deposition power during the production of the second aluminum oxide layer is 11000w, and the number of cycles is 32. The following table shows the test data of the TOPCon battery produced by the production method of this embodiment and the TOPCon battery produced by the existing production method.

[0056]

[0057]

[0058] Table 1 Test data of embodiments and comparative examples

[0059] The front aluminum oxide layer in the comparative examples in Tables 1 and 2 was produced by 37 cycles of deposition power of 9500W, and the front aluminum oxide layer in the embodiment was produced by 5 cycles of deposition power of 9500W + 32 cycles of deposition power of 9500W.

[0060] It can be seen from Table 1 that, compared with the TOPCon cell manufactured by the conventional manufacturing method of the comparative example, the minority carrier lifetime of the TOPCon cell manufactured by the solar cell manufacturing method of this embodiment is greatly improved.

[0061]

[0062] Table 2 Test data of embodiments and comparative examples

[0063] It can be seen from Table 2 that, compared with the TOPCon cell manufactured by the conventional manufacturing method of the comparative example, the conversion efficiency of the TOPCon cell manufactured by the solar cell manufacturing method of this embodiment is significantly improved.

[0064] Figure 2 For a flow chart of the solar cell manufacturing method provided in the embodiment of the present application, please refer to Figure 2 The solar cell manufacturing method of the embodiment of the present invention comprises the following steps:

[0065] S201, forming a boron diffusion layer on the front side of the silicon substrate;

[0066] S202, forming a first aluminum oxide layer on the boron diffusion layer, wherein a deposition power during the formation of the first aluminum oxide layer is greater than or equal to 7500W and less than 10000W, and the number of cycles is less than or equal to 35%n;

[0067] S203, forming a second aluminum oxide layer on the first aluminum oxide layer, wherein a deposition power during the formation of the second aluminum oxide layer is greater than or equal to 10000w and less than 15000w;

[0068] The implementation of S201, S202, and S203 is Figure 1 S101, S102, and S103 in the embodiment are similar and will not be described in detail in this embodiment.

[0069] S204, forming a silicon nitride layer or a silicon nitride oxide layer on the second aluminum oxide layer.

[0070] Specifically, the forming of a silicon nitride layer or a silicon oxynitride layer on the second aluminum oxide layer includes:

[0071] The silicon nitride layer or silicon oxynitride layer is deposited on the second aluminum oxide layer using a PECVD process. Further, the silicon nitride layer or silicon oxynitride layer is deposited on the second aluminum oxide layer using a PECVD process, including: depositing a first silicon nitride layer or a first silicon oxynitride layer on the front aluminum oxide layer, wherein the deposition temperature of the first silicon nitride layer or the first silicon oxynitride layer is greater than or equal to 450°C and less than 500°C. Exemplarily, the deposition temperature is 450°C, 460°C, 470°C, and 490°C, and is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable. In this embodiment, the temperature for depositing the first silicon nitride layer or the first silicon oxynitride layer is greater than or equal to 450°C and less than 500°C. In this embodiment, the temperature for depositing the first silicon nitride layer or the first silicon oxynitride layer is a relatively low temperature, which can reduce damage to the first silicon nitride layer or the first silicon oxynitride layer.

[0072] Further, a second silicon nitride layer or a second silicon nitride oxide layer is deposited on the first silicon nitride layer or the first silicon nitride oxide layer, wherein the deposition temperature of the second silicon nitride layer or the second silicon nitride oxide layer is greater than or equal to 500°C and less than or equal to 560°C. Exemplarily, the deposition temperature is 500°C, 520°C, 540°C, 560°C, and is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable. The growth temperature of the second silicon nitride layer or the second silicon nitride oxide layer of this embodiment can meet the high temperature annealing of the front aluminum oxide layer and improve the quality of the passivation layer.

[0073] The first silicon nitride layer or the first silicon oxynitride layer of this embodiment is grown by plasma enhanced chemical vapor deposition process, and the initial deposition temperature of the first silicon nitride layer or the first silicon oxynitride layer is relatively low, which can reduce the damage to the first silicon nitride layer or the first silicon oxynitride layer. Since the aluminum oxide layer needs a certain high temperature for annealing to improve the passivation effect of the aluminum oxide layer, the growth temperature of the second silicon nitride layer or the second silicon oxynitride layer of this embodiment is relatively high temperature, which can meet the requirements of low temperature growth of silicon nitride layer or silicon oxynitride layer, and high temperature annealing of the front aluminum oxide layer, thereby improving the quality of the passivation layer and improving the efficiency of the solar cell.

