Preparation method of TBC battery and TBC battery

Abstract

The embodiment of the invention discloses a preparation method of a TBC battery and the TBC battery. The preparation method comprises the following steps: firstly, forming a mask film layer on a first surface of an N-type silicon substrate; wherein the N-type silicon substrate comprises a first surface and a second surface which are deviated from each other, then laser grooving processing is carried out on one side, away from the first surface, of the mask film layer to form a first area and a second area which are alternately arranged in an interdigital mode, then boron-silicon slurry is printed in the first area, sintering processing is carried out on the N-type silicon substrate printed with the boron-silicon slurry, and the N-type silicon substrate is obtained. And finally, forming a first passivation film layer on the surface of one side, far away from the first surface, of the mask film layer, and carrying out silk-screen printing and sintering treatment on the first passivation film layer to form an electrode structure so as to prepare the TBC battery. By utilizing the method, boron diffusion doping is realized by adopting the boron-silicon slurry, the photoelectric conversion efficiency of the TBC battery is improved, and the open-circuit voltage value of the TBC battery is improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of solar cells, and in particular to a method for preparing a TBC cell and a TBC cell. Background Art

[0002] TBC cells are crystalline silicon solar cells with a back contact structure. They are a structure with TOPCon (Tunnel Oxide Passivated Contact) superimposed on BC (Back Contact) technology. On the back of the cell, there are high-quality P and N regions arranged in interdigitated patterns. The characteristics of TBC cells are that the PN junction and metal contact are both on the back of the cell, and the front side (i.e., the light-receiving side) is not affected by any metal grid lines, so it has a higher short-circuit current. At the same time, the back side can allow for wider metal grid lines to reduce the series resistance and thus increase the fill factor. In addition, the open-circuit voltage gain brought about by the front surface field of the cell and good passivation makes the photoelectric conversion efficiency of this type of cell with no obstruction on the front side high.

[0003] At present, N-type TBC cells use N-type silicon wafers as raw materials. In the conventional process flow, the TOPcon structure is retained in the N+ area, and the laser grooving method is used in the P area to retain the doping of the original N-type silicon wafer, and the electrode structure is formed in the P area by laser film opening and printing aluminum paste. However, when the N-type silicon wafer cools from high temperature, the aluminum element in the aluminum paste is easy to form aluminum thorns, destroying the PN junction on the N-type silicon wafer, and forming a metal composite area, which can easily affect the open circuit voltage value and photoelectric conversion efficiency of the TBC cell. Summary of the invention

[0004] The embodiment of the present invention provides a method for preparing a TBC battery and a TBC battery, which solves the problem of low open circuit voltage and photoelectric conversion efficiency of existing N-type TBC batteries.

[0005] In a first aspect, an embodiment of the present invention provides a method for preparing a TBC battery, comprising:

[0006] Forming a mask film layer on the first surface of the N-type silicon substrate; wherein the N-type silicon substrate comprises the first surface and the second surface which are opposite to each other, and the first surface is a polished surface, and the second surface is a velvet surface;

[0007] Performing a laser grooving process on a side of the mask film layer away from the first surface to form a first region and a second region alternately arranged in an interdigitated shape;

[0008] Printing borosilicate paste in the first region, and sintering the N-type silicon substrate printed with the borosilicate paste to perform boron diffusion doping on the first region;

[0009] A first passivation film layer is formed on a surface of the mask film layer away from the first surface, and screen printing and sintering are performed on the first passivation film layer to form an electrode structure, thereby manufacturing the TBC battery.

[0010] Optionally, after printing borosilicate slurry in the first region and sintering the N-type silicon substrate printed with the borosilicate slurry to perform boron diffusion doping on the first region, the method further includes:

[0011] The N-type silicon substrate after sintering is subjected to oxidation degradation treatment.

[0012] Optionally, before forming the mask film layer on the first surface of the N-type silicon substrate, the method further includes:

[0013] forming a passivation contact film layer on the first surface of the N-type silicon substrate, and performing a phosphorus diffusion doping process on a side of the passivation contact film layer away from the first surface;

[0014] Forming a mask film layer on the first surface of the N-type silicon substrate, comprising:

[0015] forming the mask film layer on a surface of the passivation contact film layer away from the first surface;

[0016] Laser grooving is performed on a side of the mask film layer away from the first surface to form first and second regions alternately arranged in an interdigitated manner, including:

[0017] A laser groove process is performed on a side of the mask film layer corresponding to the first region away from the first surface, so that the bottom of the groove structure corresponding to the first region is located in the passivation contact film layer.

[0018] Optionally, screen printing and sintering are performed on the first passivation film layer to form an electrode structure to obtain the TBC battery, including:

[0019] Printing silver paste on the first passivation film layer corresponding to the first region and on the first passivation film layer corresponding to the second region respectively;

[0020] The N-type silicon substrate printed with the silver paste is sintered to form a first metal gate line in contact with the first region and a second metal gate line in contact with the second region.

