Laser etching method, preparation method of solar cell and solar cell
By using laser etching methods with opposite directions twice during laser etching, the problem of etching unevenness caused by dust interference in traditional laser etching is solved, and better etching uniformity and alkaline solution etching effect are achieved.
Patent Information
- Application Number
- CN202410173999.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-06
- Publication Date
- 2025-08-12
AI Technical Summary
In traditional laser etching methods, the interference effect of dust substances leads to uneven etching effects, which affects the effect of subsequent alkaline solution etching.
The laser etching method with opposite directions is adopted, first laser etching is performed in the first direction, and then laser etching is performed in the second direction opposite to the first direction, forming a complementary effect to improve etching uniformity.
The uniformity of laser etching is improved, the residue after etching is reduced, and the effect of alkaline solution etching is improved.
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Figure CN120460906A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of photovoltaic technology, and in particular to a laser etching method, a method for preparing a solar cell, and a solar cell. Background Art
[0002] In the solar cell manufacturing process, lasers are often used to pattern the cells. During the production process, lasers are typically used to remove oxides deposited on the surface of doped silicon, followed by etching with an alkaline solution to form grooves of a certain depth. When the protective layer is removed by laser, the laser melts or vaporizes the silicon material layer beneath the protective layer, generating a large amount of dust. In traditional laser etching methods, dust can affect the laser's etching effect on solar cells, resulting in poor laser etching uniformity, which in turn affects the subsequent alkaline solution etching effect. Summary of the Invention
[0003] Based on this, it is necessary to provide a laser etching method, a method for preparing a solar cell, and a solar cell. The laser etching method of the present application can achieve good laser etching uniformity.
[0004] In a first aspect, the present application provides a laser etching method, comprising the following steps:
[0005] A substrate is provided, wherein a first silicon material layer is provided on a surface of the substrate, a protective layer is provided on a surface of the first silicon material layer away from the substrate, and the protective layer has a predetermined area on a surface away from the substrate;
[0006] Performing first laser etching in the preset area along a first direction;
[0007] Performing second laser etching in the preset area along a second direction, wherein the second direction is opposite to the first direction;
[0008] An etched area is formed in the predetermined area.
[0009] In some embodiments, the material of the protection layer includes at least one of nitride and oxide.
[0010] In some embodiments, the material of the first silicon material layer is selected from at least one of doped or undoped amorphous silicon, doped or undoped single crystal silicon, and doped or undoped polycrystalline silicon.
[0011] In some embodiments, the first laser etching includes multiple first sub-etchings, the displacement of the laser along the first direction in each first sub-etching is a first preset displacement, and the distance between the starting points of two adjacent first sub-etchings is 20% to 200% of the first preset displacement.
[0012] In some embodiments, the second laser etching includes multiple second sub-etchings, the displacement of the laser along the second direction in each second sub-etching is a second preset displacement, and the distance between the starting points of two adjacent second sub-etchings is 20% to 200% of the second preset displacement.
[0013] In some embodiments, the distance between the starting points of two adjacent first sub-etchings is 20% to 100% of the first preset displacement, and the distance between the starting points of two adjacent second sub-etchings is 20% to 100% of the second preset displacement.
[0014] In some embodiments, the energy of the first laser etching is 0.1 J / cm 2 ~0.4J / cm 2 .
[0015] In some embodiments, the energy of the second laser etching is 0.1 J / cm 2 ~0.4J / cm 2 .
[0016] In some embodiments, the distance between the starting points of two adjacent first sub-etchings is greater than the first preset displacement and less than or equal to 200% of the first preset distance, the distance between the starting points of two adjacent second sub-etchings is greater than the second preset displacement and less than or equal to 200% of the second preset distance, and the etching area of the second sub-etching covers the gap between adjacent first sub-etchings.
[0017] In some embodiments, the energy of the first laser etching is greater than 0.4 J / cm 2 and less than or equal to 0.8J / cm 2 .
[0018] In some embodiments, the energy of the second laser etching is greater than 0.4 J / cm 2 and less than or equal to 0.8J / cm 2 .
