Film coating method of solar cell, film layer, solar cell and photovoltaic module

Abstract

The invention relates to the technical field of solar cells, and discloses a film coating method of a solar cell, a film layer, the solar cell and a photovoltaic module. The coating method is carried out by adopting coating equipment, and the coating equipment comprises a process pipe as well as a main body heating structure and an auxiliary heating structure which are arranged on the process pipe; the coating method comprises the steps that heating pretreatment is conducted, specifically, a main body heating structure is started to heat a process pipe where a to-be-coated part is placed, the main body heating structure is configured to heat the interior of the process pipe to a first actual temperature according to a preset temperature, and the first actual temperature is 430-510 DEG C lower than the preset temperature; depositing a film layer: keeping the main body heating structure to be started, starting the auxiliary heating structure so as to increase the temperature in the process pipe to a second actual temperature, introducing reaction gas into the process pipe in which the to-be-coated piece is placed, and depositing the film layer on the to-be-coated piece; the second actual temperature is the preset temperature or is closer to the preset temperature than the first actual temperature. By adopting the film coating method, the compactness of a film layer is relatively high, and the film explosion degree is relatively low.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a film coating method of a solar cell, a film layer, a solar cell and a photovoltaic module. BACKGROUND

[0002] For the production and processing of solar cells, the film coating process is very important, which will affect the quality of film coating, thereby affecting the photoelectric conversion performance and yield of the solar cell.

[0003] Among them, the compactness of the film layer will affect the performance and film burst degree of the film layer, and the higher the compactness, the better the performance of the film layer, and the lower the compactness, the lower the film burst degree, so the requirements for compactness are opposite, so how to improve the performance of the film layer while reducing the film burst degree is a problem that needs to be solved by those skilled in the art. SUMMARY

[0004] The film coating method, the film layer, the solar cell and the photovoltaic module disclosed by the embodiments of the present application have high compactness, good performance and low film burst degree.

[0005] In a first aspect, the embodiments of the present application disclose a film coating method of a solar cell, which is performed by a film coating device, wherein the film coating device comprises a process tube and a main heating structure and an auxiliary heating structure arranged on the process tube;

[0006] The film coating method comprises the following steps:

[0007] Temperature rising pretreatment: the main heating structure is turned on to heat the process tube, and the main heating structure is configured to heat the process tube in the process tube to a first actual temperature according to a preset temperature, and the first actual temperature is less than the preset temperature; wherein the process tube is placed with a film coating piece to be coated, and the preset temperature is 430-510 DEG C;

[0008] Depositing a film layer: keeping the main heating structure turned on, and turning on the auxiliary heating structure to heat the process tube, so that the process tube is heated to a second actual temperature, and the reaction gas is introduced into the process tube where the film coating piece to be coated is placed, and the film layer is deposited on the film coating piece to be coated; wherein the second actual temperature is the preset temperature, or the second actual temperature is closer to the preset temperature than the first actual temperature.

[0009] Further, in the step of depositing the film layer, the parameters of the auxiliary heating structure include:

[0010] The ratio of the actual current of the auxiliary heating structure to the rated current is X, the X is 25%-30%, and the auxiliary heating temperature is 490-510 DEG C.

[0011] Further, the step of introducing the reaction gas into the process tube in which the workpiece is placed comprises:

[0012] The reaction gas is introduced into the process tube in which the workpiece is placed, and the first deposition, the second deposition, the third deposition, and the fourth deposition are performed to deposit the film layer on the workpiece.

[0013] Further, the process tube comprises a furnace mouth region, a furnace tail region, and a furnace middle region between the furnace mouth region and the furnace tail region.

[0014] In the step of the first deposition, the parameters of the auxiliary heating structure comprise: the auxiliary heating time is 70s-75s, the X of the furnace mouth region is 25%-28%, the X of the furnace middle region is 27%-30%, and the X of the furnace tail region is 27%-30%; and / or,

[0015] In the step of the second deposition, the parameters of the auxiliary heating structure comprise: the auxiliary heating time is 80s-85s, the X of the furnace mouth region is 25%-28%, the X of the furnace middle region is 27%-30%, and the X of the furnace tail region is 27%-30%; and / or,

[0016] In the step of the third deposition, the parameters of the auxiliary heating structure comprise: the auxiliary heating time is 130s-135s, the X of the furnace mouth region is 25%-28%, the X of the furnace middle region is 27%-30%, and the X of the furnace tail region is 27%-30%; and / or,

[0017] In the step of the fourth deposition, the parameters of the auxiliary heating structure comprise: the auxiliary heating time is 280s-295s, the X of the furnace mouth region is 25%-28%, the X of the furnace middle region is 27%-30%, and the X of the furnace tail region is 27%-30%.

[0018] Further, the preset temperature is 480℃-510℃; and / or,

[0019] The reaction gas comprises silane and ammonia, the flow rate of the silane is 500sccm-4000sccm, and the flow rate of the ammonia is 2000sccm-20000sccm; and / or,

[0020] In the step of depositing the film layer, the auxiliary heating time of the auxiliary heating structure is equal to or less than the heating time of the main heating structure.

[0021] Further, after the step of the temperature rising pretreatment and before the step of the deposition film layer, the film coating method further comprises:

[0022] The process pipe in which the part to be coated is placed is subjected to a first constant voltage treatment, a pre-deposition treatment and a second constant voltage treatment, the main heating structure is kept on, and the auxiliary heating structure is turned on.

[0023] Further, the process pipe comprises a furnace mouth area, a furnace tail area, and a furnace middle area between the furnace mouth area and the furnace tail area, and the ratio of the actual current to the rated current of the auxiliary heating structure is X;

[0024] In the step of the first constant voltage treatment, the parameters of the auxiliary heating structure comprise: the auxiliary heating time is 5s-10s, the auxiliary heating temperature is 490℃-510℃, the X of the furnace mouth area is 32%-37%, the X of the furnace middle area is 42%-47%, and the X of the furnace tail area is 42%-47%; and / or,

[0025] In the step of the pre-deposition treatment, the parameters of the auxiliary heating structure comprise: the auxiliary heating time is 35s-40s, the auxiliary heating temperature is 490℃-510℃, the X of the furnace mouth area is 28%-33%, the X of the furnace middle area is 38%-42%, and the X of the furnace tail area is 37%-43%; and / or,

[0026] In the step of the second constant voltage treatment, the parameters of the auxiliary heating structure comprise: the auxiliary heating time is 10s-15s, the auxiliary heating temperature is 490℃-510℃, the auxiliary heating time is 35s-40s, the X of the furnace mouth area is 28%-33%, the X of the furnace middle area is 33%-37%, and the X of the furnace tail area is 33%-37%.

[0027] Further, the process pipe comprises a furnace mouth area, a furnace tail area, and a furnace middle area between the furnace mouth area and the furnace tail area;

[0028] The step of the temperature rising pretreatment further comprises: turning on the main heating structure to heat the process pipe, and turning on the auxiliary heating structure to heat the process pipe;

[0029] In the step of the temperature rising pretreatment, the X of the furnace mouth area presents a downward trend, and the X of the furnace middle area presents a downward trend.

[0030] Further, the step of the temperature rising pretreatment comprises:

[0031] The process pipe in which the to-be-coated part is placed is subjected to temperature rising treatment, constant temperature treatment, vacuumizing treatment, back pressure treatment, and leak detection treatment.