[0021] Optionally, the material of the first passivation film layer includes silicon nitride.

[0022] Optionally, after printing borosilicate slurry in the first region and sintering the N-type silicon substrate printed with the borosilicate slurry to perform boron diffusion doping on the first region, the method further includes:

[0023] An anti-ultraviolet attenuation film layer and a second passivation film layer are sequentially formed on the second surface of the N-type silicon substrate.

[0024] Optionally, the material of the anti-ultraviolet attenuation film layer includes aluminum oxide; and / or the material of the second passivation film layer includes silicon nitride.

[0025] Optionally, the mask film layer includes a first mask layer, a second mask layer and a third mask layer;

[0026] Forming a mask film layer on the first surface of the N-type silicon substrate, comprising:

[0027] Performing thermal oxidation treatment on one side of the first surface of the N-type silicon substrate to form the first mask layer;

[0028] Performing a coating process on a side of the first mask layer away from the first surface to form the second mask layer;

[0029] A thermal oxidation treatment is performed on a side of the second mask layer away from the first surface to form the third mask layer.

[0030] Optionally, the material of the first mask layer includes silicon oxide; and / or, the material of the second mask layer includes silicon nitride; and / or, the material of the third mask layer includes silicon oxide.

[0031] In a second aspect, an embodiment of the present invention further provides a TBC battery, which is prepared using the TBC battery preparation method as described in any one of the first aspects.

[0032] An embodiment of the present invention provides a method for preparing a TBC battery and a TBC battery. The preparation method first forms a mask film layer on the first surface of an N-type silicon substrate; wherein the N-type silicon substrate includes a first surface and a second surface that are opposite to each other, and the first surface is a polished surface, and the second surface is a velvet surface; then, a laser groove is performed on a side of the mask film layer away from the first surface to form a first region and a second region that are alternately arranged in a forked shape; then, borosilicate slurry is printed in the first region, and the N-type silicon substrate printed with the borosilicate slurry is sintered to perform boron diffusion doping on the first region; finally, a first passivation film layer is formed on a surface of the side of the mask film layer away from the first surface, and screen printing and sintering are performed on the first passivation film layer to form an electrode structure to obtain a TBC battery. By using the above method, a laser groove is performed on a side of the mask film layer away from the first surface to form a first region corresponding to the grooved structure and a second region corresponding to the ungrooved structure, and boron diffusion doping is achieved in the first region using borosilicate slurry, and conventional phosphorus diffusion doping is used in the second region, thereby increasing the doping in the first region and reducing the metal composite in the first region. The borosilicate slurry is easier to achieve the boron diffusion effect, and also avoids the formation of aluminum thorns caused by the use of aluminum paste, destroying the PN junction on the N-type silicon wafer, and forming a metal composite region, thereby reducing the contact resistivity of the TBC battery, improving the photoelectric conversion efficiency of the TBC battery, and improving the open circuit voltage value of the TBC battery, thereby solving the problem of low open circuit voltage value and photoelectric conversion efficiency of the existing N-type TBC battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 It is a schematic flow chart of a method for preparing a TBC battery provided in an embodiment of the present invention;

[0035] Figure 2 It is a schematic flow chart of another method for preparing a TBC battery provided in an embodiment of the present invention;

[0036] Figure 3 It is a schematic flow chart of another method for preparing a TBC battery provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0038] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. It should be noted that the directional words such as "upper", "lower", "left", "right" and the like described in the embodiments of the present invention are described at the angles shown in the accompanying drawings and should not be understood as limitations on the embodiments of the present invention. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is formed "on" or "under" another element, it can not only be directly formed "on" or "under" another element, but also indirectly formed "on" or "under" another element through an intermediate element. The terms "first", "second", etc. are only used for descriptive purposes and do not represent any order, quantity or importance, but are only used to distinguish different components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific circumstances.

[0039] The term “including” and its variations used in the present invention are open inclusions, that is, “including but not limited to.” The term “based on” means “based at least in part on.” The term “one embodiment” means “at least one embodiment.”

[0040] It should be noted that the concepts such as "first" and "second" mentioned in the present invention are only used to distinguish the corresponding contents, and are not used to limit the order or interdependence.

[0041] It should be noted that the modifications of "one" and "plurality" mentioned in the present invention are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0042] Figure 1 1 is a schematic flow chart of a method for preparing a TBC battery provided by an embodiment of the present invention. The method for preparing a TBC battery can be applied to the preparation process of a TBC battery. The method for preparing a TBC battery can be used to prepare a TBC battery. Figure 1 As shown, the preparation method comprises:

[0043] S110, forming a mask film layer on the first surface of the N-type silicon substrate; wherein the N-type silicon substrate includes a first surface and a second surface which are opposite to each other, and the first surface is a polished surface, and the second surface is a velvet surface.