[0019] In a second aspect, the present application provides a method for preparing a solar cell, comprising the following steps:
[0020] The protective layer is etched using any of the laser etching methods described above to obtain the etched area.
[0021] In some embodiments, after obtaining the etched area, the following steps are further included:
[0022] performing wet etching on the etching area;
[0023] A second silicon material layer is prepared in the etched area after wet etching, wherein the first silicon material layer includes a first doping element, and the second silicon material layer includes a second doping element. The doping types of the first doping element and the second doping element are opposite, and there is a gap between the second silicon material layer and the first silicon material layer.
[0024] In a third aspect, the present application provides a solar cell prepared by any of the above-mentioned methods for preparing a solar cell.
[0025] In the above-mentioned laser etching method, by performing two laser etchings in opposite directions on a preset area, the influence of dust on the laser etching effect in a single laser etching in a single direction in the traditional laser etching method can be reduced. During the process of performing the first laser etching along the first direction on the preset area, as the laser etches the sample along its direction of movement, the dust generated gradually increases. The dust will interfere with the laser, causing the energy distribution of the laser to change. As the etching process progresses, the subsequent laser etching effect on the sample gradually weakens. By performing the second laser etching on the preset area in a second direction opposite to the first direction, the two laser etchings in different directions can form a complementary effect, so that the etching effect at each location in the preset area is of equal strength, thereby achieving better laser etching uniformity. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 Schematic diagram of the etching effect in the traditional laser etching method;
[0027] Figure 2 This is an optical microscope image of the sample surface after etching using the traditional laser etching method;
[0028] Figure 3 for Figure 2 A local scanning electron microscope image of the etched area on the sample surface after etching using the traditional laser etching method;
[0029] Figure 4 for Figure 2 Optical microscope image of the sample surface after being etched by alkaline solution in the traditional laser etching method;
[0030] Figure 5 A schematic diagram illustrating the etching effect of the etching method provided in one embodiment of the present application;
[0031] Figure 6 An optical microscope image of the sample surface after etching by the etching method provided in one embodiment of the present application;
[0032] Figure 7 A local scanning electron microscope image of the etched area on the sample surface after etching by the etching method provided in one embodiment of the present application;
[0033] Figure 8 This is an optical microscope image of the sample surface etched by the etching method provided in one embodiment of the present application and then etched with an alkaline solution;
[0034] Figure 9 A schematic diagram of an etching method provided in yet another embodiment of the present application;
[0035] Figure 10 This is an optical microscope image of the sample surface after the first laser etching by the etching method provided in Example 1 of the present application;
[0036] Figure 11 This is an optical microscope image of the sample surface after the first laser etching by the etching method provided in Example 2 of the present application;
[0037] Figure 12 This is an optical microscope image of the sample surface after the first laser etching by the etching method provided in Example 3 of the present application;
[0038] Figure 13 This is an optical microscope image of the sample surface after etching using the etching method provided in Example 3 of the present application;
[0039] Figure 14 This is an optical microscope image of the etched sample surface provided in Example 3 of the present application after being etched with an alkaline solution;
[0040] Figure 15 This is an optical microscope image of the sample surface after etching by the etching method provided in Comparative Example 1 of the present application, wherein Figure 15 (a) is Figure 15 A partial enlarged schematic diagram of (b);
[0041] Figure 16 This is an optical microscope image of the etched sample surface provided in Comparative Example 1 of the present application after being etched with an alkaline solution. DETAILED DESCRIPTION
[0042] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.
[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0044] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.
[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.
[0046] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.
[0047] Reference Figure 1 As shown, Figure 1It is a schematic diagram of the etching effect in the traditional laser etching method. In which, on each area to be etched, the laser is used to perform a single etching on the area to be etched in the direction indicated by the arrow. For example, the uppermost area to be etched in the sample is etched from left to right by the laser, and then the laser etches the second upper etched area from right to left. The middle position of the area to be etched is a spacing area that does not need to be etched, and the same is true in the following schematic diagrams. It can be seen that in each area to be etched, the etching effect gradually weakens along the etching direction of the laser. It was found in the present application that this is because, as the laser etches the sample along its movement direction, the dust generated gradually increases, and the dust will interfere with the laser, causing the energy distribution of the laser to change, and then as the etching process proceeds, the subsequent laser etching effect on the sample gradually weakens, resulting in poor uniformity of the etching effect on the area to be etched.
