Laser processing method and laser processing equipment for solar cell

Abstract

The invention provides a laser processing method and laser processing equipment for a solar cell, and the laser processing method comprises the steps: enabling a shaping and homogenizing light spot to move in the scanning direction to form a first processing region, and enabling an edge light spot to move in the scanning direction to form a second processing region, the two second machining areas are at least partially overlapped with the two sides of the first machining area in the scanning direction, the second machining areas cover the shaping and homogenizing light spot edge contour deformation area and / or the energy defect area, and the width size of the second machining areas is larger than the size, perpendicular to the scanning direction, of the edge contour deformation area and / or the energy defect area. Wherein the first processing area and the second processing area are formed at the same time or sequentially formed in any time sequence. The laser processing method effectively solves the technical problems that the processing effect in the whole processing breadth is inconsistent and the processing quality is affected due to the fact that the contour of the edge area of the shaping and homogenizing light spot is deformed and the tiny energy of the edge area is uneven.

Description

Technical Field

[0001] This application belongs to the field of laser processing technology, specifically relating to a laser processing method and laser processing equipment for solar cells. Background Technology

[0002] In the field of laser precision machining, the shaping and homogenizing of laser spots is widely used in laser micromachining processes such as scribing and grooving in the fabrication of solar cells due to its advantages such as uniform energy distribution, large spot area, and high processing efficiency.

[0003] Ideally, the shaped and homogenized light spot should have neat edges and uniform energy distribution across the entire field of view. However, in physical implementation, the actual output shaped and homogenized light spot generally suffers from uneven energy distribution, blurred transitions, and even localized deformation in the edge regions, such as... Figure 1 As shown. These problems are particularly pronounced in multi-spot scanning and splicing or continuous path processing, severely limiting processing accuracy and final device performance.

[0004] The causes of this problem are multifaceted. First, current mainstream beam shaping methods heavily rely on grating-based phase or amplitude modulation devices such as diffractive optical elements (DOEs) and spatial light modulators (SLMs), which are inherently limited by diffraction effects, finite resolution, and manufacturing errors. Second, laser sources are not ideal plane or spherical waves; their output beams often carry residual aberrations, causing wavefront distortion. When such non-ideal wavefronts are incident on phase modulation elements like DOEs, the actual phase modulation result is a superposition of "incident wavefront distortion" and "designed phase," resulting in unexpected interference and diffraction effects in the far field. This coupling effect is particularly pronounced in large-sized beams, potentially leading to abnormal energy enhancement or reduction in localized areas of the shaped and homogenized beam, or even overall contour shift or distortion. Third, the phase aberration of the focusing system: considering image quality balance and assembly, the focusing system is not perfectly aberration-free, leading to beam distortion.

[0005] Furthermore, when lasers are applied in photovoltaic processing, they are often used in conjunction with wet etching processes, such as for key steps like dielectric layer opening, selective etching of silicon substrates, or construction of specific surface structures. In these photovoltaic processing techniques, lasers are typically used for localized etching or modification to control the initiation position and depth of subsequent wet etching. However, silicon materials exhibit strong anisotropic etching in alkaline solutions, with etching rates for different crystal planes (such as {100} and {111}) differing by tens of times. If energy fluctuations occur at the edge of the shaping and homogenizing laser spot, even minor local overheating or underheating can cause the etching profile to deviate from the ideal shape due to the nonlinear amplification effect of anisotropic etching, or result in unexpected crystal plane exposure at the edge, affecting the photoelectric conversion efficiency of the photovoltaic cell.

[0006] To address the aforementioned issues, existing technologies primarily employ the following strategies: 1) optimizing the phase design algorithm of the DOE / SLM shaping device to suppress abnormal energy fluctuations in local edge regions; 2) using soft-edge flat-topped light spots, sacrificing edge steepness for energy smoothness. However, the algorithm optimization methods in these approaches are sensitive to system disturbances and exhibit poor robustness; soft edges expand the energy transition region, and these methods remain insufficient when facing anisotropic etching of silicon. In threshold etching, soft-edge flat-topped light spots can even induce wider non-uniform reaction bands.

[0007] In summary, there is an urgent need for a technical solution that can solve the problems of deformation and energy unevenness in the edge region of the laser spot without relying on extreme optical precision, so as to achieve high-quality and highly consistent laser processing results across the entire processing area. Summary of the Invention

[0008] In view of this, this application provides a laser processing method and laser processing equipment for solar cells.

[0009] According to one aspect of this application, a laser processing method for solar cells is proposed, comprising:

[0010] The light spot is shaped and homogenized and moved along the scanning direction to form the first processing area on the solar cell;

[0011] The edge spot moves along the scanning direction to form a second processing area on the solar cell. There are two second processing areas, which at least partially overlap with the first processing area on both sides of the scanning direction. The second processing area covers the edge contour deformation area and / or energy defect area of ​​the shaping and homogenizing spot. The width of the second processing area is greater than the dimension of the edge contour deformation area and / or energy defect area perpendicular to the scanning direction.

[0012] The first processing area and the second processing area are formed simultaneously or sequentially in any time order.

[0013] As a further example, the size range of the shaping and homogenizing spot is 40μm to 1000μm, and the size of the edge spot is 2μm to 50μm.

[0014] As a further example, the outer contour of the second processing area is a straight line, and the position fluctuation range of its outer contour in the direction perpendicular to the scanning direction is less than 2μm.

[0015] As a further example, the edge spot is a single-pulse laser or a pulse train laser.

[0016] As a further example, the edge spot is a pulse train laser, in which the connecting direction of multiple sub-pulses in each pulse train is not parallel to the scanning direction, and the projections of adjacent sub-pulses in each pulse train in the vertical scanning direction overlap.

[0017] As a further example, the edge spot is a single-pulse laser or a pulse train laser, and the edge spot includes any one of Gaussian spot, flat-top circular spot, flat-top square spot, annular spot, and linear spot;

[0018] When the edge spot is a Gaussian spot, the overlap rate of adjacent edge spots in the scanning direction is 50%~99%;

[0019] When the edge spot is a flat-topped circular spot, the overlap rate of adjacent edge spots in the scanning direction is 50%~99%;

[0020] When the edge spot is a flat-topped square spot, the overlap rate of adjacent edge spots in the scanning direction is 1% to 99%.