[0044] Specifically, an N-type silicon substrate is provided, and the N-type silicon substrate includes a first surface and a second surface that are separated from each other. Exemplarily, the first surface can be understood as the back side of the N-type silicon substrate, and the second surface can be understood as the front side of the N-type silicon substrate. Exemplarily, the first surface and the second surface of the N-type silicon substrate can be rectangular in shape, the long side length of the rectangle can be 183.75 mm, and the short side length of the rectangle can be 182.2 mm.

[0045] The first surface of the N-type silicon substrate is a polished surface. Exemplarily, the first surface of the N-type silicon substrate can be alkali-polished to ensure that the first surface of the N-type silicon substrate is a polished surface, so that the N-type silicon substrate forms a polished surface with high reflectivity, thereby improving the flatness of the battery surface, and increasing the reflection of long-wave light to promote secondary absorption of light, increase short-circuit current and reduce leakage current. Exemplarily, the alkali polishing treatment can use a mixed solution of 38L of concentrated potassium hydroxide (KOH) solution, 10L of additive (BP55), and 460L of pure water. The alkali polishing treatment time can be 280s, and the alkali polishing treatment temperature can be 75°C. Exemplarily, the size of the square of the morphology tested under a microscope on the polished surface is 8-12 microns.

[0046] The second surface of the N-type silicon substrate is a velvet surface. Exemplarily, the second surface of the N-type silicon substrate can be subjected to a velvet treatment so that the second surface of the N-type silicon substrate is a velvet surface. Exemplarily, the velvet surface is a pyramid structure when tested under a microscope. The velvet treatment can remove organic dirt and metal impurities on the surface of the N-type silicon substrate, remove the mechanical damage layer generated by the wire cutting process of the N-type silicon substrate, reduce the recombination center, and form an undulating velvet surface, so as to utilize the light trapping effect, increase the absorption rate of the N-type silicon substrate to sunlight, reduce the reflectivity, and increase the surface area of ​​the N-type silicon substrate, thereby also increasing the PN junction area formed on the surface. Exemplarily, the velvet treatment can use a mixed solution of 36L of concentrated potassium hydroxide (KOH) solution, 8L of velvet additive, and 440L of pure water. The velvet treatment time can be 480s, and the velvet treatment temperature can be 75°C.

[0047] In addition, it should be noted that the present embodiment does not make any specific requirements or special restrictions on the order of the alkali polishing treatment and the texturing treatment. In fact, the alkali polishing treatment can be performed first and then the texturing treatment, or the texturing treatment can be performed first and then the alkali polishing treatment. The present embodiment is only for example and is not limited. In addition, after the alkali polishing treatment and the texturing treatment, the N-type silicon substrate can also be chain pickled with a hydrochloric acid (HCl) solution to further ensure the cleanliness of both sides of the N-type silicon substrate.

[0048] A mask film layer is formed on the first surface of the N-type silicon substrate. For example, a thermal oxidation process, atomic layer deposition (ALD), low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD), coating and other processes can be used to form the mask film layer. This embodiment is only an example and is not limited here.

[0049] S120 , performing laser grooving processing on a side of the mask film layer away from the first surface to form a first region and a second region alternately arranged in an interdigitated shape.

[0050] Specifically, the mask film layer is away from the side of the first surface, that is, the back side of the N-type silicon substrate. The back side of the N-type silicon substrate is laser grooved to form a first area corresponding to the grooved structure and a second area corresponding to the ungrooved structure to expose the second area, that is, to make the position difference between the first area and the second area more obvious. Exemplarily, the laser groove processing can be performed by laser marking using picosecond green light with a laser, with a pulse width of 0.8 picoseconds and a pulse number of 2; the laser marking speed is 42000 mm / minute, the laser power is 28W, and the frequency is 1600Hz. The width of the laser back groove is 300μm and the depth is 1.2 microns.

[0051] In addition, after the laser groove treatment is performed on the side of the mask film layer away from the first surface, the N-type silicon substrate after the laser groove treatment can also be subjected to chain pickling and texturing treatment. Exemplarily, the chain pickling treatment can be used to remove metal impurities such as Al, Fe, Zn, Ni on the surface of the silicon wafer, and to remove metal hydroxides attached to the natural oxide film. Exemplarily, the chain pickling treatment can use a mixed solution of 1.5% hydrochloric acid (HCl) solution and 1.2% hydrofluoric acid (HF) solution. Exemplarily, the groove texturing treatment can be used to effectively remove the impurity cost formed by laser grooves, and effectively form a velvet surface in the groove structure, thereby reducing the surface reflectivity of the TBC battery prepared later. Exemplarily, the groove texturing treatment can use a mixed solution of concentrated potassium hydroxide (KOH) solution and a texturing additive.