[0032] In the temperature rising treatment, the parameters of the auxiliary heating structure include: auxiliary heating time of 650s-700s, auxiliary heating temperature of 490℃-510℃, X of the furnace mouth region of 78%-82%, X of the furnace middle region of 83%-87%, and X of the furnace tail region of 83%-87%; and / or,

[0033] In the constant temperature treatment, the parameters of the auxiliary heating structure include: auxiliary heating time of 30s-40s, auxiliary heating temperature of 490℃-510℃, X of the furnace mouth region of 73%-77%, X of the furnace middle region of 78%-82%, and X of the furnace tail region of 83%-87%; and / or,

[0034] In the vacuumizing treatment, the parameters of the auxiliary heating structure include: auxiliary heating time of 170s-180s, auxiliary heating temperature of 490℃-510℃, X of the furnace mouth region of 58%-62%, X of the furnace middle region of 68%-72%, and X of the furnace tail region of 68%-72%; and / or,

[0035] In the back pressure treatment, the auxiliary heating parameters of the auxiliary heating structure include: auxiliary heating time of 25s-30s, auxiliary heating temperature of 490℃-510℃, X of the furnace mouth region of 43%-47%, X of the furnace middle region of 58%-62%, and X of the furnace tail region of 58%-62%; and / or,

[0036] In the leak detection treatment, the parameters of the auxiliary heating structure include: auxiliary heating time of 25s-30s, auxiliary heating temperature of 490℃-510℃, X of the furnace mouth region of 32%-37%, X of the furnace middle region of 42%-47%, and X of the furnace tail region of 42%-47%.

[0037] Further, before the temperature rising pre-treatment, the coating method further includes: sending the to-be-coated part into the process pipe, and starting the main heating structure and the auxiliary heating structure to heat the process pipe.

[0038] Further, the process pipe includes a furnace mouth region, a furnace tail region, and a furnace middle region between the furnace mouth region and the furnace tail region.

[0039] The parameter of the auxiliary heating structure in the step of sending the component to be plated into the process tube includes: the auxiliary heating time is 110s-120s, and the auxiliary heating temperature is 490℃-510℃.

[0040] The ratio of the actual current to the rated current of the auxiliary heating structure is X, the X of the furnace mouth area is 78%-82%, the X of the furnace middle area is 83%-87%, and the X of the furnace tail area is 83%-87%.

[0041] In a second aspect, the embodiments of the present application disclose a film layer, which is prepared by the film plating method of any one of the first aspect.

[0042] Further, the thickness of the film layer is 82nm-86nm; and / or,

[0043] The in-sheet thickness uniformity of any one of the film layers is 2%-4%; and / or,

[0044] The inter-sheet thickness uniformity of the plurality of film layers located in different areas of the process tube is 5%-6%.

[0045] In a third aspect, the embodiments of the present application disclose a solar cell, which comprises the film layer of any one of the second aspect.

[0046] In a fourth aspect, the embodiments of the present application disclose a photovoltaic module, which comprises the solar cell of the third aspect.

[0047] Compared with the prior art, the beneficial effects of the present application are as follows:

[0048] The film plating method of the present application can improve the compactness of the film layer and help reduce the risk of film explosion.

[0049] Specifically, the film plating method of the present application is performed in a film plating device, which comprises a process tube, a main heating structure and an auxiliary heating structure located on the process tube. In the step of temperature rising pretreatment, the process tube is first heated by the main heating structure, so that the process tube is heated to a first actual temperature under the action of the main heating structure. However, the first actual temperature cannot directly reach the preset temperature, i.e. the first actual temperature is less than the preset temperature.

[0050] Further, in the step of depositing the film layer, the auxiliary heating structure is further turned on to heat the process tube on the basis of keeping the main body heating structure turned on, the auxiliary heating structure has a compensating effect on the temperature difference between the first actual temperature and the preset temperature, so that the second actual temperature of the process tube is closer to or equal to the preset temperature 430-510℃ under the joint action of the auxiliary heating structure and the main body heating structure. Therefore, when the temperature of the process tube reaches the second actual temperature, it is helpful to improve the activity of the reaction gas introduced into the process tube, enhance the reaction sufficiency between the reaction gases, and further improve the compactness of the film layer; and in this process, since the temperature of the process tube reaches the second actual temperature which is closer to or equal to the preset temperature, the second actual temperature can provide more energy to promote the breaking of chemical bonds such as silicon-hydrogen bond and nitrogen-hydrogen bond, so that the hydrogen ions are dissociated in the process of film plating, and then the hydrogen ions will recombine into hydrogen gas and be discharged from the process tube. In this way, since the hydrogen content in the film layer is reduced in the film plating stage, the degree of film explosion caused by subsequent high-temperature operations such as sintering to make electrodes can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0052] Figure 1 is a process flow chart of a first film plating method provided by the embodiments of the present application;

[0053] Figure 2 is a process flow chart of depositing a film layer provided by the embodiments of the present application;

[0054] Figure 3 is a process flow chart of a second film plating method provided by the embodiments of the present application;

[0055] Figure 4 is a process flow chart of a third film plating method provided by the embodiments of the present application;

[0056] Figure 5 is a process flow chart of a temperature rising pretreatment provided by the embodiments of the present application;

[0057] Figure 6 is a process flow chart of a fourth film plating method provided by the embodiments of the present application. DETAILED DESCRIPTION

[0058] Clearly, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present application.

[0059] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not intended to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0060] In addition, in addition to being used to indicate the orientation or positional relationship, the above-mentioned partial terms can also be used to indicate other meanings, for example, the term "upper" can also be used to indicate a certain dependent relationship or connection relationship in some cases. Those of ordinary skill in the art can understand the specific meaning of these terms in the present application according to the specific circumstances.

[0061] In addition, the terms "first", "second", and the like are mainly used to distinguish different devices, elements or components (the specific types and structures can be the same or different), and are not intended to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, the meaning of "multiple" is two or more.

[0062] The technical solutions provided by the present application will be further described below in conjunction with the embodiments and the drawings.

[0063] In the film layer deposition process of the solar cell, the deposition quality of the film layer will affect the yield and efficiency of the solar cell. Specifically, when there are defects and pinholes in the film layer, the film layer will have lower compactness, which will cause the performance of the film layer to be damaged; when the compactness of the film layer is higher, in the subsequent sintering process of the metal electrode, the resistance of hydrogen gas overflow in the film layer is larger, which will form internal pressure in the film layer, and when the internal pressure exceeds the strength of the film layer, the film layer will have the risk of burst.

[0064] Therefore, improving the performance of the film layer requires preparing a film layer structure with higher compactness; reducing the risk of film explosion requires preparing a film layer with appropriate porosity, reducing the compactness of the film layer, so that the hydrogen gas in the film layer can overflow through the pores to reduce the risk of film explosion. That is, the requirements of the film layer performance and the film layer explosion degree on the compactness are opposite, higher film layer compactness will promote the improvement of the film layer performance, but will also cause the increase of the film explosion degree; lower film layer compactness will damage the film layer performance, but will also reduce the risk of film explosion.

[0065] Based on the above problems, the embodiments of the present application provide a film coating method of a solar cell, a film layer, a solar cell, and a photovoltaic module. The film coating method is used to prepare a film layer with higher compactness, good performance, and lower film explosion degree.

[0066] The embodiments of the present application disclose a film coating method of a solar cell, which is performed by using a film coating device. The film coating device includes a process tube and a main heating structure and an auxiliary heating structure arranged on the process tube.

[0067] As shown in the film coating method includes the following steps: Figure 1

[0068] Temperature rising pretreatment: the main heating structure is turned on to heat the process tube. The main heating structure is configured to heat the process tube in the process tube to a first actual temperature according to a preset temperature. The first actual temperature is lower than the preset temperature. The process tube is placed with a piece to be coated. The preset temperature is 430-510°C.