[0048] It should be noted that, in this application, it was found that since the energy absorption capacity of the protective layer is less than that of the silicon material layer below it, when the protective layer is laser etched, the silicon material layer below the protective layer will absorb more energy and melt before the protective layer. The melting of the lower silicon material layer first will cause the interface of the protective layer to expand, and then the protective layer on the surface will break to produce dust. As the laser continues to etch in the same direction, the dust will gradually increase, causing interference with the laser, resulting in the laser etching effect on the sample gradually deteriorating in the later stage of etching.
[0049] Reference Figure 2~Figure 3 As shown, Figure 2 This is an optical microscope image of the sample surface after etching using the traditional laser etching method, where: Figure 2 The etching direction is from bottom to top. Figure 3 for Figure 2 Local scanning electron microscope image of the . Figure 2 The dotted box is the area etched by the traditional laser etching method. It can be seen that the flatness of the sample surface gradually deteriorates along the etching direction in this area. Figure 3 It can be seen that the flatness of the sample surface in the etched area is poor after etching. Figure 4 As shown, Figure 4 for Figure 2 The optical microscope image of the sample surface after being etched by alkaline solution in the traditional laser etching method. It can be seen that due to the poor etching uniformity of the traditional laser etching method, more oxide residues are left, which in turn leads to poor etching effect of alkaline solution. Figure 4 There are many spot-like residues in the area after alkaline solution etching on the surface of the sample.
[0050] In order to solve the above problem, an embodiment of the present application provides a laser etching method, comprising the following steps:
[0051] S100: providing a substrate, wherein a first silicon material layer is disposed on a surface of the substrate, a protective layer is disposed on a surface of the first silicon material layer away from the substrate, and the surface of the protective layer away from the substrate has a predetermined area;
[0052] S200: performing first laser etching in a preset area along a first direction;
[0053] S300: performing second laser etching in a preset area along a second direction, where the second direction is opposite to the first direction; and forming an etching area in the preset area.
[0054] In the above-mentioned laser etching method, by performing two laser etchings in opposite directions on a predetermined area, the influence of dust on the laser etching effect in a single, single-direction laser etching in conventional laser etching methods can be reduced. During the first laser etching process along a first direction in the predetermined area, as the laser etches the sample along its direction of motion, the generated dust gradually increases. The dust interferes with the laser, causing the energy distribution of the laser to change, and thus, as the etching process proceeds, the subsequent laser etching effect on the sample gradually weakens. By performing a second laser etching on the predetermined area along a second direction opposite to the first direction, the two laser etchings in different directions can form a complementary effect, so that the etching effect at various locations within the predetermined area is of equal strength, thereby achieving better laser etching uniformity.
[0055] Reference Figure 5 As shown, Figure 5 This is a schematic diagram of the effect of laser etching in the method for preparing a solar cell provided in one embodiment of the present application. For example, Figure 5 In the process, each preset area is subjected to two first laser etchings and second laser etchings in opposite directions. Specifically, the top preset area in the sample is first subjected to the first laser etching from left to right, and then the second laser etching is performed from right to left. The subsequent preset areas are etched in the same way as the top preset area. It can be seen that in each preset area, after the first laser etching and the second laser etching in opposite directions, an etching effect with good etching uniformity can be obtained. Further, referring to Figure 6 and Figure 7 As shown, Figure 6 This is an optical microscope image of the sample surface after etching by the etching method provided in one embodiment of the present application, wherein: Figure 7 for Figure 6 It can be seen from the local scanning electron microscope image of the etched area on the sample surface that compared with the traditional laser etching method, the laser etching method of the present application can obtain an etching effect with higher surface flatness, less residue, and better etching uniformity. Figure 8 As shown, Figure 8 for Figure 6 The optical microscope image of the sample surface after being etched with alkaline solution. It can be seen that the laser etching method of the present application has good etching uniformity and less residue, which can make the alkaline solution etching effect better. Figure 8 There is less residue in the area after alkaline solution etching on the surface of the sample.