[0021] When the edge spot is a ring-shaped spot, the overlap rate of adjacent edge spots in the scanning direction is 50%~99%;

[0022] When the edge spot is a linear spot, the overlap rate of adjacent edge spots in the scanning direction is 1% to 99%.

[0023] As a further example, the width of the overlapping area between the first processing area and the second processing area is 30% to 100% of the width of the second processing area.

[0024] As a further example, the width of the second processing area is greater than H, where H = L × tanθ, and L is the center distance between two adjacent shaping and homogenizing spots, 0° < θ ≤ 10°.

[0025] As a further example, if the second processing area formed during a single scan of the edge spot cannot completely cover the edge contour deformation area and / or energy defect area, the edge spot is controlled to shift in a direction perpendicular to the scanning direction, and then scanned again until it can completely cover the area.

[0026] As a further example, the first processing area is formed by multiple scans of the shaping and homogenizing spot, and the areas of two adjacent scans at least partially overlap.

[0027] As a further example, the edge spot is a single point. First, the edge spot is moved along the scanning direction to form one of the second processing areas. Then, the edge spot is moved to the other side of the scanning direction and moved along the scanning direction to form another second processing area.

[0028] Alternatively, there may be two edge spots, which are simultaneously moved along the scanning direction to form two second processing areas.

[0029] As a further example, the edge spot is a single point, and the method for obtaining the edge spot and the shaping and homogenizing spot includes:

[0030] A first laser emits a first beam, which passes through a first shaping device to obtain a shaped and homogenized beam. After passing through a first laser scanning system, the beam is irradiated onto a solar cell to obtain the shaped and homogenized spot. The first laser scanning system includes a galvanometer and a field lens. The galvanometer controls the shaped and homogenized spot to move along the scanning direction on the solar cell.

[0031] A second laser is controlled to emit a second beam, which, after passing through a second laser scanning system, illuminates the solar cell to obtain the edge spot. The second laser scanning system includes a galvanometer and a field lens. The galvanometer controls the edge spot to move along the scanning direction to form one of the second processing areas. The galvanometer then controls the edge spot to move to the other side of the scanning direction and move along the scanning direction to form another second processing area.

[0032] As a further example, there are two edge light spots, and the first processing area and the two second processing areas are formed by successively using the shaping and homogenizing light spots and the two edge light spots;

[0033] Alternatively, there are two edge spots. The shaping and homogenizing spot is combined with the two edge spots to form a combined spot. The combined spot is controlled to move along the scanning direction, thereby forming the first processing area and two second processing areas.

[0034] As a further example, the first processing area and the two second processing areas are formed successively using the shaping and homogenizing light spot and the two edge light spots, respectively. The method for obtaining the edge light spot and the shaping and homogenizing light spot includes:

[0035] A first laser emits a first beam, which passes through a first shaping device to obtain a shaped and homogenized beam. After passing through a first laser scanning system, the beam is irradiated onto a solar cell to obtain the shaped and homogenized spot. The first laser scanning system includes a galvanometer and a field lens. The galvanometer controls the shaped and homogenized spot to move along the scanning direction on the solar cell.

[0036] The second laser emits a second beam, which is split into two separate beams by a beam splitter. After passing through the second laser scanning system, the beams are irradiated onto the solar cell to obtain two edge spots. The laser scanning system includes a galvanometer and a field mirror. The galvanometer controls the two edge spots to move simultaneously along the scanning direction to form two second processing areas.

[0037] As a further example, the shaping and homogenizing spot is combined with the two edge spots to form a combined spot, the distance between the two edge spots is d, the size of the shaping and homogenizing spot perpendicular to the scanning direction is L, the size of the edge spot is a, and d satisfies the formula (La) < d < (L + 0.4a).

[0038] As a further example, the shaping and homogenizing light spot is combined with the two edge light spots to form a combined light spot, and the method for obtaining the combined light spot includes:

[0039] The first laser is controlled to emit a first beam, which is then shaped and homogenized by the first shaping device.

[0040] The second laser is controlled to emit a second beam, which, after passing through a beam splitter, results in two separate beams.

[0041] The shaping and homogenizing beam and the two split beams are controlled to pass through a beam combiner and a third laser scanning system and then irradiate the solar cell to obtain a combined beam spot formed by combining the shaping and homogenizing beam spot and the two edge beam spots. The third laser scanning system includes a galvanometer and a field mirror. The galvanometer controls the movement of the combined beam spot along the scanning direction, thereby forming the first processing area and two second processing areas.

[0042] As a further example, the edge light spot is any one of a flat-top circular light spot, a flat-top square light spot, an annular light spot, or a linear light spot. The second beam is controlled to first be shaped by a second shaping device before finally illuminating the solar cell.

[0043] As a further example, the laser processing method further includes: controlling at least one of the first beam and the second beam to pass through a mirror, and adjusting the angle of the mirror so that the central axes of the two beams pass through the center of the shaping and homogenizing beam.

[0044] According to another aspect of this application, a laser processing apparatus is also proposed for processing solar cells using the laser processing method for solar cells described in any of the preceding claims.

[0045] The laser processing method for solar cells proposed in this application adopts a scheme that combines the shaping and homogenizing spot in the middle region with the edge spots on both sides. While maintaining a high degree of energy uniformity in the middle region, the edge spots on the sides form continuous energy to supplement the energy of the deformed area and / or energy defect area at the edge of the shaping and homogenizing spot. This effectively solves the technical problem of inconsistent processing results across the entire processing area and affecting processing quality caused by the deformation of the edge area of ​​the shaping and homogenizing spot and the slight energy unevenness in the edge area.