[0069] Depositing a film layer: the main heating structure is kept on, and the auxiliary heating structure is turned on to heat the process tube, so that the process tube is heated to a second actual temperature. The reaction gas is introduced into the process tube with the piece to be coated, and the film layer is deposited on the piece to be coated. The second actual temperature is the preset temperature, or the second actual temperature is closer to the preset temperature than the first actual temperature.

[0070] The actual temperature of the process tube can be measured by using a thermocouple instrument. The instrument is placed in a high-temperature resistant protection box, and the test line of the instrument is placed at the position to be tested (for example, on the cell in the region of the furnace). Then the instrument is sent into the process tube for testing. If the actual temperature of the process tube in a certain step is to be obtained, for example, the temperature in the temperature rising pretreatment step, the corresponding test result can be read after the process is completed. The present application does not limit the specific test method as long as the purpose of the present application can be achieved.

[0071] ​Further, the preset temperature refers to the temperature set by the main heating structure, which is the ideal temperature during the process processing; the actual temperature refers to the real temperature that the process tube can reach after being heated by the heating structure. Moreover, the main heating structure refers to the core component that undertakes the main heating task of the process tube, provides the basic temperature or temperature rising power for the process tube, so that the actual temperature in the process tube can approach the preset temperature but not reach the preset temperature; the auxiliary heating structure refers to the auxiliary component for cooperating with the main heating structure to provide additional heat, thereby optimizing the actual temperature of the process tube to make it closer to or even reach the preset temperature. Moreover, the auxiliary heating structure can be a heating wire or a heating pipe, when the auxiliary heating structure is a heating wire, the heating wire is wrapped around the pipe wall of the process tube, when the auxiliary heating structure is a heating pipe, the heating pipe is located below the to-be-coated piece; the main heating structure can be a heating plate, and the heating plate can be arranged below the to-be-coated piece. The present application does not limit the types of auxiliary heating structure and main heating structure as long as the effect of the present application can be achieved.

[0072] In addition, in the process processing of the to-be-coated piece, in order to facilitate the processing of the to-be-coated piece, the to-be-coated piece can be placed in the carrier boat, and the loading and ionization effect of the carrier boat is used to realize the processing of the to-be-coated piece. Moreover, the number of carrier boats can be one or more, for example, the number of carrier boats is two, the to-be-coated pieces are placed on the two carrier boats, and the two carrier boats are placed in the process tube in turn to realize the simultaneous processing of the two carrier boats. Moreover, the carrier boat can be a graphite boat, the to-be-coated piece can be a silicon wafer, and the process tube can be a PECVD furnace tube.

[0073] The coating method of the present application is carried out in a coating equipment, and the coating equipment includes a process tube, a main heating structure and an auxiliary heating structure located on the process tube. During the temperature rising pretreatment, the main heating structure first heats the process tube, and under the action of the main heating structure, the process tube will be heated to a first actual temperature, and the first actual temperature is less than the preset temperature.

[0074] And, in the step of heating pre-treatment, since the first actual temperature of the process tube is less than the preset temperature, in the step of depositing the film layer, the auxiliary heating structure is further opened to heat the process tube on the basis of keeping the main heating structure open, and the auxiliary heating structure has a compensating effect on the temperature difference between the actual temperature and the preset temperature of the process tube. The temperature difference is derived from the difference between the first actual temperature and the preset temperature, and in the step of depositing the film layer, the introduction of the reaction gas and the discharge of the impurity gas will affect the temperature of the process tube, so the auxiliary heating structure is opened to help reduce the temperature difference, that is, under the joint action of the auxiliary heating structure and the main heating structure, the second actual temperature of the process tube is closer to or equal to the preset temperature 430-510°C. Exemplarily, the preset temperature is 430°C, 450°C, 460°C, 480°C, 510°C, etc.

[0075] Therefore, when the temperature of the process tube reaches the second actual temperature, it helps to improve the activity of the reaction gas and enhance the reaction sufficiency between the reaction gases, thereby helping to improve the density of the film layer; and in the process, since the temperature of the process tube reaches the second actual temperature, the second actual temperature can provide more energy to promote the breaking of chemical bonds such as silicon-hydrogen bonds and nitrogen-hydrogen bonds, so that hydrogen ions are dissociated, and then the hydrogen ions will recombine into hydrogen gas and be discharged from the process tube, so as to help reduce the content of hydrogen gas in the film layer and reduce the degree of film explosion of the film layer.

[0076] More preferably, when the preset temperature is 480-510°C, the heat in the process tube is more, which is more helpful to promote the formation of a film layer with higher density and lower film explosion degree, thereby helping to improve the performance of the solar cell.

[0077] Further, in the step of depositing the film layer, the parameters of the auxiliary heating structure include:

[0078] The ratio of the actual current of the auxiliary heating structure to the rated current is X, X is 25%-30%, and the auxiliary heating temperature is 490-510°C. The auxiliary heating temperature refers to the temperature set by the auxiliary heating structure, which can cooperate with the temperature of the main heating structure to form a common heating effect.

[0079] When X and the auxiliary heating temperature are within the above range, the auxiliary heating structure can effectively optimize the actual temperature of the process tube, so that the second actual temperature in the process tube is closer to or equal to the preset temperature. Therefore, it helps to further improve the activity of the reaction molecules, ensure that the prepared film layer has fewer defects and pinholes, and improve the density of the film layer; it can also promote the hydrogen ions to become hydrogen gas and escape in the form of hydrogen gas, thereby avoiding the existence of hydrogen gas or hydrogen ions in the film layer, reducing the hydrogen content in the film layer to a higher degree, and reducing the degree of film explosion. And the above range of X can effectively cope with the temperature change caused by the introduction of reaction gas and the discharge of impurity gas, so that the second actual temperature can be kept within a stable range, which is more helpful for preparing a film layer with high density and lower film explosion degree. For example, X is 25%, 26%, 28%, 29%, 30%, etc.; the auxiliary heating temperature is 490°C, 495°C, 500°C, 505°C, 510°C, etc.

[0080] In the present application, the rated current value of the auxiliary heating structure can reach 75A-90A. At this current, by further controlling the ratio of the actual current to the rated current, the heating effect can be improved, so that the auxiliary heating structure can efficiently reduce the temperature difference.

[0081] In addition, when preparing a film layer on a film-plated part, the preparation method includes the following two schemes. In one optional embodiment, the step of introducing reaction gas into the process tube in which the film-plated part is placed includes: introducing reaction gas into the process tube in which the film-plated part is placed, and performing one-time deposition to deposit a film layer on the film-plated part. In another optional embodiment, as shown in Figure 2 the step of introducing reaction gas into the process tube in which the film-plated part is placed includes: introducing reaction gas into the process tube in which the film-plated part is placed, and performing first deposition, second deposition, third deposition, and fourth deposition to deposit a film layer on the film-plated part through multiple depositions.

[0082] When the film layer is prepared on the surface of the film-plated part by the method of multiple depositions, this kind of deposition can release the stress of the film layer, so that the deposition quality of the film layer is higher, which helps to avoid stress accumulation; and when multiple depositions are performed, the film layers also have pores, which is more helpful for the overflow of hydrogen gas. Therefore, it helps to improve the structural stability of the film layer to a higher degree.

[0083] Further, the process tube includes a furnace mouth area, a furnace tail area, and a furnace middle area between the furnace mouth area and the furnace tail area; in the first deposition step, the parameters of the auxiliary heating structure include: the auxiliary heating time is 70s-75s, X of the furnace mouth area is 25%-28%, X of the furnace middle area is 27%-30%, and X of the furnace tail area is 27%-30%.