[0056] In some embodiments, the material of the protection layer includes at least one of nitride and oxide.
[0057] In some embodiments, the material of the first silicon material layer is selected from at least one of doped or undoped amorphous silicon, doped or undoped single crystal silicon, and doped or undoped polysilicon.
[0058] In some embodiments, the protective layer includes at least one of silicon oxide or silicon nitride.
[0059] Reference Figure 9 As shown, in some embodiments, the first laser etching includes multiple first sub-etchings, the displacement of the laser along the first direction in each first sub-etching is a first preset displacement, and the distance between the starting points of two adjacent first sub-etchings is 20% to 200% of the first preset displacement.
[0060] It should be noted that the first laser etching comprises multiple first sub-etches, and the displacement of the laser in the first direction during each first sub-etch is the first preset displacement. This means that the first laser etching is performed using a pulsed laser. During each first sub-etch, the laser is active and advances a distance in the first direction, which is the first preset displacement. Between each first sub-etch, the laser stops and moves to the starting position of the next first sub-etch.
[0061] It is understandable that Figure 9 Only the etching effect diagram of the first sub-etching on the preset area is shown, and Figure 9 The distance between the starting points of two adjacent first sub-etches is 200% of the first preset displacement. When the distance between the starting points of two adjacent first sub-etches is greater than 20% of the first preset displacement and less than 100% of the first preset displacement, the etching areas of each two adjacent first sub-etches partially overlap. When the distance between the starting points of two adjacent first sub-etches is 100% of the first preset displacement, the etching areas of each two adjacent first sub-etches are continuous. When the distance between the starting points of two adjacent first sub-etches is greater than 100% of the first preset displacement and less than or equal to 200% of the first preset displacement, there is a gap between the etching areas of each two adjacent first sub-etches.
[0062] Optionally, the distance between the starting points of two adjacent first sub-etches is 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 105%, 110%, 115%, 120%, 125%, 130%, 135%, 140%, 145%, 150%, 155%, 160%, 165%, 170%, 175%, 180%, 185%, 190%, 195%, or 200% of the first preset displacement. Alternatively, the percentage of the distance between the starting points of two adjacent first sub-etches to the first preset displacement may also be within a range between any two of the above percentages.
[0063] In some embodiments, the second laser etching includes multiple second sub-etchings, the displacement of the laser along the second direction in each second sub-etching is a second preset displacement, and the distance between the starting points of two adjacent second sub-etchings is 20% to 200% of the second preset displacement.
[0064] It should be noted that the second laser etching comprises multiple second sub-etches, and the displacement of the laser in the second direction during each second sub-etch is the second preset displacement. This means that the second laser etching is performed using a pulsed laser. During each second sub-etch, the laser is active and advances a distance in the second direction, which is the second preset displacement. Between each second sub-etch, the laser stops and moves to the starting position of the next second sub-etch.
[0065] It can be understood that when the distance between the starting points of two adjacent second sub-etches is greater than 20% and less than 100% of the second preset displacement, the etched areas of each two adjacent second sub-etches partially overlap. When the distance between the starting points of two adjacent second sub-etches is 100% of the second preset displacement, the etched areas of each two adjacent second sub-etches are continuous. When the distance between the starting points of two adjacent second sub-etches is greater than 100% of the second preset displacement and less than or equal to 200% of the second preset displacement, there is a gap between the etched areas of each two adjacent second sub-etches.
[0066] Optionally, the distance between the starting points of two adjacent second sub-etches is 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 105%, 110%, 115%, 120%, 125%, 130%, 135%, 140%, 145%, 150%, 155%, 160%, 165%, 170%, 175%, 180%, 185%, 190%, 195%, or 200% of the second preset displacement. Alternatively, the percentage of the distance between the starting points of two adjacent second sub-etches to the second preset displacement may also be within a range between any two of the above percentages.
[0067] In some embodiments, the first preset distance and the second preset distance are equal. The first preset distance and the second preset distance are equal to facilitate the etching operation.