[0052] S130, printing borosilicate paste in the first region, and sintering the N-type silicon substrate printed with the borosilicate paste to perform boron diffusion doping on the first region.

[0053] Specifically, it should be noted that in this embodiment, there is no need to feed the N-type silicon substrate into the furnace tube to perform boron diffusion doping treatment on the first region, but to print boron silicon paste in the first region, and to sinter the N-type silicon substrate printed with boron silicon paste to form a boron silicon doping structure in the first region, so that a PN junction is formed in the first region, and the junction process is to generate semiconductor layers of different conductivity types on a piece of semiconductor substrate material. Exemplarily, the square resistance after boron diffusion doping treatment is 280Ω / sq. Exemplarily, the temperature of the sintering process can be 850 degrees Celsius. It can be understood that the present embodiment provides a laser grooving process to form a first region, and prints borosilicate slurry in the first region to perform boron diffusion doping treatment. In this way, the preparation process of the TBC battery can be further simplified. There is no need to use multiple mask processes to perform boron diffusion doping treatment on the first region and phosphorus diffusion doping treatment on the second region respectively. There is also no need to place the N-type silicon substrate in a furnace tube, thereby reducing the use of related equipment. In addition, the borosilicate slurry reacts well with the surface of the N-type silicon substrate, which is more conducive to forming a PN junction of a borosilicate doped structure, and the quality of the PN junction of the formed borosilicate doped structure is better.

[0054] S140, forming a first passivation film layer on a surface of the mask film layer away from the first surface, and performing screen printing and sintering treatment on the first passivation film layer to form an electrode structure to manufacture a TBC battery.

[0055] Specifically, a first passivation film layer is formed on the surface of the mask film layer away from the first surface. For example, atomic layer deposition (ALD), low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD), coating and other processes can be used to form the first passivation film layer on the second surface side of the N-type silicon substrate. It can be understood that the first passivation film layer has passivation and anti-ultraviolet attenuation properties, which can effectively prevent the entire TBC cell from being affected by ultraviolet and infrared, and further ensure the operational reliability of the entire solar cell.

[0056] In a specific embodiment, illustratively, a first passivation film layer can be formed on the first surface of the N-type silicon substrate by a coating process, and the first passivation film layer can further improve the passivation and anti-ultraviolet attenuation performance of the overall TBC battery. Optionally, the material of the first passivation film layer includes silicon nitride. Optionally, the refractive index range of the first passivation film layer is 2.2%-2.3%.

[0057] And, optionally, after printing borosilicate slurry in the first area and sintering the N-type silicon substrate printed with borosilicate slurry to perform boron diffusion doping treatment on the first area, it also includes: forming an anti-ultraviolet attenuation film layer and a second passivation film layer in sequence on the second surface of the N-type silicon substrate. It should be noted that the present embodiment does not make specific requirements and special limitations on the formation order of the first passivation film layer, the anti-ultraviolet attenuation film layer and the second passivation film layer. In fact, the first passivation film layer can be formed first, and then the anti-ultraviolet attenuation film layer and the second passivation film layer can be formed. The anti-ultraviolet attenuation film layer and the second passivation film layer can also be formed first, and then the first passivation film layer can be formed. The preparation process of the first passivation film layer, the anti-ultraviolet attenuation film layer and the second passivation film layer can also be carried out simultaneously. For example, atomic layer deposition (ALD), low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD), coating and other processes can also be used to sequentially form an anti-ultraviolet attenuation film layer and a second passivation film layer on one side of the first surface of the N-type silicon substrate. It can be understood that the anti-ultraviolet attenuation film layer and the second passivation film layer have passivation and anti-ultraviolet attenuation properties, which can effectively prevent the entire TBC cell from being affected by ultraviolet and infrared, and further ensure the operational reliability of the entire solar cell.

[0058] In a specific embodiment, illustratively, an atomic layer deposition (ALD) technique can be used to form an anti-ultraviolet attenuation film layer on the second surface of the N-type silicon substrate. Exemplarily, the temperature of the ALD process can be 200-300°C and the deposition time can be 8-10min. The deposition can be cyclically deposited 20 times under the conditions of a TMA flow rate of 1500sccm, an oxygen flow rate of 1800sccm, and a temperature of 278°C, and the deposition time can be 6min. Optionally, the material of the anti-ultraviolet attenuation film layer includes aluminum oxide. Optionally, the thickness of the anti-ultraviolet attenuation film layer ranges from 6-10nm. Exemplarily, the thickness of the anti-ultraviolet attenuation film layer can be 8nm, which can effectively resist ultraviolet attenuation and passivate the front side of the N-type silicon substrate. Exemplarily, a coating process can be used to form a second passivation film layer on the side of the anti-ultraviolet attenuation film layer away from the second surface. The second passivation film layer can further improve the passivation and anti-ultraviolet attenuation performance of the overall TBC battery, and can also reduce the reflection of sunlight, increase the absorption of sunlight, and improve the photoelectric conversion efficiency of the overall TBC battery. At the same time, it reduces surface recombination, increases the mobility of carriers, and improves the overall performance of the overall TBC battery. Optionally, the material of the second passivation film layer includes silicon nitride. Optionally, the refractive index range of the second passivation film layer is 2.2%-2.3%. In addition, the first passivation film layer and the second passivation film layer can be understood as being prepared at the same time. The first passivation film layer and the second passivation film layer are only different in position, and the rest of the materials, parameters, etc. are the same.