[0084] In the step of the second deposition, the parameters of the auxiliary heating structure include: the auxiliary heating time is 80s-85s, X of the furnace mouth area is 25%-28%, X of the furnace area is 27%-30%, and X of the furnace tail area is 27%-30%.

[0085] In the step of the third deposition, the parameters of the auxiliary heating structure include: the auxiliary heating time is 130s-135s, X of the furnace mouth area is 25%-28%, X of the furnace area is 27%-30%, and X of the furnace tail area is 27%-30%.

[0086] In the step of the fourth deposition, the parameters of the auxiliary heating structure include: the auxiliary heating time is 280s-295s, X of the furnace mouth area is 25%-28%, X of the furnace area is 27%-30%, and X of the furnace tail area is 27%-30%.

[0087] In the step of depositing the film layer, the introduction of the reaction gas and the exhaust of the impurity gas will affect the actual temperature in the process tube, so the application controls the parameters of the auxiliary heating structure in the four deposition steps to meet the above range, so that the auxiliary heating structure can effectively compensate the temperature, thereby effectively promoting the second actual temperature to be closer to or the preset temperature, and further helping to improve the molecular reaction activity of the reaction gas to a higher degree, improve the denseness of the film layer, reduce the hydrogen content in the film layer, and reduce the degree of film explosion.

[0088] In addition, in the step of depositing the film layer, the deposition power of the film layer is 15000W-20000W. In addition, it should be noted that when depositing each film layer, the deposition power is set according to the single wafer boat configuration single power, that is, when multiple wafer boats are used, the corresponding deposition power is set on any wafer boat, and the deposition power on each wafer boat can be the same or different. When the deposition power of each wafer boat is the same, the uniformity of the quality of the deposited film layer in each wafer boat can be effectively ensured. For example, when the number of wafer boats is two, the deposition power is applied to the two wafer boats, and the deposition power of the two wafer boats is the same, thereby ensuring that the quality uniformity of the film layer prepared in the two wafer boats is high.

[0089] Further, the reaction gas includes silane and ammonia, the flow rate of the silane is 500sccm-4000sccm, and the flow rate of the ammonia is 2000sccm-20000sccm; when the reaction gas is ammonia and silane, and the flow rates of the silane and the ammonia are controlled within the above range, the reaction sufficiency of the reaction gas can be effectively improved, the quality of the deposited film layer can be ensured, and the actual temperature of the process tube can be ensured not to be greatly affected, so that the second actual temperature after being heated by the auxiliary heating structure can effectively play its role.

[0090] In addition, silane and ammonia contain nitrogen-hydrogen bonds and silicon-hydrogen bonds. Therefore, by controlling the flow rate within the above range, the content of hydrogen produced by their decomposition can be effectively controlled. Thus, under the heating action of the auxiliary heating structure and the main heating structure, the hydrogen in the above reaction gas can be discharged to a higher extent in the form of hydrogen gas, reducing the hydrogen content in the film layer and thus reducing the degree of film rupture.

[0091] For example, the flow rate of silane is 500 sccm, 1000 sccm, 2000 sccm, 3000 sccm, 4000 sccm, etc.; the flow rate of ammonia is 2000 sccm, 5000 sccm, 10000 sccm, 15000 sccm, 20000 sccm, etc.

[0092] Furthermore, in the film deposition step, the auxiliary heating time of the auxiliary heating structure is equal to or less than the heating time of the main heating structure. Since the auxiliary heating structure can compensate for the first actual temperature of the main heating structure, the second actual temperature obtained after their combined action is closer to or equal to the preset temperature. Therefore, the auxiliary heating time is related to the heating time of the main heating structure, and thus, the auxiliary heating time is equal to or less than the heating time of the main heating structure. Preferably, when the heating time of the main heating structure and the auxiliary heating time are equal, it is more conducive to optimizing the actual temperature of the process tube, making the second actual temperature closer to or equal to the preset temperature, thereby significantly improving the film performance and reducing the problem of film bursting.

[0093] Furthermore, such as Figure 3 As shown, in the coating method of this application embodiment, after the heating pretreatment step and before the film deposition step, the coating method further includes:

[0094] The process tube containing the part to be coated is subjected to a first constant pressure treatment, a pre-deposition treatment, and a second constant pressure treatment, while keeping the main heating structure on and the auxiliary heating structure on.

[0095] Since the auxiliary heating structure is turned on at the beginning of the above steps and is not turned off after the steps are completed, the auxiliary heating structure is also turned on during the deposition of the film layer, which helps to further optimize the second actual temperature of the process tube.

[0096] When the auxiliary heating structure is turned on in the above step, it prepares for the film layer deposition step, so as to help promote the second actual temperature to be closer to the preset temperature, or even reach the preset temperature, so that the second actual temperature can further provide suitable energy, which helps to improve the molecular activity of the reaction gas to a higher degree, and further promotes the escape of hydrogen.

[0097] Further, the ratio of the actual current of the auxiliary heating structure to the rated current is X;

[0098] In the first constant voltage treatment step, the parameters of the auxiliary heating structure include: auxiliary heating time of 5s-10s, auxiliary heating temperature of 490-510℃, X of the furnace mouth area of 32%-37%, X of the furnace area of 42%-47%, and X of the furnace tail area of 42%-47%.

[0099] In the pre-deposition treatment step, the parameters of the auxiliary heating structure include: auxiliary heating time of 35s-40s, auxiliary heating temperature of 490-510℃, X of the furnace mouth area of 28%-33%, X of the furnace area of 38%-42%, and X of the furnace tail area of 37%-43%.

[0100] In the second constant voltage treatment step, the parameters of the auxiliary heating structure include: auxiliary heating time of 10s-15s, auxiliary heating temperature of 490-510℃, auxiliary heating time of 35s-40s, X of the furnace mouth area of 28%-33%, X of the furnace area of 33%-37%, and X of the furnace tail area of 33%-37%.

[0101] By controlling the auxiliary heating parameters in the above steps within the above ranges, it helps to ensure that it can better compensate for the temperature difference between the first actual temperature and the preset temperature, thereby helping to prepare for the deposition of the film layer and improving the quality of the subsequent preparation of the film layer.

[0102] In addition, during the second constant voltage treatment, the reaction gas can be further introduced, and the flow rate of the reaction gas is close to that in the film layer deposition step. Therefore, by the first constant voltage treatment, the pre-deposition treatment, and the second constant voltage treatment, the preparation for the deposition of the film layer is made, so that during the deposition of the film layer, the pressure of the process tube has high stability, and the introduction of the reaction gas does not cause the pressure to fluctuate, which makes it difficult to effectively ensure the deposition quality of the film layer.

[0103] Further, as shown in Figure 4 the temperature rising pre-treatment step further includes: turning on the main heating structure to heat the process tube, and turning on the auxiliary heating structure to heat the process tube.

[0104] The ratio of the actual current of the auxiliary heating structure to the rated current is X, and in the step of the temperature rising pretreatment, the X of the furnace mouth area presents a downward trend, and the X of the furnace area presents a downward trend.

[0105] In the step of the temperature rising pretreatment, the auxiliary heating structure is turned on, and the auxiliary heating structure is not turned off after the step is completed, so that the auxiliary heating structure in the subsequent film deposition step is also in an open state, which helps to further optimize the second actual temperature of the process tube.