[0068] In some embodiments, the distance between the starting points of two adjacent first sub-etches is equal to the distance between the starting points of two adjacent second sub-etches. The distance between the starting points of two adjacent first sub-etches is equal to the distance between the starting points of two adjacent second sub-etches, which facilitates the etching operation.
[0069] In some embodiments, the distance between the starting points of two adjacent first sub-etchings is 20% to 100% of the first preset displacement, and the distance between the starting points of two adjacent second sub-etchings is 20% to 100% of the second preset displacement.
[0070] In some embodiments, the energy of the first laser etching is 0.1 J / cm 2 ~0.4J / cm 2 When the distance between the starting points of two adjacent first sub-etchings is 20% to 100% of the first preset displacement, the energy of the first laser etching is set within a smaller range. Within the energy range of the first laser etching, the etching effect is better. Optionally, the energy of the first laser etching is 0.1 J / cm 2 , 0.12J / cm 2 , 0.14J / cm 2 , 0.16J / cm 2 , 0.18J / cm 2 , 0.2J / cm 2 , 0.22J / cm 2 , 0.24J / cm 2 , 0.26J / cm 2 , 0.28J / cm 2 , 0.3J / cm 2 , 0.32J / cm 2 , 0.34J / cm2 , 0.36J / cm 2 , 0.38J / cm 2 or 0.4 J / cm 2 Alternatively, the energy of the first laser etching may also be within the range between any two of the above energies.
[0071] In some embodiments, the energy of the second laser etching is 0.1 J / cm 2 ~0.4J / cm 2 When the distance between the starting points of two adjacent second sub-etchings is 20% to 100% of the second preset displacement, the energy of the second laser etching is set within a smaller range. Within the energy range of the second laser etching, the etching effect is better. Optionally, the energy of the second laser etching is 0.1 J / cm 2 , 0.12J / cm 2 , 0.14J / cm 2 , 0.16J / cm 2 , 0.18J / cm 2 , 0.2J / cm 2 , 0.22J / cm 2 , 0.24J / cm 2 , 0.26J / cm 2 , 0.28J / cm 2 , 0.3J / cm 2 , 0.32J / cm 2 , 0.34J / cm 2 , 0.36J / cm 2 , 0.38J / cm 2 or 0.4 J / cm 2 Alternatively, the energy of the second laser etching may also be within the range between any two of the above energies.
[0072] In some embodiments, the distance between the starting points of two adjacent first sub-etchings is greater than the first preset displacement and less than or equal to 200% of the first preset distance, the distance between the starting points of two adjacent second sub-etchings is greater than the second preset displacement and less than or equal to 200% of the second preset distance, and the etching area of the second sub-etching covers the gap between adjacent first sub-etchings.
[0073] The distance between the starting points of two adjacent first sub-etchings is greater than the first preset displacement and less than or equal to 200% of the first preset distance, that is, there is a gap between the etching areas of the two adjacent first sub-etchings, that is, after the previous first sub-etching is completed, the laser stops working and continues to move forward a distance in the first direction before performing the next first sub-etching. When there is a gap between the etching areas of two adjacent first sub-etchings, the influence of the dust generated during the previous first sub-etching on the subsequent first sub-etching can be reduced, and the etching effect of the first laser etching can be better. Similarly, the distance between the starting points of two adjacent second sub-etchings is greater than the second preset displacement and less than or equal to 200% of the second preset distance, which can make the etching effect of the second laser etching better. At the same time, the etching area of the second sub-etching covers the gap between the adjacent first sub-etchings, so that the first laser sub-etching and the second laser sub-etching can form a continuous etching area.