[0046] Furthermore, this laser processing method can avoid the drastic shift of anisotropic corrosion paths caused by minute energy differences at the edge of the shaping and homogenizing laser spot, effectively suppressing the amplified influence of edge energy anomalies on corrosion morphology. As a result, a good corrosion profile can be obtained, ultimately achieving a highly consistent and robust laser processing technology, thereby improving the photoelectric conversion efficiency of photovoltaic cells. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0048] The structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0049] Figure 1 This is a simulation diagram of a shaping and homogenizing light spot with edge contour deformation and edge energy defects in the prior art;

[0050] Figure 2 This is a schematic diagram of a shaping and homogenizing light spot with edge distortion in the prior art;

[0051] Figure 3 This is a schematic diagram of the laser spot used in a laser processing method proposed in this application;

[0052] Figure 4 This is an optical microscope image of a reshaping and homogenizing spot with edge distortion when using a galvanometer field microscope as a scanning system in the prior art;

[0053] Figure 5 An optical microscope image of the laser spot used in a laser processing method proposed in this application;

[0054] Figure 6 This is a schematic diagram of the structure of a laser processing device according to an embodiment of this application;

[0055] Figure 7 This is a schematic diagram of the structure of a laser processing device according to another embodiment of this application;

[0056] Figure 8 This is a diagram showing the edge morphology of the laser processing area in Comparative Example 1.

[0057] Figure 9 This is an edge topography diagram of the laser processing area in Example 2;

[0058] Figure 10 This is a diagram showing the outer contour of the second processing area in one embodiment.

[0059] Explanation of reference numerals in the attached figures: 001-First laser; 002-Second laser; 003-Reflector; 004-Beam expander; 005-First shaping device; 006-1 / 2 wave plate; 007-Beam combiner; 008-Galvanometer; 009-Field mirror; 010-Beam splitter; 011-Second shaping device. Detailed Implementation

[0060] The embodiments of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0061] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, this application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0062] To address the problem in existing laser processing where uneven energy distribution, blurred transitions, and even localized deformation are common at the edges of the shaping and homogenizing spot irradiated onto solar cells, leading to inconsistent processing results across the entire processing area and affecting processing quality, this application proposes a laser processing method for solar cells that utilizes edge spots to scan and compensate for deformed areas and / or edge energy defect areas at the edges of the shaping and homogenizing spot. Specifically, Figure 1 This is a simulation of a shaping and homogenizing light spot with edge contour deformation and edge energy defects. When the shaping and homogenizing light spot is actually applied to a solar cell, the edge energy defect region (edge ​​energy non-uniformity) is more obvious.

[0063] It should be noted that the laser processing in this application includes at least laser etching and laser modification. Laser etching involves removing the target material using a laser; laser modification involves modifying the target material using a laser to obtain a material surface with physical or chemical modification effects. For example, a laser-modified film may be more easily corroded by a specific etchant compared to an untreated film.

[0064] The laser processing method for solar cells proposed in this application includes:

[0065] A first processing area is formed on the solar cell by moving a shaping and homogenizing light spot along the scanning direction; a second processing area is formed on the solar cell by moving an edge light spot along the scanning direction. There are two second processing areas, which at least partially overlap with the first processing area on both sides of the scanning direction. The second processing area covers the edge contour deformation area and / or energy defect area of ​​the shaping and homogenizing light spot, and the width of the second processing area is greater than the size of the edge contour deformation area and / or energy defect area perpendicular to the scanning direction.

[0066] The first processing area and the second processing area are formed simultaneously or sequentially in any order.

[0067] Preferably, the size of the edge spot is smaller than the size of the shaping and homogenizing spot.

[0068] Specifically, the scanning direction is the direction in which the laser spot moves along the pattern to be processed. For example, when processing a single strip-shaped processing area, it moves along a straight line. Of course, the scanning direction can also be changed during laser processing depending on the pattern being processed. The laser processing in this application uses two types of laser spots: a shaping and homogenizing spot and an edge spot. The movement paths of the two are basically the same, except that their positions perpendicular to the scanning direction are offset during scanning, so that the edge spot can scan the edge deformation area of ​​the shaping and homogenizing spot.

[0069] In this application, when scanning with shaping and homogenizing spots and edge spots, the processing order of the two spots is not limited and can be flexibly set according to process requirements. Scanning can be performed simultaneously or sequentially. For example, in sequential scanning, energy distribution can be pre-compensated using the edge spot before processing the shaping and homogenizing spot, or vice versa, energy compensation can be performed using the edge spot after processing the shaping and homogenizing spot. Furthermore, since there are contour deformation areas and / or energy defect areas on both sides of the shaping and homogenizing spot's edge, edge spot scanning is required on both sides. There can be one edge spot, scanning both sides sequentially, or there can be two edge spots, scanning both sides simultaneously. Specific examples are provided below.

[0070] In this application, the dimensions of the shaping and homogenizing spot and the edge spot vary depending on their shape. For example, if the spot is circular, the dimension refers to its diameter; if it is a regular rectangle or square, the dimension refers to its side length. For instance, the outer contour of the shaping and homogenizing spot can be square, rectangular, or circular. The edge spot can be any one of a Gaussian spot, a flat-topped circular spot, a flat-topped square spot, annular spot, or linear spot. The dimension of a Gaussian spot or annular spot refers to its diameter, while the dimension of a flat-topped spot or linear spot refers to its side length. A flat-topped square spot includes both rectangles and squares.

[0071] The large size of the central shaping and homogenizing spot serves as the main processing unit, ensuring uniform laser energy distribution in most of the central processing area to achieve stable material removal depth or stable material modification effects. Meanwhile, the edge spots on both sides of the shaping and homogenizing spot can be used to solve the problem of edge deformation of the shaping and homogenizing spot, and their energy distribution covers the areas where the shaping and homogenizing spot may deform.

[0072] Furthermore, there are many ways to control the movement of the shaped and homogenized light spot and the edge light spot on the solar cell. For example, the light spot can be controlled to move along the scanning path using a laser scanning system. The laser scanning system includes a galvanometer and a field lens. The galvanometer is used to control the position of the light spot on the solar cell, and the field lens is used to focus the laser beam emitted by the laser onto the working plane. Alternatively, the movement of the support stage carrying the solar cell can be controlled. Or, the movement of the entire optical system can be controlled. The optical system must include at least the necessary optical components such as the laser and the field lens.

[0073] When using galvanometers and field mirrors as laser scanning systems, such as Figure 2 The diagram shown is a schematic of a shaping and homogenizing light spot with edge distortion in the prior art. In this case, in addition to having... Figure 1 The problem also includes spot distortion, where the edges of the spot become jagged. Furthermore, the width of the second processing area is greater than H, where H = L × tanθ, and L is the center distance between two adjacent shaping and homogenizing spots, 0° < θ ≤ 10°. This formula gives the condition when the edges of the shaping and homogenizing spot show jagged edges. Figure 2 The distortion shown illustrates the design basis and required conditions for the width dimension of the second processing area. L is... Figure 2 The distance between the protruding corner points of two adjacent shaping and homogenizing spots in the scanning direction is equivalent to the center distance between two adjacent shaping and homogenizing spots.