[0106] By turning on the auxiliary heating structure in the step and setting the ratio of the actual current to the rated current of the auxiliary heating structure to present a downward trend, the temperature difference between the first actual temperature and the preset temperature is reduced to a higher degree; and the first actual temperature in the process tube can be closer to the preset temperature, which helps to increase the heat energy in the process tube, and then promotes the hydrogen ions in the process tube to become hydrogen gas, which is discharged from the process tube, reduces the hydrogen content of the process tube, and thus helps to avoid entering the film layer, which causes the film layer to burst. And because the auxiliary heating structure is in an open state during the temperature rising pretreatment, when the first actual temperature is relatively stable, the heat provided by the auxiliary heating structure can make up for the temperature difference between different areas of the process tube, so that the temperature of different areas of the process tube has good uniformity, further ensuring the quality of the subsequent deposition film.

[0107] Further, as shown in Figure 5 The step of the temperature rising pretreatment comprises:

[0108] The process tube in which the to-be-coated part is placed is subjected to temperature rising treatment, constant temperature treatment, vacuumizing treatment, back pressure treatment, and leak detection treatment.

[0109] In the step of the temperature rising treatment, the parameters of the auxiliary heating structure include: the auxiliary heating time is 650s-700s, the auxiliary heating temperature is 490℃-510℃, the X of the furnace mouth area is 78%-82%, the X of the furnace area is 83%-87%, and the X of the furnace tail area is 83%-87%.

[0110] In the step of the constant temperature treatment, the parameters of the auxiliary heating structure include: the auxiliary heating time is 30s-40s, the auxiliary heating temperature is 490℃-510℃, the X of the furnace mouth area is 73%-77%, the X of the furnace area is 78%-82%, and the X of the furnace tail area is 83%-87%.

[0111] In the step of the vacuumizing treatment, the parameters of the auxiliary heating structure include: the auxiliary heating time is 170s-180s, the auxiliary heating temperature is 490℃-510℃, the X of the furnace mouth area is 58%-62%, the X of the furnace area is 68%-72%, and the X of the furnace tail area is 68%-72%.

[0112] In the back pressure treatment step, the auxiliary heating parameters of the auxiliary heating structure include: auxiliary heating time of 25s to 30s, auxiliary heating temperature of 490℃ to 510℃, X of 43% to 47% in the furnace mouth area, X of 58% to 62% in the furnace middle area, and X of 58% to 62% in the furnace tail area.

[0113] In the leak detection process, the parameters of the auxiliary heating structure include: auxiliary heating time of 25s to 30s, auxiliary heating temperature of 490℃ to 510℃, X of 32% to 37% in the furnace mouth area, X of 42% to 47% in the furnace middle area, and X of 42% to 47% in the furnace tail area.

[0114] First, the above steps can all be used to confirm whether the process tube meets the requirements for film deposition, such as whether the temperature of the process tube is stable, whether there is air leakage in the process tube, and whether there is pressure instability. Second, by controlling the parameters in the auxiliary heating structure of the above steps within the above range, this application enables the first actual temperature of the process tube to reach a relatively stable state and makes the first actual temperature closer to the preset temperature. Therefore, the heat energy provided by the second actual temperature in the film deposition step is more effective, thereby helping to improve the performance of the film to a greater extent.

[0115] Furthermore, such as Figure 6 As shown, before the heating pretreatment step, the coating method further includes: sending the part to be coated into the process tube, and turning on the main heating structure and auxiliary heating structure to heat the process tube.

[0116] Furthermore, since the auxiliary heating structure and the main heating structure are turned on in the above steps, and the auxiliary heating structure is not turned off after the steps are completed, the auxiliary heating structure in subsequent steps is also turned on, which helps to further optimize the second actual temperature of the process tube.

[0117] In the process of feeding the part to be coated into the process tube, the opening of the furnace door will cause the temperature inside the process tube to drop sharply. However, this application replenishes the heat to the process tube by activating the auxiliary heating structure and the main heating structure in this step, so that the actual temperature of the process tube can be maintained within a certain range, avoiding a large temperature difference between the actual temperature and the preset temperature in the process tube. This helps to make the first actual temperature closer to the preset temperature, thereby helping to improve the deposition quality of the film.

[0118] Furthermore, in the step of feeding the part to be coated into the process tube, the parameters of the auxiliary heating structure include: auxiliary heating time of 110s to 120s and auxiliary heating temperature of 490℃ to 510℃.

[0119] The ratio of the actual current of the auxiliary heating structure to the rated current is X, X of the furnace mouth area is 78% to 82%, X of the furnace middle area is 83% to 87%, and X of the furnace tail area is 83% to 87%.

[0120] The auxiliary heating parameter helps to ensure that the actual temperature of the process tube and the preset temperature do not differ too much, thereby helping to improve the deposition quality of the film layer to a higher degree.

[0121] In addition, more preferably, the main heating structure and the auxiliary heating structure are in the open state from the step of sending the film plating part into the process tube to the step of depositing the film layer. In this embodiment, since the heating structure is always in the open state, the first actual temperature can reach a stable state, which makes the first actual temperature closer to the preset temperature, or even reach the preset temperature.

[0122] Further, in the step of depositing the film layer, the opening of the auxiliary heating structure is equivalent to the effect of heat preservation, so that the second preset temperature can reach a stable state when it is closer to or even reaches the preset temperature, thereby making the deposition quality of the film layer higher.

[0123] For example, the auxiliary heating time is 110s, 112s, 114s, 118s, 120s, etc., the auxiliary heating temperature is 490℃, 495℃, 500℃, 505℃, 510℃, etc., X of the furnace mouth area is 78%, 79%, 80%, 81%, 82%, etc., and X of the furnace middle area and the furnace tail area is 83%, 84%, 85%, 86%, 87%, etc.

[0124] The application further discloses a film layer prepared by the film plating method.

[0125] Further, the thickness of the film layer is 82nm to 86nm; when the thickness of the film layer is within the above range, it means that the film layer has good effect and can effectively improve the performance of the solar cell. For example, the thickness of the film layer is 82nm, 83nm, 84nm, 85nm, 86nm, etc.

[0126] The in-sheet thickness uniformity of any film layer is 2% to 4%; wherein the in-sheet thickness uniformity refers to the film thickness uniformity of different areas of a film layer. When the uniformity is within the above range, it means that the thickness difference of different areas of the film layer is small, and the quality of the film layer is high, which is more helpful for preparing a solar cell with high performance. For example, the thickness uniformity is 2%, 2.5%, 3%, 3.5%, 4%, etc.

[0127] The inter-plate thickness uniformity of the plurality of film layers located at different regions of the process tube is 5% to 6%, wherein the inter-plate uniformity refers to the uniformity of the thickness of the film layers located at different regions of the process tube. When the thickness uniformity is within the above range, it indicates that the deposition thickness of the film layers located at different regions of the process tube is less different, and the deposition quality of the film layers is higher. Exemplarily, the thickness uniformity is 5%, 5.2%, 5.4%, 5.6%, 5.6%, 6%, etc.

[0128] In addition, the thickness in the present application refers to the average thickness. When the thickness is tested, it is a value obtained by calculating the thickness values measured at a plurality of positions of the film layer, which reflects the overall thickness level of the film layer in the thickness direction. The above film layer thickness can be tested by an ellipsometer, for example, at least five points are taken on the film layer, and the average value of the measurement data is obtained by measuring the thickness values of the five points respectively. In addition, the ellipsometer can be tested by the ellipsometer of the German sentch company, model SE-800. The present application does not limit the specific method of testing, as long as the purpose of the present application can be achieved.

[0129] The intra-plate thickness uniformity is obtained by first taking point measurements of the thickness of different positions of a film layer, and calculating the uniformity of the film thickness according to the maximum value and the minimum value, the uniformity=(maximum value-minimum value) / (maximum value+minimum value). For example, five points are taken on a film layer, and the intra-plate thickness uniformity is obtained by measuring and calculating the five points.