[0074] In some embodiments, the energy of the first laser etching is greater than 0.4 J / cm 2 and less than or equal to 0.8J / cm 2 When the distance between the starting points of two adjacent first sub-etchings is greater than the first preset displacement and less than or equal to 200% of the first preset distance, and the distance between the starting points of two adjacent second sub-etchings is greater than the second preset displacement and less than or equal to 200% of the second preset distance, the energy of the first laser etching is set within the above range, and the etching effect is better. Optionally, the energy of the first laser etching is 0.4 J / cm 2 , 0.42J / cm 2 , 0.44J / cm 2 , 0.46J / cm 2 , 0.48J / cm 2 , 0.51J / cm 2 , 0.52J / cm 2 , 0.54J / cm 2 , 0.56J / cm 2 , 0.58J / cm 2 , 0.6J / cm 2 , 0.62J / cm 2 , 0.64J / cm 2 , 0.66J / cm 2 , 0.68J / cm 2 , 0.7J / cm 2 , 0.72J / cm 2 , 0.74J / cm 2 , 0.76J / cm 2 , 0.78J / cm 2 or 0.8 J / cm 2Alternatively, the energy of the first laser etching may also be within the range between any two of the above energies.
[0075] In some embodiments, the energy of the second laser etching is greater than 0.4 J / cm 2 and less than or equal to 0.8J / cm 2 When the distance between the starting points of two adjacent first sub-etchings is greater than the first preset displacement and less than or equal to 200% of the first preset distance, and the distance between the starting points of two adjacent second sub-etchings is greater than the second preset displacement and less than or equal to 200% of the second preset distance, the energy of the second laser etching is set within the above range, and the etching effect is better. Optionally, the energy of the second laser etching is 0.4 J / cm 2 , 0.42J / cm 2 , 0.44J / cm 2 , 0.46J / cm 2 , 0.48J / cm 2 , 0.51J / cm 2 , 0.52J / cm 2 , 0.54J / cm 2 , 0.56J / cm 2 , 0.58J / cm 2 , 0.6J / cm 2 , 0.62J / cm 2 , 0.64J / cm 2 , 0.66J / cm 2 , 0.68J / cm 2 , 0.7J / cm 2 , 0.72J / cm 2 , 0.74J / cm 2 , 0.76J / cm 2 , 0.78J / cm 2 or 0.8 J / cm 2 Alternatively, the energy of the second laser etching may also be within the range between any two of the above energies.
[0076] In some embodiments, the first silicon material layer includes a phosphorus-doped silicon material layer or a boron-doped silicon material layer.
[0077] In some embodiments, the first silicon material layer includes a silicon oxide layer, and the silicon oxide layer is located on a surface of the phosphorus-doped silicon material layer or the boron-doped silicon material layer away from the substrate.
[0078] In some embodiments, the thickness of the phosphorus-doped silicon material layer or the boron-doped silicon material layer is 100 nm to 300 nm. Alternatively, the thickness of the phosphorus-doped silicon material layer or the boron-doped silicon material layer is 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, or 300 nm. Alternatively, the thickness of the phosphorus-doped silicon material layer or the boron-doped silicon material layer may also be within a range between any two of the aforementioned thicknesses.
[0079] In some embodiments, the thickness of the silicon oxide layer is 10 nm to 100 nm. Alternatively, the thickness of the silicon oxide layer is 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, or 100 nm. Alternatively, the thickness of the silicon oxide layer may be within a range between any two of the aforementioned thicknesses.
[0080] Another embodiment of the present application provides a method for preparing a solar cell, comprising the following steps:
[0081] The protective layer is etched using any of the above laser etching methods to obtain an etched area.
[0082] In some embodiments, after obtaining the etched area, the following steps are further included:
[0083] performing wet etching on the etched area;
[0084] A second silicon material layer is prepared in the etched area after wet etching, wherein the first silicon material layer includes a first doping element, and the second silicon material layer includes a second doping element. The doping types of the first doping element and the second doping element are opposite, and there is a gap between the second silicon material layer and the first silicon material layer.
[0085] In some embodiments, the wet etching includes alkaline etching.
[0086] In some embodiments, the alkaline solution includes at least one of a NaOH solution and a KOH solution.
[0087] In some embodiments, the mass concentration of the alkali solution is 1% to 20%. Alternatively, the mass concentration of the alkali solution is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%. Alternatively, the mass concentration of the alkali solution may be within a range between any two of the above concentrations.
[0088] Yet another embodiment of the present application provides a solar cell, which is prepared by any of the above-mentioned methods for preparing a solar cell.