[0074] Figure 3 This is a schematic diagram of the laser spot used in a laser processing method proposed in this application, which can be used to... Figure 2 To improve this problem, in this example, the middle area is the first processing area, the edge spot is a Gaussian spot, and the area after the Gaussian spots on both sides overlap and scan is the second processing area. The first processing area overlaps with the second processing area.

[0075] Figure 4 This is an optical microscope image of a reshaping and homogenizing spot with edge distortion when using a galvanometer and field lens as a scanning system in the prior art. The image also shows that the edges of the scanned area are jagged. Figure 5 This is an optical microscope image of the laser spot used in a laser processing method proposed in this application. As can be seen from the image, due to the use of edge spot scanning on both sides, the area with contour deformation at the edge of the smooth and shaped spot is compensated.

[0076] The shaped and homogenized light spot of this application can be obtained by a shaping device, such as a diffractive optical element (DOE) commonly used in the prior art.

[0077] More specifically, the second processing area covers the edge contour deformation area and / or energy defect area, thereby replenishing the energy of the edge contour deformation area and / or energy defect area of ​​the shaping and homogenizing spot, solving the technical problem that the deformation and uneven energy in the edge area of ​​the shaping and homogenizing spot cause inconsistent processing effects throughout the entire processing area, affecting the processing quality.

[0078] The laser processing method for solar cells proposed in this application adopts a scheme that combines the shaping and homogenizing spot in the middle region with the edge spots on both sides. While maintaining a high degree of energy uniformity in the middle region, the edge spots on the sides form continuous energy to supplement the energy in the deformed area and / or energy defect area of ​​the edge contour of the shaping and homogenizing spot. This effectively solves the technical problem of inconsistent processing effect across the entire processing area due to deformation of the edge area of ​​the shaping and homogenizing spot and slight energy unevenness, which affects the processing quality.

[0079] Furthermore, when using galvanometers and field mirrors as scanning systems, this laser processing method can further compensate for the impact on processing results caused by jagged edges in such cases. Specifically, the edge spots on both sides achieve natural smoothing of irregular edges. In laser etching processes, it can effectively suppress jagged or wavy defects on the scribing or grooving sidewalls, achieving a high-quality processing morphology with a "flat bottom and straight edges," significantly reducing edge roughness. It can also reduce the accumulation of overheating in the substrate, shrink the heat-affected zone, and help maintain the crystal integrity of the silicon substrate. In laser modification processes, by controlling the overlap area and energy distribution of the edge spot and the shaping and homogenizing spot, controllable physical or chemical changes can be induced in the laser-processed area on the material surface. For example, it can induce a crystal phase transformation or chemical bond breaking in the processed area, thereby changing its dissolution rate in the subsequent chemical etching solution.

[0080] Furthermore, and importantly, when combined with wet etching, this laser processing method avoids the drastic shift in anisotropic etching paths caused by minute energy differences at the edges of the laser spot during shaping and homogenization. The laser-treated area exhibits significant etching selectivity compared to the untreated area. During wet etching, the etching proceeds directionally along the laser scanning path. This laser processing method effectively suppresses lateral diffusion and irregular etching, ultimately resulting in a flat lateral etching morphology, improving the geometric accuracy and consistency of the etched structure, and thus enhancing the photoelectric conversion efficiency of photovoltaic cells.

[0081] More specifically, when this laser processing method is applied to the processing of back-contact solar cells, the geometric regularity of the sidewalls directly affects the passivation quality of the cell. In processes requiring wet etching, the laser processing method of this application is used to complete the processing of the main path and edge areas. During subsequent etching, the etching proceeds along the laser scanning path, effectively suppressing lateral diffusion and thus forming a straight sidewall etching morphology. This high-quality sidewall structure facilitates the deposition of a uniform and dense passivation layer, significantly improving the passivation effect and the photoelectric performance of the device.

[0082] Furthermore, the size range of the shaping and homogenizing spot is 40μm~1000μm, for example, 40μm, 45μm, 50μm, 60μm, 80μm, 100μm, 120μm, 150μm, 200μm, 500μm, and 800μm; the size of the edge spot is 2μm~50μm, for example, 2μm, 5μm, 8μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, and 50μm. Regarding the size of the edge spot, if the size is too small, it may not completely cover the edge area requiring energy compensation; if the size is too large, it is not conducive to improving the smoothness of the processed edge, and may also cause excessive energy in the overlapping part of the first and second processing areas, leading to processing damage. Within this range, while achieving effective energy compensation, better processing results and a simpler control method can be guaranteed.

[0083] Furthermore, the width of the overlapping area between the first processing area and the second processing area is 30% to 100% of the width of the second processing area, preferably 50% to 100%, thereby ensuring coverage of the edge area requiring energy compensation. The width of the second processing area is the width of a single-sided second processing area perpendicular to the scanning direction.

[0084] Furthermore, the outer contour line of the second processing area is a straight line, and the positional fluctuation range of the outer contour line of the second processing area perpendicular to the scanning direction is less than 2μm. Considering that the curvature of the outer contour line of the second processing area is extremely small, it can be regarded as a straight line. The positional fluctuation range of the outer contour line refers to the distance between the two outer envelope parallel lines, defined by the positions of the two largest fluctuation points on both sides of the outer contour line. (See [reference needed]). Figure 10 It should also be noted that in solar cells, due to the thickness of the processed area, the positional fluctuation range of the outer contour line of the second processed area on each horizontal plane in the thickness direction is less than 2 μm. Specifically, when measuring the positional fluctuation range of the outer contour line, for example, an electron microscope can be used, or other methods can also be used. If it is not possible to measure the entire length of the outer contour line globally, multiple measurements can be taken at different positions along the length, and the average value can be taken.

[0085] Furthermore, the edge spot is a single-pulse laser or a pulse train laser, specifically, for example, a nanosecond or picosecond pulse laser.