[0059] Furthermore, screen printing is one of the core processes in the manufacturing process of TBC batteries, and is mainly used for electrode formation of TBC batteries. This process uses the basic principle that the mesh holes of the patterned part of the screen are permeable to the slurry, while the mesh holes of the non-patterned part are not permeable to the slurry for printing. During the printing process, the slurry is accurately squeezed onto the N-type silicon substrate through the mesh holes of the screen, and the slurry is evenly distributed on the surface of the TBC battery in the form of a wire to form the required electrode pattern. Generally, the slurry for screen printing may include but is not limited to silver paste. The pattern formed by screen printing includes metal grid lines. High-temperature sintering is used to treat the electrode material screen-printed on the surface of the battery cell at high temperature, dry the slurry on the N-type silicon substrate, burn out the organic components of the slurry, and the slurry can corrode through the passivation film layer and connect to the PN junction, so that the metal grid line forms a good ohmic contact with the N-type silicon substrate, so as to achieve the purpose of collecting and conducting current.

[0060] And, the TBC cell after the screen printing process is sintered at a temperature of 742 degrees Celsius, and then a light injection process is performed. For example, the temperature of the light injection process can be 538°C, and the light intensity can be 5500W / m 2The laser induced process after light injection can induce silver-silicon interdiffusion, thereby significantly reducing contact resistance, increasing the fill factor of the battery, and effectively improving the efficiency of the battery cell. For example, the laser power of the laser induced process can be 18W, and the reverse voltage applied to the battery terminal can be 28V.

[0061] It should also be noted that, after relevant experiments, the TBC battery prepared in this embodiment can be obtained. The open circuit voltage value of the current-voltage characteristic curve test (IV test) of the TBC battery is 740.5mV, the short circuit current value is 13.954A, the filling rate is 85.48%, and the photoelectric conversion efficiency is as high as 26.52%.

[0062] The technical solution in the embodiment of the present invention is that the preparation method first forms a mask film layer on the first surface of an N-type silicon substrate; wherein the N-type silicon substrate includes a first surface and a second surface that are opposite to each other, and the first surface is a polished surface, and the second surface is a velvet surface, and then the side of the mask film layer away from the first surface is laser grooved to form a first area and a second area that are alternately arranged in a forked shape, and then borosilicate slurry is printed in the first area, and the N-type silicon substrate printed with borosilicate slurry is sintered to perform boron diffusion doping treatment on the first area, and finally a first passivation film layer is formed on the surface of the side of the mask film layer away from the first surface, and screen printing and sintering are performed on the first passivation film layer to form an electrode structure to obtain a TBC battery. By using the above method, a laser groove is performed on a side of the mask film layer away from the first surface to form a first region corresponding to the grooved structure and a second region corresponding to the ungrooved structure, and boron diffusion doping is achieved in the first region using borosilicate slurry, and conventional phosphorus diffusion doping is used in the second region, thereby increasing the doping in the first region and reducing the metal composite in the first region. The borosilicate slurry is easier to achieve the boron diffusion effect, and also avoids the formation of aluminum thorns caused by the use of aluminum paste, destroying the PN junction on the N-type silicon wafer, and forming a metal composite region, thereby reducing the contact resistivity of the TBC battery, improving the photoelectric conversion efficiency of the TBC battery, and improving the open circuit voltage value of the TBC battery, thereby solving the problem of low open circuit voltage value and photoelectric conversion efficiency of the existing N-type TBC battery.

[0063] Optionally, after printing borosilicate paste in the first region and sintering the N-type silicon substrate printed with the borosilicate paste to perform boron diffusion doping treatment on the first region, the method further includes: performing oxidation degradation treatment on the sintered N-type silicon substrate.

[0064] Specifically, the oxidation degradation treatment can play a role in high temperature promotion, redistributing the diffused boron, making the boron diffusion in the first region more uniform, and is also similar to making an oxide layer, playing a protective role. Exemplarily, the square resistance after the oxidation degradation treatment is 65Ω / sq.