[0130] The inter-plate thickness uniformity is obtained by first extracting film-coated parts at different regions, and then testing the film layers on the extracted film-coated parts respectively, measuring the average value of any film thickness, and then calculating the uniformity of the film thickness at different regions according to the maximum value and the minimum value, the uniformity=(maximum value-minimum value) / (maximum value+minimum value). For example, 24 film-coated parts are taken at different regions on a carrier boat, the average value of the film layer thickness on any film-coated part is tested, and the inter-plate thickness uniformity is obtained by calculating the test data of the 24 film-coated parts.

[0131] The present application further discloses a solar cell, which comprises the above film layer.

[0132] The present application further discloses a photovoltaic module, which comprises the above solar cell.

[0133] The technical solutions of the present application will be further explained in combination with more specific embodiments and experimental test results.

[0134] Embodiment one:

[0135] The present application provides a preparation method of a solar cell:

[0136] S1, the N-type silicon substrate is textured to form a textured surface on the silicon substrate.

[0137] S2, the silicon substrate is placed in a quartz boat after saturated process cleaning, the quartz boat is placed in a process tube, BCl3 is introduced for diffusion at 850-1050°C to form a PN junction and a wrap-around layer on the back surface and / or side edge of the silicon substrate, and the sheet resistance of the light-receiving surface after diffusion is 120-140Ω / sq.

[0138] S3, a chain-type HF device is used to remove the boron-containing glass body on the back surface of the silicon wafer due to boron diffusion, and a slot-type wet device is used to remove the wrap-around layer on the back surface and side edge of the silicon substrate, and the back surface of the silicon substrate is polished.

[0139] S4, a passivation contact structure is prepared on the back surface of the silicon substrate, the passivation contact structure includes a dielectric layer with a thickness of 1.2 nm, and a doped amorphous silicon layer with a thickness of 80 nm disposed on the side of the dielectric layer away from the silicon substrate, and a film-coated piece is prepared, which is a silicon wafer.

[0140] S5, a silicon nitride layer is prepared on the light-receiving surface and the back surface of the silicon substrate by a PECVD method, and the film-coating method of the silicon nitride layer includes:

[0141] The film-coating method includes the following steps:

[0142] S5.1, the silicon wafer is sent into a process tube, the main heating structure and the auxiliary heating structure are turned on to heat the process tube, and the parameters of the auxiliary heating structure include: auxiliary heating time of 120 s, auxiliary heating temperature of 500°C, X of the furnace mouth area of 80%, X of the furnace area of 85%, X of the furnace tail area of 85%, preset temperature of the main heating structure of 500°C, time of 120 s, and pressure of 1000 bar;

[0143] S5.2, temperature rising pretreatment: the main heating structure and the auxiliary heating structure are kept on, and the main heating structure is configured to heat the process tube to a first actual temperature according to the preset temperature of 500°C, and the first actual temperature is less than the preset temperature; wherein the first actual temperature is 475°C;

[0144] S5.2.1, in the step of temperature rising treatment, the parameters of the auxiliary heating structure include: auxiliary heating time of 700 s, auxiliary heating temperature of 500°C, X of the furnace mouth area of 80%, X of the furnace area of 85%, X of the furnace tail area of 85%, preset temperature of the main heating structure of 500°C, time of 700 s, and pressure of 1000 bar;

[0145] In the step of the isothermal treatment, the parameters of the auxiliary heating structure include: the auxiliary heating time is 40s, the auxiliary heating temperature is 500℃, X of the mouth area is 75%, X of the middle area is 80%, X of the tail area is 85%, the preset temperature of the main heating structure is 500℃, the time is 40s, and the pressure is 1000bar;

[0146] In the step of the evacuation treatment, the parameters of the auxiliary heating structure include: the auxiliary heating time is 180s, the auxiliary heating temperature is 500℃, X of the mouth area is 60%, X of the middle area is 70%, X of the tail area is 70%, the preset temperature of the main heating structure is 500℃, the time is 180s, and the pressure is 0bar;

[0147] In the step of the back pressure treatment, the parameters of the auxiliary heating structure include: the auxiliary heating time is 30s, the auxiliary heating temperature is 500℃, X of the mouth area is 45%, X of the middle area is 60%, X of the tail area is 60%, the preset temperature of the main heating structure is 500℃, the time is 30s, and the pressure is 10000bar;

[0148] In the step of the leak detection treatment, the parameters of the auxiliary heating structure include: the auxiliary heating time is 30s, the auxiliary heating temperature is 500℃, X of the mouth area is 35%, X of the middle area is 45%, X of the tail area is 45%, the preset temperature of the main heating structure is 500℃, the time is 30s, and the pressure is 0bar.

[0149] In the step of the first isothermal treatment, the main heating structure and the auxiliary heating structure are kept on, the parameters of the auxiliary heating structure include: the auxiliary heating time is 10s, the auxiliary heating temperature is 500℃, X of the mouth area is 35%, X of the middle area is 45%, X of the tail area is 45%, the preset temperature of the main heating structure is 500℃, the time is 10s, the pressure is 1000bar, and the ammonia flow is 10000sccm;

[0150] In the step of the pre-deposition treatment, the main heating structure and the auxiliary heating structure are kept on, the parameters of the auxiliary heating structure include: the auxiliary heating time is 40s, the auxiliary heating temperature is 500℃, X of the mouth area is 30%, X of the middle area is 40%, X of the tail area is 40%, the preset temperature of the main heating structure is 500℃, the time is 10s, the pressure is 1000bar, power 1 is 15000W, power 2 is 20000W, and the ammonia flow is 15000sccm;

[0151] S5.5 In the step of the second constant voltage treatment, the main heating structure and the auxiliary heating structure are kept on, and the parameters of the auxiliary heating structure include: the auxiliary heating time is 15s, the auxiliary heating temperature is 500℃, X of the furnace mouth area is 30%, X of the furnace area is 35%, X of the furnace tail area is 35%, the preset temperature of the main heating structure is 500℃, the time is 15s, the pressure is 800bar, the ammonia flow is 10000sccm, and the silane flow is 1000sccm.

[0152] S5.6 Depositing a film layer: the main heating structure and the auxiliary heating structure are kept on to heat the process tube to a second actual temperature, and the reaction gas is introduced into the process tube where the silicon wafer is placed to deposit a silicon nitride film layer on the silicon wafer; wherein the second actual temperature is 495℃, the thickness of the silicon nitride film layer is 84nm, the within-wafer thickness uniformity is 3%, and the between-wafer thickness uniformity is 5.5%:

[0153] S5.6.1 In the step of the first deposition, the parameters of the auxiliary heating structure include: the auxiliary heating time is 75s, X of the furnace mouth area is 25%, X of the furnace area is 30%, X of the furnace tail area is 30%, the preset temperature of the main heating structure is 500℃, the time is 75s, the pressure is 1000bar, power 1 is 15000W, power 2 is 20000W, the ammonia flow is 15000sccm, and the silane flow is 1000sccm;

[0154] S5.6.2 In the step of the second deposition, the parameters of the auxiliary heating structure include: the auxiliary heating time is 85s, X of the furnace mouth area is 25%, X of the furnace area is 30%, X of the furnace tail area is 30%, the preset temperature of the main heating structure is 500℃, the time is 85s, the pressure is 1000bar, power 1 is 15000W, power 2 is 20000W, the ammonia flow is 15000sccm, and the silane flow is 1000sccm;

[0155] S5.6.3 In the step of the third deposition, the parameters of the auxiliary heating structure include: the auxiliary heating time is 135s, X of the furnace mouth area is 25%, X of the furnace area is 30%, X of the furnace tail area is 30%, the preset temperature of the main heating structure is 500℃, the time is 135s, the pressure is 1000bar, power 1 is 15000W, power 2 is 20000W, the ammonia flow is 15000sccm, and the silane flow is 1000sccm;

[0156] S5.6.4 In the fourth deposition step, the parameters of the auxiliary heating structure include: the auxiliary heating time is 295 s, the X of the mouth area is 25%, the X of the middle area is 30%, the X of the tail area is 30%, the preset temperature of the main heating structure is 500℃, the time is 295 s, the pressure is 1000 bar, the power 1 is 15000 W, the power 2 is 20000 W, the ammonia flow is 15000 sccm, and the silane flow is 1000 sccm.