[0089] The following are specific embodiments
[0090] Example 1
[0091] Laser etching:
[0092] (1) Providing a substrate, wherein a first silicon material layer is provided on a surface of the substrate, a protective layer is provided on a surface of the first silicon material layer away from the substrate, and the protective layer has a predetermined area on the surface away from the substrate;
[0093] (2) performing first laser etching in a preset area along a first direction, the first laser etching including multiple first sub-etchings, the displacement of the laser along the first direction in each first sub-etching being a first preset displacement, and the distance between the starting points of two adjacent first sub-etchings being 100% of the first preset displacement;
[0094] (3) performing second laser etching in a preset area along a second direction, the second direction being opposite to the first direction; the second laser etching includes multiple second sub-etchings, the displacement of the laser along the second direction in each second sub-etching being a second preset displacement, and the distance between the starting points of two adjacent second sub-etchings being 100% of the second preset displacement.
[0095] Reference Figure 10 As shown, Figure 10 The direction of the first laser etching is from right to left. When the distance between the starting points of two adjacent first sub-etchings is 100% of the first preset displacement, black residue exists on the surface of the silicon wafer after the last first sub-etching.
[0096] Example 2
[0097] Laser etching:
[0098] (1) Providing a substrate, wherein a first silicon material layer is provided on a surface of the substrate, a protective layer is provided on a surface of the first silicon material layer away from the substrate, and the protective layer has a predetermined area on the surface away from the substrate;
[0099] (2) performing first laser etching in a preset area along a first direction, the first laser etching including multiple first sub-etchings, the displacement of the laser along the first direction in each first sub-etching being a first preset displacement, and the distance between the starting points of two adjacent first sub-etchings being 150% of the first preset displacement;
[0100] (3) performing second laser etching in a preset area along a second direction, the second direction being opposite to the first direction; the second laser etching includes multiple second sub-etchings, the displacement of the laser along the second direction in each second sub-etching being a second preset displacement, and the distance between the starting points of two adjacent second sub-etchings being 150% of the second preset displacement.
[0101] Reference Figure 11 As shown, Figure 11 The direction of the first laser etching is from right to left. When the distance between the starting points of two adjacent first sub-etchings is 150% of the first preset displacement, the black residue on the silicon wafer surface after the second first sub-etching is reduced compared to Example 1.
[0102] Example 3
[0103] Laser etching:
[0104] (1) Providing a substrate, wherein a first silicon material layer is provided on a surface of the substrate, a protective layer is provided on a surface of the first silicon material layer away from the substrate, and the protective layer has a predetermined area on the surface away from the substrate;
[0105] (2) performing first laser etching in a preset area along a first direction, the first laser etching including multiple first sub-etchings, the displacement of the laser along the first direction in each first sub-etching being a first preset displacement, and the distance between the starting points of two adjacent first sub-etchings being 190% of the first preset displacement;
[0106] (3) performing second laser etching in a preset area along a second direction, the second direction being opposite to the first direction; the second laser etching includes multiple second sub-etchings, the displacement of the laser along the second direction in each second sub-etching being a second preset displacement, and the distance between the starting points of two adjacent second sub-etchings being 190% of the second preset displacement.
[0107] Reference Figure 12 As shown, Figure 12 The direction of the first laser etching is from right to left. When the distance between the starting points of two adjacent first sub-etchings is 190% of the first preset displacement, the black residue on the silicon wafer surface after the latter first sub-etching is reduced compared to Examples 1 and 2.
[0108] Reference Figure 13 As shown, Figure 13 Figure 2 is an optical microscope image of the sample surface after the first and second laser etching in this embodiment. It can be seen that the laser etching uniformity of the sample obtained in this embodiment is good and the residue is small.
[0109] Comparative Example 1
[0110] Laser etching:
[0111] (1) Providing a substrate, wherein a first silicon material layer is provided on a surface of the substrate, a protective layer is provided on a surface of the first silicon material layer away from the substrate, and the protective layer has a predetermined area on the surface away from the substrate;
[0112] (2) Laser etching is performed in a preset area along a first direction, wherein the first laser etching includes multiple first sub-etchings, wherein the displacement of the laser along the first direction in each first sub-etching is a first preset displacement, and the distance between the starting points of two adjacent first sub-etchings is 100% of the first preset displacement.