[0065] In addition, illustratively, after the sintered N-type silicon substrate is subjected to oxidation degradation treatment, the N-type silicon substrate can also be subjected to chain pickling and etching treatment to ensure that both sides of the N-type silicon substrate are clean and free of impurities. Exemplarily, the chain pickling treatment can use a mixed solution of 1.5% hydrochloric acid (HCl) solution and 1.5% hydrofluoric acid (HF) solution. Exemplarily, the etching treatment can use a mixed solution of 28L concentrated potassium hydroxide (KOH) solution, 6L additive (BP63), and 480L pure water, the etching treatment time can be 280s, and the etching treatment temperature can be 72°C.

[0066] Optionally, the mask film layer includes a first mask layer, a second mask layer and a third mask layer; forming the mask film layer on the first surface of the N-type silicon substrate includes: performing thermal oxidation treatment on one side of the first surface of the N-type silicon substrate to form a first mask layer; performing coating treatment on the side of the first mask layer away from the first surface to form a second mask layer; performing thermal oxidation treatment on the side of the second mask layer away from the first surface to form a third mask layer.

[0067] Specifically, the mask film layer includes a first mask layer, a second mask layer and a third mask layer, that is, the mask film layer is a multi-layer structure, which can effectively avoid the subsequent laser grooving process from damaging or damaging the N-type silicon substrate, and the setting of the mask film layer is also conducive to distinguishing the first area from the second area, forming a first area corresponding to the grooved structure and a second area corresponding to the ungrooved structure. Optionally, the material of the first mask layer includes silicon oxide; and / or, the material of the second mask layer includes silicon nitride; and / or, the material of the third mask layer includes silicon oxide. That is, by adopting a thermal oxidation process, oxygen reacts with silicon atoms to form a corresponding silicon oxide layer. In addition, the mask film layer may also include a fourth mask layer, which is located on one side of the second surface of the N-type silicon substrate, and the fourth mask layer can protect the second surface of the N-type silicon substrate, and prevent the subsequent etching or pickling or alkali polishing from damaging or damaging the second surface of the N-type silicon substrate. Optionally, the material of the fourth mask layer includes silicon oxide. That is, by using a thermal oxygen process, oxygen reacts with silicon atoms to form a corresponding silicon oxide layer.

[0068] Figure 2 1 is a flow chart of another method for preparing a TBC battery provided by an embodiment of the present invention. This embodiment is optimized on the basis of the above embodiment. Optionally, before forming a mask film layer on the first surface of the N-type silicon substrate, it also includes:

[0069] Forming a passivation contact film layer on the first surface of the N-type silicon substrate, and performing phosphorus diffusion doping treatment on a side of the passivation contact film layer away from the first surface;

[0070] Forming a mask film layer on the first surface of the N-type silicon substrate, comprising:

[0071] forming a mask film layer on a surface of the passivation contact film layer away from the first surface;

[0072] Laser grooving is performed on a side of the mask film layer away from the first surface to form a first region and a second region alternately arranged in an interdigitated shape, including:

[0073] Laser grooving is performed on a side of the mask film layer corresponding to the first region away from the first surface, so that the bottom of the grooving structure corresponding to the first region is located in the passivation contact film layer.

[0074] For details not yet provided in this embodiment, please refer to the above embodiments. Figure 2 As shown, the preparation method comprises:

[0075] S210, forming a passivation contact film layer on the first surface of the N-type silicon substrate, and performing phosphorus diffusion doping treatment on a side of the passivation contact film layer away from the first surface.

[0076] Specifically, the passivation contact film layer includes a tunneling oxide layer and a polysilicon layer, and the passivation contact film layer is formed on the first surface of the N-type silicon substrate, that is, the tunneling oxide layer and the polysilicon layer are sequentially formed on the first surface of the N-type silicon substrate. Among them, the tunneling oxide layer and the polysilicon layer are used to allow the majority carriers (electrons) to pass smoothly through the tunneling effect, while preventing the recombination of minority carriers (holes) to achieve selective collection of carriers, reduce surface recombination, and improve the open circuit voltage and fill factor of the battery, thereby improving the photoelectric conversion efficiency of the overall solar cell. The composite layer of the tunneling oxide layer and the polysilicon layer together forms a passivation contact structure, which can effectively reduce the surface recombination and metal contact recombination of the overall solar cell. In other words, depositing an ultra-thin tunneling oxide layer on the first surface of the N-type silicon substrate can provide good interface passivation and provide different carrier tunneling barriers. Depositing a polysilicon layer on the tunneling oxide layer can increase the migration rate of electrons and suppress the migration rate of holes. In addition, the polysilicon layer contacts the subsequent metal electrode and acts as an electron transmission bridge. For example, low pressure chemical vapor deposition (LPCVD) technology can be used to first prepare an ultra-thin silicon dioxide layer on the first surface of the N-type silicon substrate as the above-mentioned tunneling oxide layer, and then deposit a polycrystalline silicon thin layer on the ultra-thin silicon dioxide layer to form a polycrystalline silicon layer that meets the passivation effect.