[0074] The following table shows the test data comparing the TOPCon cell manufactured by the manufacturing method of this embodiment (Example 1: the deposition temperature of the first silicon nitride layer is 470°C; Example 2: the deposition temperature of the first silicon nitride layer is 450°C) with the TOPCon cell manufactured by the existing manufacturing method (Comparative example: the deposition temperature of the first silicon nitride layer is 535°C).

[0075]

[0076] Table 3 Test data of embodiments and comparative examples

[0077] It can be seen from Table 3 that compared with the conventional TOPCon cell produced by growing the first silicon nitride layer at 535° C. in the comparative example, the conversion efficiency of the TOPCon cell produced by growing the first silicon nitride layer at 450° C. and 470° C. in this embodiment is significantly improved.

[0078] Figure 3 For a flow chart of the solar cell manufacturing method provided in the embodiment of the present application, please refer to Figure 3 The solar cell manufacturing method of the embodiment of the present invention comprises the following steps:

[0079] S301, forming a boron diffusion layer on the front side of the silicon substrate;

[0080] S302, sequentially forming a tunneling oxide layer and a doped polysilicon layer on the back side of the silicon substrate;

[0081] The back of the silicon substrate is first etched and tunneled to form a tunneling oxide layer, and amorphous silicon is doped in situ, annealed, and de-plated to form a doped polysilicon layer. Specifically, the silicon wafer with boron expansion is etched on a chain acid etching machine, and the volume concentration of HN03 in the etching tank is 1%-20%, and the volume concentration of HF is 1%-20%. Thermal oxidation is used, and the oxidation temperature is 500-700℃ to obtain a tunneling oxide layer located on the back. PH3 and SiH4 mixed gas are used, and the PECVD method is used for preparation, and the process temperature is 200-600℃. The silicon wafer after amorphous silicon is kept at a constant temperature of 700-1000℃ for 1-120min. After annealing, silicon oxide is grown on the back of the silicon wafer, and the silicon oxide in the front winding area is washed away with HF (volume concentration 1%-40%), and then placed in an alkaline polishing tank (KOH volume concentration 1%-20%, temperature 40-90°C, alkaline polishing additive 2-20L) for alkaline polishing to remove the front polysilicon winding and obtain a doped polysilicon layer on the tunneling oxide layer on the back.

[0082] S303, forming a first aluminum oxide layer on the boron diffusion layer, wherein the deposition power during the formation of the first aluminum oxide layer is greater than or equal to 7500w and less than 10000w, and the number of cycles is less than or equal to 35%n;

[0083] S304, forming a second aluminum oxide layer on the first aluminum oxide layer, wherein a deposition power during the formation of the second aluminum oxide layer is greater than or equal to 10000w and less than 15000w;

[0084] S305 , sequentially depositing a back aluminum oxide layer and a silicon nitride layer on the doped polysilicon layer using a plasma enhanced atomic layer deposition process.

[0085] Specifically, in this embodiment, a front aluminum oxide layer is formed on the boron diffusion layer while a back aluminum oxide layer is formed on the doped polysilicon layer. By forming the front aluminum oxide layer on the boron diffusion layer and the back aluminum oxide layer on the doped polysilicon layer at the same time, the manufacturing efficiency of the solar cell can be improved. Moreover, the front aluminum oxide layer and the back aluminum oxide layer are formed at the same time, so that the thickness of the front aluminum oxide layer and the back aluminum oxide layer can be almost equal.

[0086] The implementation of S301, S303, and S304 in this embodiment is similar to Figure 1 S101, S102, and S103 in the embodiment are similar and will not be described in detail in this embodiment.

[0087] It should be understood that the numbering of the above steps S301-S305 is for the convenience of technicians to understand the implementation order. In actual implementation, the implementation may not be carried out in the order of the numbers. For example, S305 may be implemented before S303. The numbering order of steps S301-S305 in the above embodiment should not be understood as a limitation on the implementation order.