[0086] Furthermore, the edge spot is a pulse train laser, and the line connecting multiple sub-pulses (spots) in each pulse train is not parallel to the scanning direction. Moreover, the projections of adjacent sub-pulses in each pulse train in the vertical scanning direction overlap. Using the edge spot in the form of a pulse train laser can reduce the laser thermal effect.

[0087] Furthermore, the edge spot is a single-pulse laser or a pulse train laser, and the edge spot includes any one of the following: Gaussian spot, flat-topped circular spot, flat-topped square spot, annular spot, and linear spot. When the edge spot is a Gaussian spot, the overlap rate of adjacent edge spots in the scanning direction is 50%~99%; when the edge spot is a flat-topped circular spot, the overlap rate of adjacent edge spots in the scanning direction is 50%~99%; when the edge spot is a flat-topped square spot, the overlap rate of adjacent edge spots in the scanning direction is 1%~99%; when the edge spot is an annular spot, the overlap rate of adjacent edge spots in the scanning direction is 50%~99%; when the edge spot is a linear spot, the overlap rate of adjacent edge spots in the scanning direction is 1%~99%, achieving good compensation effect and processing uniformity. Within this range, the outer contour line of the second processing area after wet etching forms a straight side corrosion morphology, and the fluctuation range of the outer contour line perpendicular to the scanning direction can be less than 10μm. The definition and measurement method of the fluctuation range of the outer contour line after corrosion can be found in the content described above.

[0088] Furthermore, if the second processing area formed during a single scan of one side of the processing area by the edge spot cannot completely cover the edge deformation area, that is, if the size of the edge spot is small and the overlapping area of ​​a single scan is insufficient, the edge spot can be shifted a certain distance in a direction perpendicular to the scanning direction and then scanned again until it can completely cover the area. In this way, even when the size of the shaping and homogenizing spot is relatively large or the size of the edge spot used is relatively small, the edge spot can still be used to compensate for energy in the edge region.

[0089] Furthermore, the first processing area can be formed either by a single scan of the shaping and homogenizing spot or by multiple scans of the shaping and homogenizing spot. When the first processing area is formed by multiple scans of the shaping and homogenizing spot, the adjacent scan areas should at least partially overlap to ensure uniform energy in the middle region of the first processing area. The scan areas formed by multiple scans are arranged along a direction perpendicular to the scanning direction. Regardless of whether the first processing area is formed by a single scan or multiple scans of the shaping and homogenizing spot, as long as the two second processing areas are located on both sides of the scanning direction of the first processing area and at least partially overlap with the first processing area, energy compensation can be performed on the deformed area and / or energy defect area of ​​the edge contour of the shaping and homogenizing spot through the edge spot.

[0090] Furthermore, as mentioned above, when using shaping and homogenizing light spots and edge light spots for scanning, the order of processing time for the two types of light spots is not limited. They can be scanned simultaneously or sequentially. At the same time, considering that there are edge deformation areas on both sides of the shaping and homogenizing light spot, there are multiple scanning methods.

[0091] Specifically, as one example, there is one edge spot. First, the edge spot moves along the scanning direction to form one of the second processing areas. Then, the edge spot is moved to the other side of the shaping and homogenizing spot and moves along the scanning direction to form another second processing area. There are three possible methods: First, the shaping and homogenizing spot scans and completes the first processing area, and the edge spot scans and completes the two second processing areas in sequence; Second, the edge spot scans and completes the two second processing areas in sequence, and then the shaping and homogenizing spot scans and completes the first processing area; Third, the edge spot scans and completes one of the second processing areas, then the shaping and homogenizing spot scans and completes the first processing area, and finally the edge spot scans and completes the second second processing area.

[0092] As another example, there are two edge spots. Both edge spots move simultaneously along the scanning direction to form two second processing areas. In this case, either the shaping and homogenizing spot and the two edge spots can be used sequentially to form the first processing area and the two second processing areas respectively; or the shaping and homogenizing spot and the two edge spots can be combined to form a combined spot. This combined spot is then controlled to move along the scanning direction, simultaneously forming the first processing area and the two second processing areas. In this case, the size of the combined spot perpendicular to the scanning direction is the size of the processing area formed by the first processing area and the two second processing areas perpendicular to the scanning direction. That is, when there are two edge spots, there are also three methods: First, the shaping and homogenizing spot scans to complete the first processing area, and then the two edge spots simultaneously scan to complete the two second processing areas; second, the two edge spots simultaneously scan to complete the two second processing areas, and then the shaping and homogenizing spot scans to complete the first processing area; third, the combined spot moves along the scanning direction, simultaneously forming the first processing area and the two second processing areas.

[0093] For embodiments with two edge spots, the two edge spots can be obtained by splitting a single laser beam using a beam splitter. The beam splitter can be a conventional optical device in the prior art, and any beam splitter that can achieve this function is within the scope of protection of this application. Furthermore, when using two edge spots simultaneously, it is possible that the second processing area formed by the two edge spots in a single scan may not completely cover the edge contour deformation area and / or the edge energy defect area. Preferably, the two edge spots can be simultaneously offset along a direction perpendicular to the scanning direction and scanned again until complete coverage is achieved.

[0094] When there is only one edge spot, the following can be used: Figure 6The laser processing equipment shown performs laser processing. This equipment includes at least a first laser 001, a second laser 002, a first shaping device 005, a galvanometer 008, and a field lens 009. The methods for obtaining the edge spot and the shaping / homogenizing spot include:

[0095] The first laser 001 is controlled to emit a first beam, which passes through the first shaping device 005 to obtain a shaped and homogenized beam, and then passes through the first laser scanning system to irradiate the solar cell to obtain a shaped and homogenized light spot; the first laser scanning system includes a galvanometer 008 and a field lens 009, and the shaped and homogenized light spot is controlled to move along the scanning direction on the solar cell through the galvanometer 008.

[0096] The second laser 002 is controlled to emit a second beam, which is then irradiated onto the solar cell after passing through the second laser scanning system to obtain an edge spot. The second laser scanning system includes a galvanometer 008 and a field lens 009. The galvanometer 008 controls the edge spot to move along the scanning direction to form one of the second processing areas. The galvanometer 008 then controls the edge spot to move to the other side of the scanning direction and move along the scanning direction to form another second processing area.

[0097] Figure 6 The example shown illustrates laser processing completed at two workstations, where the same solar cell is being processed at both stations. Processing can also be performed at a single workstation, provided the required spot size and desired effect are met.