[0077] After forming a passivation contact film layer on the first surface of the N-type silicon substrate, a phosphorus diffusion doping treatment can be performed on the side of the passivation contact film layer away from the first surface to form a PN junction on the first surface of the N-type silicon substrate. The junction making process is to generate semiconductor layers of different conductivity types on a piece of semiconductor base material. Exemplarily, the square resistance after the phosphorus diffusion doping treatment is 42Ω / sq, and the junction depth of the ECV is 1.08μm.

[0078] S220, forming a mask film layer on a surface of the passivation contact film layer away from the first surface.

[0079] Specifically, a mask film layer is formed on a side surface of the passivation contact film layer away from the first surface. For example, a thermal oxidation process, atomic layer deposition (ALD), low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD), coating and other processes can be used to form the mask film layer. This embodiment is only an example and is not limited here.

[0080] S230, performing a laser groove process on a side of the mask film layer corresponding to the first region away from the first surface, so that the bottom of the groove structure corresponding to the first region is located in the passivation contact film layer.

[0081] Specifically, the back side of the N-type silicon substrate is subjected to laser grooving to form a first region corresponding to the grooved structure and a second region corresponding to the ungrooved structure to expose the second region, that is, to make the position difference between the first region and the second region more obvious. It should be noted that after the laser grooving, the bottom of the grooved structure corresponding to the first region is located in the passivation contact film layer, that is, for any first region, the laser grooving process is to remove the corresponding mask film layer and the phosphorus-doped silicon-doped structure treated with phosphorus diffusion doping. Exemplarily, the depth of the laser grooving process is 1.2μm, while the junction depth of the ECV treated with phosphorus diffusion doping is 1.08μm, so that the laser grooving process can completely remove the corresponding mask film layer and the phosphorus-doped silicon-doped structure treated with phosphorus diffusion doping.

[0082] Furthermore, the first surface of the N-type silicon substrate is formed with a first region and a second region arranged alternately in a finger-like shape. Exemplarily, the first region may be a P region, and the second region may be an N region. After the above-mentioned preparation process, the second region includes a phosphorus silicon doped structure treated with phosphorus diffusion doping, and a TOPcon structure (tunneling oxide layer passivation contact) is also added. Subsequently, the first region includes a boron silicon doped structure treated with boron diffusion doping, and the TOPcon structure (tunneling oxide layer passivation contact) is also retained.

[0083] S240, printing borosilicate paste in the first region, and sintering the N-type silicon substrate printed with the borosilicate paste to perform boron diffusion doping on the first region.

[0084] S250, forming a first passivation film layer on a surface of the mask film layer away from the first surface, and performing screen printing and sintering treatment on the first passivation film layer to form an electrode structure to manufacture a TBC battery.

[0085] Figure 3 1 is a schematic flow chart of another method for preparing a TBC battery provided by an embodiment of the present invention. This embodiment is optimized on the basis of the above embodiment. Optionally, screen printing and sintering are performed on the first passivation film layer to form an electrode structure to prepare a TBC battery, including:

[0086] Printing silver paste on the first passivation film layer corresponding to the first area and the first passivation film layer corresponding to the second area respectively;

[0087] The N-type silicon substrate printed with silver paste is sintered to form a first metal gate line contacting the first area and a second metal gate line contacting the second area respectively.

[0088] For details not yet provided in this embodiment, please refer to the above embodiments. Figure 3 As shown, the preparation method comprises:

[0089] S310, forming a mask film layer on the first surface of the N-type silicon substrate; wherein the N-type silicon substrate includes a first surface and a second surface which are opposite to each other, and the first surface is a polished surface, and the second surface is a velvet surface.

[0090] S320, performing laser grooving processing on a side of the mask film layer away from the first surface to form a first region and a second region alternately arranged in an interdigitated shape.

[0091] S330, printing borosilicate paste in the first region, and sintering the N-type silicon substrate printed with the borosilicate paste to perform boron diffusion doping on the first region.

[0092] S340, forming a first passivation film layer on a surface of the mask film layer away from the first surface, and printing silver paste on the first passivation film layer corresponding to the first area and the first passivation film layer corresponding to the second area respectively.

[0093] Specifically, the type of silver paste printed on the first passivation film layer corresponding to the first region and the type of silver paste printed on the first passivation film layer corresponding to the second region can be the same or different, and can be determined specifically according to the requirements of the corresponding metal grid lines to be formed. For example, the silver paste printed on the first passivation film layer corresponding to the first region can be aluminum-free silver paste, and the silver paste printed on the first passivation film layer corresponding to the second region can be conventional silver paste. In this way, the passivation of the first region is increased, and the doping effect of the first region is added, so that the photoelectric conversion efficiency of the prepared TBC battery can be improved, and the open circuit voltage value of the TBC battery can be increased. For example, a screen / mask with a customized pattern can be used to distinguish the first region and the second region. If the opening area of ​​the screen / mask with the customized pattern corresponds to the first region, the silver paste can be printed on the first passivation film layer corresponding to the first region. If the opening area of ​​the screen / mask with the customized pattern corresponds to the second region, the silver paste can be printed on the first passivation film layer corresponding to the second region.