[0088] The TOPCon battery manufacturing method provided in the embodiment of the present application includes: manufacturing a boron diffusion layer on the front side of a silicon substrate, manufacturing a front aluminum oxide layer on the boron diffusion layer, and manufacturing the front aluminum oxide layer on the boron diffusion layer using a plasma enhanced atomic layer deposition process, wherein the number of cycles of the plasma enhanced atomic layer deposition process is less than or equal to 80, and manufacturing the front aluminum oxide layer includes: depositing a first aluminum oxide layer on the boron diffusion layer using a plasma enhanced atomic layer deposition method, wherein the deposition power of the first aluminum oxide layer is greater than or equal to 7500w and less than 10000w, and the number of cycles is less than or equal to 35. %n; A second aluminum oxide layer is formed on a first aluminum oxide layer by a plasma enhanced atomic layer deposition method, and a deposition power of the second aluminum oxide layer is greater than or equal to 10000w and less than 15000w. The TOPCon battery manufacturing method manufactures the first aluminum oxide layer at low power and then manufactures the second aluminum oxide layer at high power. Since low power is used when manufacturing the first aluminum oxide layer, damage to the boron diffusion layer is reduced. The deposition power for manufacturing the second aluminum oxide layer is high power, and the deposition speed is fast and the density is good, thereby improving the quality of the TOPCon battery and improving the efficiency of the TOPCon battery.

[0089] A second aspect of the present embodiment provides a solar cell, which is manufactured by the solar cell manufacturing method described in the above embodiment.

[0090] The first aluminum oxide layer of the front aluminum oxide layer of the solar cell of this embodiment is produced at low power, and the second aluminum oxide layer is produced at high power. Since low power is used when producing the first aluminum oxide layer, the damage to the boron diffusion layer is reduced. The deposition power for producing the second aluminum oxide layer is high power, the deposition speed is fast, and the density is good, which improves the quality of the solar cell and improves the efficiency of the solar cell.

[0091] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

[0092] In the above description, the description with reference to the terms "an embodiment", "some embodiments", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

Claims

1. A method for manufacturing a solar cell, characterized in that: include: forming a boron diffusion layer on the front side of the silicon substrate; A front aluminum oxide layer is formed on the boron diffusion layer by a plasma enhanced atomic layer deposition process, the number of cycles of the plasma enhanced atomic layer deposition process is n, and n is less than or equal to 80. The forming of the front aluminum oxide layer includes: A first aluminum oxide layer is formed on the boron diffusion layer, wherein a deposition power during the formation of the first aluminum oxide layer is greater than or equal to 7500W and less than 10000W, and the number of cycles is less than or equal to 35%n; Fabricating a second aluminum oxide layer on the first aluminum oxide layer, wherein a deposition power during the fabrication of the second aluminum oxide layer is greater than or equal to 10000w and less than 15000w; After forming the second aluminum oxide layer on the first aluminum oxide layer, the method further includes: depositing a silicon nitride layer or a silicon oxynitride layer on the second aluminum oxide layer using a plasma enhanced chemical vapor deposition process.

2. The method for manufacturing a solar cell according to claim 1, characterized in that: The thickness of the first aluminum oxide layer is greater than or equal to 0.3 nm and less than or equal to 0.6 nm, and the thickness of the second aluminum oxide layer is greater than or equal to 2 nm and less than or equal to 4 nm.

3. The method for manufacturing a solar cell according to claim 1, characterized in that: The deposition power during the production of the first aluminum oxide layer is greater than or equal to 9000W and less than or equal to 9600W, and the deposition power during the production of the second aluminum oxide layer is greater than or equal to 10000W and less than or equal to 12000W.

4. The method for manufacturing a solar cell according to claim 1, characterized in that: The step of depositing the silicon nitride layer or the silicon oxynitride layer on the second aluminum oxide layer using a plasma enhanced chemical vapor deposition process comprises: A first silicon nitride layer or a first silicon nitride oxide layer is deposited on the second aluminum oxide layer, wherein a deposition temperature of the first silicon nitride layer or the first silicon nitride oxide layer is greater than or equal to 460° C. and less than 500° C.

5. The method for manufacturing a solar cell according to claim 4, characterized in that: A second silicon nitride layer or a second silicon nitride oxide layer is deposited on the first silicon nitride layer or the first silicon nitride oxide layer, wherein a deposition temperature of the second silicon nitride layer or the second silicon nitride oxide layer is greater than or equal to 500° C. and less than or equal to 560° C.

6. The method for manufacturing a solar cell according to any one of claims 1 to 5, characterized in that: After forming a boron diffusion layer on the front side of the silicon substrate, the method further comprises: forming a tunneling oxide layer and a doped polysilicon layer in sequence on the back side of the silicon substrate; A plasma enhanced atomic layer deposition process is adopted to sequentially deposit a back aluminum oxide layer and a silicon nitride layer on the doped polysilicon layer.

7. The method for manufacturing a solar cell according to claim 6, characterized in that: The front aluminum oxide layer is formed on the boron diffusion layer, and the back aluminum oxide layer is formed on the doped polysilicon layer at the same time.

8. A solar cell, characterized in that: The solar cell is manufactured by the solar cell manufacturing method described in any one of claims 1 to 7.

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