[0098] Furthermore, when the edge light spot adopts any one of the following: a flat-top circular light spot, a flat-top square light spot, a ring light spot, or a linear light spot, the second beam is controlled to first pass through the second shaping device 011 to obtain the desired edge light spot, and finally illuminate the solar cell. Whether or not the second shaping device 011 needs to be added depends on the type of light spot used.

[0099] As another embodiment, when there are two edge spots, and the first processing area and two second processing areas are formed successively by shaping and homogenizing the two edge spots, the method for obtaining the edge spots and the shaping and homogenizing spots includes:

[0100] A first laser is controlled to emit a first beam, which passes through a first shaping device to obtain a shaped and homogenized beam. After passing through a first laser scanning system, the beam is irradiated onto a solar cell to obtain a shaped and homogenized spot. The first laser scanning system includes a galvanometer and a field lens. The galvanometer controls the shaped and homogenized spot to move along the scanning direction on the solar cell. A second laser is controlled to emit a second beam, which passes through a beam splitter to obtain two separate beams. After passing through a second laser scanning system, the beam is irradiated onto the solar cell to obtain two edge spots. The laser scanning system includes a galvanometer and a field lens. The galvanometer controls the two edge spots to move simultaneously along the scanning direction to form two second processing areas.

[0101] The laser processing equipment used in this embodiment only needs to be in Figure 6 Simply add a beam splitter to the laser processing equipment shown.

[0102] As another embodiment, in the embodiment where the shaping and homogenizing spot is combined with two edge spots to form a combined spot, the combined spot is preferably obtained by using two lasers to emit laser beams separately and then combining them through a beam combiner. The specific process for obtaining this combined spot can be found in the description below. This processing method, because it uses the method of combining the central shaping and homogenizing spot with the two edge spots, means that the two spots simultaneously complete the processing of the main body and edges. This not only greatly improves production capacity, but also ensures that the relative positions of the shaping and homogenizing spot and the two edge spots are fixed before light emission, which helps to ensure the relative positional accuracy of the shaping and homogenizing spot and the edge spots, improving processing consistency and repeatability.

[0103] Furthermore, in the embodiment where the shaping and homogenizing spot is combined with two edge spots to form a combined spot, when controlling the combined spot to move along the scanning path, the scanning direction of the combined spot is not parallel to the direction of the line connecting the centers of the two edge spots. Preferably, the angle between the scanning direction and the direction of the line connecting the centers of the two edge spots is 30°~90°. More preferably, the angle between the scanning direction and the direction of the line connecting the centers of the two edge spots is 80°~90°, the closer to 90° the better, and more preferably, the scanning direction is perpendicular to the direction of the line connecting the centers of the two edge spots. When the angle between the scanning direction and the direction of the line connecting the centers of the two edge spots is greater than or equal to 30° and less than 90°, at the beginning and end stages of laser processing, at least one side of the shaping and homogenizing spot may not be able to fully overlap with the edge spots simultaneously. In actual processing, this part can be excluded, and the remaining area is considered as the actual effective processing area of ​​the laser processing. Within this range, the closer the angle is to 90°, the smaller the ineffective processing area and the smaller the impact of the spacing fluctuation between the two edge spots. Preferably, the line connecting the centers of the two edge spots in the beam combining spot is perpendicular to the scanning direction of the beam combining spot. This setting makes control easier and operation simpler. The centers of the two edge spots are equidistant from the center of the shaping and homogenizing spot to achieve better processing results.

[0104] As a further supplement to the beam combining embodiment, the distance between the two edge spots is d, the dimension of the shaping and homogenizing spot perpendicular to the scanning direction is L, and the dimension of the edge spot is a. d satisfies the formula (La) < d < (L + 0.4a). Within this range, the width of the overlapping area between the first processing area and the second processing area can be 30% to 100% of the width of the second processing area, achieving good edge processing results and ensuring uniformity on both sides of the edge. The dimension of the edge spot can be referred to the description above, with the side length being the side length perpendicular to the scanning direction.

[0105] Furthermore, in the embodiment of beam combining, considering that the size of the edge spot is smaller than that of the shaping and homogenizing spot, in order to ensure that the entire shaping and homogenizing spot overlaps with the edge spot during laser processing, the edge spot needs to be emitted at a higher frequency. Preferably, the emission frequency of the edge spot is controlled to be more than 6 times that of the shaping and homogenizing spot, so that the overlap rate of adjacent edge spots in the scanning direction is ≥50%, forming a continuous and uninterrupted energy envelope to ensure the laser processing effect. Within this range, the higher the emission frequency of the edge spot, the smoother the final processed edge. For this embodiment, for ease of control, preferably, the number and overlap rate of the edge spots overlapping with the shaping and homogenizing spot are the same. In addition, it should be noted that since the emission frequencies of the middle shaping and homogenizing spot and the edge spots on both sides are different, when the first and last shaping and homogenizing spots at the beginning and end do not have enough edge spots to overlap with, the part excluding the beginning and end is the actual effective processing area. During laser processing, only the spot in the effective processing area illuminates the solar cell.

[0106] A further supplement to the embodiment of beam combining is to obtain the beam combining spot using two lasers, which can be achieved by employing... Figure 7 The laser processing equipment shown performs laser processing. This laser processing equipment includes at least a first laser 001, a second laser 002, a first shaping device 005, a galvanometer 008, a field lens 009, a beam splitter 010, and a beam combiner 007. The method for obtaining the combined beam spot includes:

[0107] The first laser 001 is controlled to emit a first beam, which is then shaped and homogenized by the first shaping device 005.

[0108] The second laser 002 is controlled to emit a second beam, which, after passing through the beam splitter 010, results in two separate beams.

[0109] After the shaping and homogenizing beam and the two split beams pass through the beam combiner 007 and the third laser scanning system, they are irradiated onto the solar cell to obtain a combined beam spot formed by combining the shaping and homogenizing beam spot and the two edge beam spots. The third laser scanning system includes a galvanometer 008 and a field mirror 009. The galvanometer 008 controls the combined beam spot to move along the scanning direction, while simultaneously forming a first processing area and two second processing areas.