[0094] S350, sintering the N-type silicon substrate printed with the silver paste to form a first metal gate line contacting the first region and a second metal gate line contacting the second region respectively.

[0095] The first surface of the N-type silicon substrate is formed with a first region and a second region arranged alternately in an interdigitated shape. Exemplarily, the first region may be a P region, and the second region may be an N region. Specifically, a first metal gate line in contact with the first region is formed on the first surface of the N-type silicon substrate. Exemplarily, the first metal gate line may be a positive gate line, that is, to achieve conduction between the p+ doped region and the positive gate line. A second metal gate line in contact with the second region is formed on the first surface of the N-type silicon substrate. Exemplarily, the second metal gate line may be a negative gate line, that is, to achieve conduction between the n+ doped region and the negative gate line.

[0096] Based on the same inventive concept, an embodiment of the present invention further provides a TBC battery. The TBC battery is prepared by a TBC battery preparation method provided in any one of the embodiments of the present invention. Therefore, the TBC battery has the functional modules and beneficial effects corresponding to the TBC battery preparation method.

[0097] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for preparing a TBC battery, characterized in that: include: Forming a mask film layer on the first surface of the N-type silicon substrate; wherein the N-type silicon substrate comprises the first surface and the second surface which are opposite to each other, and the first surface is a polished surface, and the second surface is a velvet surface; Performing a laser grooving process on a side of the mask film layer away from the first surface to form a first region and a second region alternately arranged in an interdigitated shape; Printing borosilicate paste in the first region, and sintering the N-type silicon substrate printed with the borosilicate paste to perform boron diffusion doping on the first region; A first passivation film layer is formed on a surface of the mask film layer away from the first surface, and screen printing and sintering are performed on the first passivation film layer to form an electrode structure, thereby manufacturing the TBC battery.

2. The preparation method according to claim 1, characterized in that: After printing borosilicate paste in the first region and sintering the N-type silicon substrate printed with the borosilicate paste to perform boron diffusion doping on the first region, the method further includes: The N-type silicon substrate after sintering is subjected to oxidation degradation treatment.

3. The preparation method according to claim 1, characterized in that: Before forming a mask film layer on the first surface of the N-type silicon substrate, the method further includes: forming a passivation contact film layer on the first surface of the N-type silicon substrate, and performing a phosphorus diffusion doping process on a side of the passivation contact film layer away from the first surface; Forming a mask film layer on the first surface of the N-type silicon substrate, comprising: forming the mask film layer on a surface of the passivation contact film layer away from the first surface; Laser grooving is performed on a side of the mask film layer away from the first surface to form first and second regions alternately arranged in an interdigitated manner, including: A laser groove process is performed on a side of the mask film layer corresponding to the first region away from the first surface, so that the bottom of the groove structure corresponding to the first region is located in the passivation contact film layer.

4. The preparation method according to claim 1, characterized in that: Screen printing and sintering are performed on the first passivation film layer to form an electrode structure to obtain the TBC battery, comprising: Printing silver paste on the first passivation film layer corresponding to the first region and on the first passivation film layer corresponding to the second region respectively; The N-type silicon substrate printed with the silver paste is sintered to form a first metal gate line in contact with the first region and a second metal gate line in contact with the second region.

5. The preparation method according to claim 4, characterized in that: The material of the first passivation film layer includes silicon nitride.

6. The preparation method according to claim 1, characterized in that: After printing borosilicate paste in the first region and sintering the N-type silicon substrate printed with the borosilicate paste to perform boron diffusion doping on the first region, the method further includes: An anti-ultraviolet attenuation film layer and a second passivation film layer are sequentially formed on the second surface of the N-type silicon substrate.

7. The preparation method according to claim 6, characterized in that: The material of the anti-ultraviolet attenuation film layer includes aluminum oxide; and / or the material of the second passivation film layer includes silicon nitride.

8. The preparation method according to claim 1, characterized in that: The mask film layer comprises a first mask layer, a second mask layer and a third mask layer; Forming a mask film layer on the first surface of the N-type silicon substrate, comprising: Performing thermal oxidation treatment on one side of the first surface of the N-type silicon substrate to form the first mask layer; Performing a coating process on a side of the first mask layer away from the first surface to form the second mask layer; A thermal oxidation treatment is performed on a side of the second mask layer away from the first surface to form the third mask layer.

9. The preparation method according to claim 8, characterized in that: The material of the first mask layer includes silicon oxide; and / or, the material of the second mask layer includes silicon nitride; and / or, the material of the third mask layer includes silicon oxide.

10. A TBC battery, characterized in that: The TBC battery is prepared by the preparation method of any one of claims 1 to 9.

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