[0157] S6 The negative electrode is prepared on the nitride silicon layer of the back light surface, the positive electrode is prepared on the nitride silicon layer of the light receiving surface, and the solar cell is prepared.

[0158] Example Two:

[0159] The difference between this example and Example One is that the preset temperature is 430℃.

[0160] Example Three:

[0161] The difference between this example and Example One is that the preset temperature is 480℃.

[0162] Example Four:

[0163] The difference between this example and Example One is that the preset temperature is 510℃.

[0164] Example Five:

[0165] The difference between this example and Example One is that in the step of depositing the film layer, in the fourth deposition step, the X of the mouth area is 20%, the X of the middle area is 40%, and the X of the tail area is 30%.

[0166] Example Six:

[0167] The difference between this example and Example One is that in the temperature rising pretreatment step, the X of the mouth area and the middle area are the same, i.e., the X of the mouth area is 60% and the X of the middle area is 55%.

[0168] Example Seven:

[0169] The difference between this example and Example One is that after the silicon wafer is sent into the process tube, only the main heating structure is turned on to heat the process tube.

[0170] Comparative Example One:

[0171] The difference between this comparative example and Example One is that only the auxiliary heating structure is turned on in the temperature rising pretreatment step, and only the main heating structure is turned on in the step of depositing the film layer.

[0172] Comparative Example Two:

[0173] The difference between the present comparative example and Example 1 is that the preset temperature is 410℃.

[0174] Comparative Example 3

[0175] The difference between the present comparative example and Example 1 is that the preset temperature is 520℃.

[0176] Comparative Example 4

[0177] The difference between the present comparative example and Example 1 is that only the main heating structure is turned on during the whole coating process.

[0178] Performance test

[0179] The solar cells prepared in Examples 1-7 and Comparative Examples 1-4 are subjected to the following relevant tests:

[0180] The open circuit voltage, short circuit current and fill factor of the solar cells are tested by using a tester with the model of GIV-60 produced by Zhongsen Electric Power Technology Co., Ltd. The silicon wafer of the tested solar cell has a size of 210mm x 105mm, and the calibrated light intensity is 1000±5W / m 2 . The experimental test results are as follows.

[0181] Table 1 Performance test results of solar cells

[0182]

[0183]

[0184] As can be seen from the data of Example 1 and Comparative Example 1, the photoelectric conversion efficiency of Example 1 is better than that of Comparative Example 1. It can be seen that in the step of depositing the film layer, the auxiliary heating structure of Example 1 is turned on, and then under the synergistic heating action of the auxiliary heating structure and the main heating structure, the second actual temperature of the process tube is closer to or equal to the preset temperature, which helps to increase the reaction sufficiency of the reaction gas, improve the denseness of the film layer, promote the breaking of the silicon-hydrogen bond and the nitrogen-hydrogen bond, and make the hydrogen ions dissociate into hydrogen gas and be discharged from the process tube, thereby helping to reduce the film layer explosion degree.

[0185] As can be seen from the data of Examples 1-4 and Comparative Examples 2 and 3, the photoelectric conversion efficiency of Examples 1-4 is better than that of Comparative Examples 2 and 3. It can be seen that when the preset temperature is in the range of 430℃-510℃, not only the reaction activity of the reaction gas can be effectively improved, but also the dissociation probability of the silicon-hydrogen bond and the nitrogen-hydrogen bond can be increased, and the dissociated hydrogen ions can be further recombined into hydrogen gas, thereby helping to prepare a film layer with high denseness and low film layer explosion degree.

[0186] In addition, it can be known from analyzing the data of the first to fourth embodiments that the photoelectric conversion efficiency of the first, third and fourth embodiments is better than that of the second embodiment. It can be seen that the preset temperature value of the first, third and fourth embodiments is better, and the better preset temperature value can provide more suitable energy, thereby helping to prepare a film layer with higher compactness and lower blistering degree.

[0187] It can be known from analyzing the data of the first and fourth comparative examples that the photoelectric conversion efficiency of the first embodiment is better than that of the fourth comparative example. It can be seen that the auxiliary heating structure is turned on during the entire film coating process, and then under the synergistic action of the auxiliary heating structure and the main heating structure, the difference between the first actual temperature of the process tube during the temperature rising pretreatment and the preset temperature is smaller, so as to further make the second actual temperature closer to or equal to the preset temperature, thereby helping to improve the reaction activity of the reaction gas, promote the escape of hydrogen, and form a film layer with high compactness and low blistering degree.

[0188] It can be known from analyzing the data of the first and fifth embodiments that the photoelectric conversion efficiency of the first embodiment is better than that of the fifth embodiment. It can be seen that when the X of the furnace mouth area, the furnace area and the furnace tail area is less than or equal to 30%, it can effectively cope with the temperature change caused by the introduction of the reaction gas and the discharge of the impurity gas, which makes the second actual temperature in the process tube stable and closer to or equal to the preset temperature, so as to help to prepare a film layer with higher compactness and lower blistering degree.

[0189] It can be known from analyzing the data of the first and sixth embodiments that the photoelectric conversion efficiency of the first embodiment is better than that of the sixth embodiment. It can be seen that in the temperature rising pretreatment step, the X in the furnace mouth area and the furnace area presents a downward trend, so that the first actual temperature in the process tube can be closer to the preset temperature, which helps to increase the heat energy in the process tube, thereby promoting the hydrogen ions in the process tube to become hydrogen gas; and helps to make up for the temperature difference of different areas of the process tube, so that the temperature of different areas of the process tube has good uniformity, further ensuring the quality of the subsequent deposited film layer.

[0190] It can be known from analyzing the data of the first and seventh embodiments that the photoelectric conversion efficiency of the first embodiment is better than that of the seventh embodiment. It can be seen that the auxiliary heating structure is turned on in the step of sending the silicon wafer into the process tube, and under the common heating of the auxiliary heating structure and the main heating structure, the heat loss caused by the opening of the furnace door can be made up, which helps to avoid the high temperature difference between the actual temperature in the process tube and the preset temperature, so that the first actual temperature in the process tube is closer to the preset temperature, thereby helping to improve the deposition quality of the film layer.

[0191] The coating method of the solar cell, the film layer, the solar cell and the photovoltaic module disclosed in the embodiments of the present application are described in detail, and the principles and implementation manners of the present application are described by using specific examples. The above embodiment description is only used to help understand the coating method of the solar cell, the film layer, the solar cell and the photovoltaic module. Meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manner and application range can be changed, and the above description should not be understood as a limitation of the present application.