[0110] Furthermore, in the above embodiment of obtaining a combined beam spot using a first laser and a second laser, the laser wavelengths output by the first laser and the second laser are the same. This ensures the beam combining effect and avoids the problem of inconsistent relative positions of the edge and top beam spots, which necessitates eliminating chromatic aberration when the wavelengths are inconsistent. Even further, the first laser and the second laser are pulsed lasers, and the pulse widths of the pulsed lasers output by the first laser and the second laser are the same, thereby ensuring better consistency in processing results.

[0111] Furthermore, in the above embodiment of obtaining a combined beam spot using the first laser and the second laser, the laser processing method further includes: controlling the first beam to pass through the beam expander 004 before passing through the first shaping device 005 to adjust the size of the shaped and homogenized beam spot; and / or controlling the second beam to pass through the beam expander 004 to adjust the size of the second beam, thereby making the shaped and homogenized beam spot and the edge beam spot sizes meet the processing requirements.

[0112] Furthermore, in order to effectively align the two edge beams with the deformed area of ​​the shaping and homogenizing beam, in the embodiment described above that uses the first laser 001 and the second laser 002 to obtain a combined beam, in addition to controlling the beam size and beam splitting distance, the centers of the two beams are aligned in advance. Specifically, the laser processing method also includes: controlling at least one of the first beam and the second beam to pass through the reflector 003, and adjusting the angle of the reflector 003 so that the central axes of the two beam splitting beams pass through the center of the shaping and homogenizing beam, thereby precisely controlling the relative position of the edge beams with respect to the shaping and homogenizing beam, and improving processing accuracy. Of course, this reflector 003 can also be used to change the beam direction at the same time.

[0113] Furthermore, the beam combiner 007 is a polarization beam combiner. The laser processing equipment also includes a half-wave plate 006 located between the first shaping device 005 and the beam combiner 007, and a half-wave plate 006 located between the beam splitter 010 and the beam combiner 007. The shaped and homogenized beam and the split beam are combined by the polarization beam combiner after passing through the half-wave plate 006. The first laser 001 and the second laser 002 are modulated by their respective half-wave plates 006, making the first beam a P-beam and the second beam an S-beam. After passing through the polarization beam combiner, the P-beam is combined by reflecting the S-beam.

[0114] The first shaping device 005, the second shaping device 011, and the beam splitter 010 in the above embodiments can all be conventional devices in the prior art, and optical devices that can achieve the corresponding functions are all within the protection scope of this application. Preferably, the beam combiner 007 is a polarization beam combiner.

[0115] The following section will illustrate this laser processing method in the application of a specific solar cell.

[0116] Example 1

[0117] In the fabrication process of back-contact solar cells, during laser processing, the shaping and homogenizing spot and the edge spot are controlled to move along the scanning direction on the functional layer of the semi-finished back-contact solar cell, completing the processing of multiple spaced strip-shaped regions. The continuous energy formed by the edge spots on both sides is used to perform energy compensation and natural smoothing of the deformed areas and / or energy defect areas of the shaping and homogenizing spot contour, improving the quality of the processed edges. Specifically:

[0118] A laser processing method for solar cells, used to prepare the p-region, n-region, and GAP region of a back-contact solar cell, includes the following steps:

[0119] S10, n-type silicon wafers are polished on both sides;

[0120] S20. A tunneling oxide layer and a boron-doped polysilicon layer are prepared on the back side of the silicon wafer, and a first mask layer is formed on the boron-doped polysilicon.

[0121] S30. Perform the first laser patterning process on the back of the silicon wafer, that is, form multiple spaced first strip regions. Specifically, control the shaping and homogenizing spot and the edge spot to scan along the first direction to form multiple spaced strip regions in the second direction.

[0122] S40. Wet cleaning removes the boron-doped polysilicon layer and tunnel oxide layer corresponding to the area of ​​the first laser patterning process.

[0123] S50. A tunneling oxide layer and a phosphorus-doped polysilicon layer are prepared on the back side of the silicon wafer, and a second mask layer is formed on the phosphorus-doped polysilicon.

[0124] S60. Perform a second laser patterning process on the back of the silicon wafer to form multiple spaced second strip-shaped regions. Specifically, control the shaping and homogenizing spot and the edge spot to scan along the first direction to form multiple strip-shaped regions spaced in the second direction.

[0125] S70. Wet cleaning removes the phosphorus-doped polysilicon layer and tunneling oxide layer corresponding to the second laser patterning processing area, and forms a GAP region of a certain depth between adjacent P and N regions.

[0126] S80, pickling, texturing, pickling. Specifically, pickling removes the phosphorus-doped and boron-doped polysilicon layers plated around the front edge. The N-region on the back is protected by a second mask layer, and the P-region is protected by a first mask layer, preventing further corrosion. Then, double-sided texturing is performed using an alkaline solution, forming a textured surface on the front and back GAP areas of the silicon wafer. Finally, hydrofluoric acid pickling removes the remaining first and second mask layers on the back.

[0127] S90. Prepare a front passivation layer and a back passivation layer on a silicon wafer;

[0128] S100, metallization of the back side of the silicon wafer, completes the fabrication of the back contact solar cell.

[0129] The above method employs coordinated processing of the shaping and homogenizing laser spot and the edge spot to achieve stable processing and simultaneously form a relatively smooth laser GAP area side surface. In this embodiment, the order of processing the shaping and homogenizing laser spot and the edge spot is not limited.

[0130] Example 2

[0131] This method is applied to the surface of monocrystalline silicon solar cells that already have a pyramidal textured surface, aiming to remove the pyramidal textured surface in specific areas to form a de-textured zone. This embodiment uses a beam-combining laser for processing. During laser processing, the beam-combining spot is controlled to move across the surface of the semi-finished cell to complete the laser processing of specific areas on the surface. Preferably, the width of the processing line is the width of the processing area. Specifically:

[0132] A laser processing method for solar cells, used to prepare de-texturing areas on a silicon wafer with a pyramidal textured surface, includes the following steps:

[0133] 1. Provide a silicon substrate with a pyramid-shaped textured surface, the textured surface of which is also covered with a mask layer;

[0134] 2. A laser processing is performed on a mask layer in a specific area on the surface of a silicon substrate to form a laser-modified region; specifically, the beam-combining spot is controlled to scan the region along a preset trajectory, and preferably the width of the modified region is close to the size of the beam-combining spot perpendicular to the scanning direction; wherein, the beam-combining spot is obtained by combining the shaping and homogenizing spot with two edge spots;

[0135] 3. Perform wet chemical etching on the laser-modified area to selectively remove the pyramid-shaped texturing structure in the area, forming a detexturing zone at this location;

[0136] 4. Subsequent processes include passivation and electrode fabrication.