[0113] Reference Figure 15 As shown, Figure 15 This is an optical microscope image of the sample surface after etching by the conventional laser etching method in this comparative example, wherein Figure 15 (a) is Figure 15 A partial enlarged schematic diagram of (b). It can be seen that there are many residues on the surface of the sample after etching, and the uniformity of laser etching is obviously poor.
[0114] The etched areas of the samples after laser etching in Example 3 and Comparative Example 1 were etched using an alkaline solution. The optical microscope images of the sample surfaces after etching with the alkaline solution were respectively referred to Figure 14 and Figure 16 As shown, it can be seen that after etching with alkaline solution, the sample in Example 3 has a better etching effect and less residue. After etching with alkaline solution, the sample in Comparative Example 1 has a poorer etching effect and more residue.
[0115] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0116] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make several modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the patent in this application shall be based on the appended claims, and the specification and drawings may be used to interpret the claims.
Claims
1. A laser etching method, characterized in that: The steps include: A substrate is provided, wherein a first silicon material layer is provided on a surface of the substrate, a protective layer is provided on a surface of the first silicon material layer away from the substrate, and the protective layer has a predetermined area on a surface away from the substrate; Performing first laser etching in the preset area along a first direction; Performing second laser etching in the preset area along a second direction, wherein the second direction is opposite to the first direction; An etched area is formed in the predetermined area.
2. The laser etching method according to claim 1, characterized in that: The material of the protective layer includes at least one of nitride and oxide; and / or, The material of the first silicon material layer is selected from at least one of doped or undoped amorphous silicon, doped or undoped single crystal silicon, and doped or undoped polycrystalline silicon.
3. The laser etching method according to claim 1, wherein: The first laser etching includes multiple first sub-etchings, the displacement of the laser along the first direction in each first sub-etching is a first preset displacement, and the distance between the starting points of two adjacent first sub-etchings is 20% to 200% of the first preset displacement; and / or, The second laser etching includes multiple second sub-etchings, the displacement of the laser along the second direction in each second sub-etching is a second preset displacement, and the distance between the starting points of two adjacent second sub-etchings is 20% to 200% of the second preset displacement.
4. The laser etching method according to claim 3, characterized in that: The distance between the starting points of two adjacent first sub-etchings is 20% to 100% of the first preset displacement, and the distance between the starting points of two adjacent second sub-etchings is 20% to 100% of the second preset displacement.
5. The laser etching method according to claim 4, characterized in that: The energy of the first laser etching is 0.1 J / cm 2 ~0.4J / cm 2 ; And / or, the energy of the second laser etching is 0.1 J / cm 2 ~0.4J / cm 2 .
6. The laser etching method according to claim 3, characterized in that: The distance between the starting points of two adjacent first sub-etchings is greater than the first preset displacement and less than or equal to 200% of the first preset distance, and the distance between the starting points of two adjacent second sub-etchings is greater than the second preset displacement and less than or equal to 200% of the second preset distance; The etched area of the second sub-etch covers the space between adjacent first sub-etches.
7. The laser etching method according to claim 6, characterized in that: The energy of the first laser etching is greater than 0.4 J / cm 2 and less than or equal to 0.8J / cm 2 ; And / or, the energy of the second laser etching is greater than 0.4 J / cm 2 and less than or equal to 0.8J / cm 2 .
8. A method for preparing a solar cell, characterized in that: The steps include: The protective layer is etched using the laser etching method according to any one of claims 1 to 7 to obtain an etched area.
9. The method for preparing a solar cell according to claim 8, wherein: After obtaining the etched area, the following steps are also included: performing wet etching on the etching area; A second silicon material layer is prepared in the etched area after wet etching, wherein the first silicon material layer includes a first doping element, and the second silicon material layer includes a second doping element. The doping types of the first doping element and the second doping element are opposite, and there is a gap between the second silicon material layer and the first silicon material layer.
10. A solar cell, characterized in that: The solar cell is prepared by the method for preparing the solar cell according to any one of claims 8 to 9.