Claims

1. A method of coating a solar cell, characterized by, The coating method is performed by using a coating device, the coating device comprises a process tube, a main heating structure and an auxiliary heating structure arranged on the process tube; The coating method comprises the following steps: Preheating: the main heating structure is turned on to heat the process tube, the main heating structure is configured to heat the process tube to a first actual temperature which is less than a preset temperature, the preset temperature is 430-510 DEG C; wherein, the process tube is placed with a piece to be coated, the preset temperature is 430-510 DEG C; Depositing a film layer: the main heating structure is kept on, and the auxiliary heating structure is turned on to heat the process tube, so that the process tube is heated to a second actual temperature, the reaction gas is introduced into the process tube placed with the piece to be coated, and the film layer is deposited on the piece to be coated; wherein, the second actual temperature is the preset temperature, or the second actual temperature is closer to the preset temperature than the first actual temperature.

2. The coating method according to claim 1, wherein In the step of depositing a film layer, the parameters of the auxiliary heating structure include: The ratio of the actual current of the auxiliary heating structure to the rated current is X, the X is 25-30%, and the auxiliary heating temperature is 490-510 DEG C.

3. The coating method according to claim 2, wherein The step of introducing the reaction gas into the process tube placed with the piece to be coated comprises: The reaction gas is introduced into the process tube placed with the piece to be coated to perform first deposition, second deposition, third deposition and fourth deposition, so as to deposit the film layer on the piece to be coated.

4. The coating method according to claim 3, wherein The process tube comprises a furnace mouth area, a furnace tail area and a furnace middle area between the furnace mouth area and the furnace tail area; In the step of first deposition, the parameters of the auxiliary heating structure include: the auxiliary heating time is 70-75 s, the X of the furnace mouth area is 25-28%, the X of the furnace middle area is 27-30%, and the X of the furnace tail area is 27-30%; and / or, In the step of second deposition, the parameters of the auxiliary heating structure include: the auxiliary heating time is 80-85 s, the X of the furnace mouth area is 25-28%, the X of the furnace middle area is 27-30%, and the X of the furnace tail area is 27-30%; and / or, In the step of third deposition, the parameters of the auxiliary heating structure include: the auxiliary heating time is 130-135 s, the X of the furnace mouth area is 25-28%, the X of the furnace middle area is 27-30%, and the X of the furnace tail area is 27-30%; and / or, In the step of fourth deposition, the parameters of the auxiliary heating structure include: the auxiliary heating time is 280-295 s, the X of the furnace mouth area is 25-28%, the X of the furnace middle area is 27-30%, and the X of the furnace tail area is 27-30%.

5. The coating method according to claim 1, wherein The process tube comprises a furnace mouth region, a furnace tail region, and a furnace middle region between the furnace mouth region and the furnace tail region, a ratio of an actual current of the auxiliary heating structure to a rated current is X, after the step of the temperature rising pre-treatment and before the step of the deposition film layer, the film plating method further comprises: performing a first constant voltage treatment, a pre-deposition treatment and a second constant voltage treatment on the process tube in which the to-be-plated member is placed, keeping the main heating structure open, and turning on the auxiliary heating structure; In the step of the first constant voltage treatment, parameters of the auxiliary heating structure include: an auxiliary heating time of 5s-10s, an auxiliary heating temperature of 490℃-510℃, the X of the furnace mouth region is 32%-37%, the X of the furnace middle region is 42%-47%, and the X of the furnace tail region is 42%-47%; and / or, In the step of the pre-deposition treatment, parameters of the auxiliary heating structure include: an auxiliary heating time of 35s-40s, an auxiliary heating temperature of 490℃-510℃, the X of the furnace mouth region is 28%-33%, the X of the furnace middle region is 38%-42%, and the X of the furnace tail region is 37%-43%; and / or, In the step of the second constant voltage treatment, parameters of the auxiliary heating structure include: an auxiliary heating time of 10s-15s, an auxiliary heating temperature of 490℃-510℃, an auxiliary heating time of 35s-40s, the X of the furnace mouth region is 28%-33%, the X of the furnace middle region is 33%-37%, and the X of the furnace tail region is 33%-37%.

6. The coating method according to claim 1, wherein The process tube comprises a furnace mouth region, a furnace tail region, and a furnace middle region between the furnace mouth region and the furnace tail region; The step of the temperature rising pre-treatment further comprises: turning on the main heating structure to heat the process tube, and turning on the auxiliary heating structure to heat the process tube; In the step of the temperature rising pre-treatment, the X of the furnace mouth region presents a downward trend, and the X of the furnace middle region presents a downward trend.

7. The coating method according to claim 6, wherein The step of the temperature rising pre-treatment comprises: performing a temperature rising treatment, a constant temperature treatment, an evacuation treatment, a back pressure treatment, and a leak detection treatment on the process tube in which the to-be-plated member is placed; In the step of the temperature rising treatment, parameters of the auxiliary heating structure include: an auxiliary heating time of 650s-700s, an auxiliary heating temperature of 490℃-510℃, the X of the furnace mouth region is 78%-82%, the X of the furnace middle region is 83%-87%, and the X of the furnace tail region is 83%-87%; and / or, In the step of the constant temperature treatment, parameters of the auxiliary heating structure include: an auxiliary heating time of 30s-40s, an auxiliary heating temperature of 490℃-510℃, the X of the furnace mouth region is 73%-77%, the X of the furnace middle region is 78%-82%, and the X of the furnace tail region is 83%-87%; and / or, In the step of the evacuating process, the parameters of the auxiliary heating structure include: the auxiliary heating time is 170s-180s, the auxiliary heating temperature is 490℃-510℃, the X of the mouth region is 58%-62%, the X of the middle region is 68%-72%, and the X of the tail region is 68%-72%; and / or, In the step of the back pressure process, the auxiliary heating parameters of the auxiliary heating structure include: the auxiliary heating time is 25s-30s, the auxiliary heating temperature is 490℃-510℃, the X of the mouth region is 43%-47%, the X of the middle region is 58%-62%, and the X of the tail region is 58%-62%; and / or, In the step of the leak detection process, the parameters of the auxiliary heating structure include: the auxiliary heating time is 25s-30s, the auxiliary heating temperature is 490℃-510℃, the X of the mouth region is 32%-37%, the X of the middle region is 42%-47%, and the X of the tail region is 42%-47%.

8. The coating method according to any one of claims 1 to 7, characterized in that, The process tube includes a mouth region, a tail region, and a middle region between the mouth region and the tail region, and before the step of the temperature rising pre-process, the film coating method further includes: sending the piece to be coated into the process tube, and starting the main heating structure and the auxiliary heating structure to heat the process tube; The parameters of the auxiliary heating structure include: the auxiliary heating time is 110s-120s, and the auxiliary heating temperature is 490℃-510℃. The ratio of the actual current of the auxiliary heating structure to the rated current is X, the X of the mouth region is 78%-82%, the X of the middle region is 83%-87%, and the X of the tail region is 83%-87%; and / or, The preset temperature is 480℃-510℃; and / or, The reaction gas includes silane and ammonia, the flow rate of the silane is 500sccm-4000sccm, and the flow rate of the ammonia is 2000sccm-20000sccm; and / or, In the step of depositing the film layer, the auxiliary heating time of the auxiliary heating structure is equal to or less than the heating time of the main heating structure.

9. A film layer, characterized by, The film layer is prepared by the film coating method of any one of claims 1-8.

10. The film layer of claim 9, wherein, The thickness of the film layer is 82nm-86nm; and / or, The in-sheet thickness uniformity of any one of the film layers is 2%-4%; and / or, The inter-sheet thickness uniformity of the multiple film layers in different regions of the process tube is 5%-6%.

11. A solar cell, characterized by The solar cell includes the film layer of any one of claims 9-10.

12. A photovoltaic module, characterized by The photovoltaic module includes the solar cell of claim 11.

Images