[0137] By employing the combined processing of shaping and homogenizing laser spots and edge laser spots, the area is easily removed by subsequent wet etching, achieving a highly stable de-textured area with relatively neat laser edges.

[0138] Comparative Example 1

[0139] The battery de-furting region was prepared using the same method as in Example 2, except that the beam combining spot of the present application was not used, but a single shaping and homogenizing spot with the same size as the beam combining spot in the direction perpendicular to the scanning direction was used for processing.

[0140] Figure 8 and Figure 9 Comparative images of the edge morphology after laser processing and wet etching in Comparative Example 1 and Example 2 are shown respectively. Among them, from... Figure 8It can be seen that the de-linting area prepared in Comparative Example 1 exhibits serrated defects at the processing edge, resulting in an uneven edge. Furthermore, due to the use of a single shaping and homogenizing spot, significant thermal damage occurs at the edge, leading to corrosion pits at the pyramid apex in the non-laser region. Meanwhile, from... Figure 9 As can be seen, in Embodiment 2 of this application, by using a combined beam pattern of a central shaping and homogenizing spot and two edge spots, the wet etching process produces a high-quality morphology. The edges no longer have serrated defects, are smooth, and have significantly reduced roughness. Furthermore, the pyramid morphology in the non-laser area is more complete than in Embodiment 2.

[0141] According to another aspect of this application, a laser processing device is also proposed for processing solar cells using the laser processing method for solar cells described in any of the above embodiments. This laser processing device effectively solves the technical problem of inconsistent processing results across the entire processing area, which is caused by deformation in the edge region of the shaping and homogenizing laser spot and minute energy inhomogeneities, thus affecting processing quality.

[0142] The various embodiments in this specification are described in a progressive, parallel, or combined manner. Each embodiment focuses on its differences from other embodiments, and similar or identical parts between embodiments can be referred to interchangeably. For the apparatuses disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0143] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A laser processing method for solar cells, characterized in that, include: The light spot is shaped and homogenized and moved along the scanning direction to form the first processing area on the solar cell; An edge light spot is moved along the scanning direction to form a second processing area on the solar cell. There are two second processing areas, which at least partially overlap with the first processing area on both sides of the scanning direction. The second processing area covers the edge contour deformation region and / or energy defect region of the shaping and homogenizing spot, and the width of the second processing area is greater than the dimension of the edge contour deformation region and / or energy defect region perpendicular to the scanning direction; The first processing area and the second processing area are formed simultaneously or sequentially in any order.

2. The laser processing method for solar cells according to claim 1, characterized in that, The size range of the shaping and homogenizing light spot is 40μm~1000μm, and the size of the edge light spot is 2μm~50μm.

3. The laser processing method for solar cells according to claim 1, characterized in that, The outer contour of the second processing area is a straight line, and the position fluctuation range of its outer contour in the direction perpendicular to the scanning direction is less than 2μm.

4. The laser processing method for solar cells according to claim 1, characterized in that, The edge spot is a single-pulse laser or a pulse train laser.

5. The laser processing method for solar cells according to claim 1, characterized in that, The edge spot is a pulse train laser. The line connecting multiple sub-pulses in each pulse train is not parallel to the scanning direction, and the projections of adjacent sub-pulses in each pulse train overlap in the vertical scanning direction.

6. The laser processing method for solar cells according to any one of claims 1 to 5, characterized in that, The edge spot is a single-pulse laser or a pulse train laser, and the edge spot includes any one of Gaussian spot, flat-top circular spot, flat-top square spot, ring spot, and linear spot. When the edge spot is a Gaussian spot, the overlap rate of adjacent edge spots in the scanning direction is 50%~99%; When the edge spot is a flat-topped circular spot, the overlap rate of adjacent edge spots in the scanning direction is 50%~99%; When the edge spot is a flat-topped square spot, the overlap rate of adjacent edge spots in the scanning direction is 1% to 99%. When the edge spot is a ring-shaped spot, the overlap rate of adjacent edge spots in the scanning direction is 50%~99%; When the edge spot is a linear spot, the overlap rate of adjacent edge spots in the scanning direction is 1% to 99%.

7. The laser processing method for solar cells according to claim 1, characterized in that, The width of the overlapping area between the first processing area and the second processing area is 30% to 100% of the width of the second processing area.

8. The laser processing method for solar cells according to claim 1, characterized in that, The width of the second processing area is greater than H, where H = L × tanθ, and L is the center distance between two adjacent shaping and homogenizing spots, 0° < θ ≤ 10°.

9. The laser processing method for solar cells according to claim 1, characterized in that, If the second processing area formed during a single scan of the edge spot cannot completely cover the edge contour deformation area and / or energy defect area, the edge spot is controlled to shift in a direction perpendicular to the scanning direction, and then scanned again until it can completely cover the area.

10. The laser processing method for solar cells according to claim 1, characterized in that, The first processing area is formed by multiple scans of the shaping and homogenizing light spot, and the areas of two adjacent scans at least partially overlap.

11. The laser processing method for solar cells according to claim 1, characterized in that, The edge spot is one. First, the edge spot is moved along the scanning direction to form one of the second processing areas. Then, the edge spot is moved to the other side of the scanning direction and moved along the scanning direction to form another second processing area. Alternatively, there may be two edge spots, which are simultaneously moved along the scanning direction to form two second processing areas.

12. The laser processing method for solar cells according to claim 11, characterized in that, The edge light spot is one, and the method for obtaining the edge light spot and the shaping and homogenizing light spot includes: A first laser emits a first beam, which passes through a first shaping device to obtain a shaped and homogenized beam. After passing through a first laser scanning system, the beam is irradiated onto a solar cell to obtain the shaped and homogenized spot. The first laser scanning system includes a galvanometer and a field lens. The galvanometer controls the shaped and homogenized spot to move along the scanning direction on the solar cell. A second laser is controlled to emit a second beam, which, after passing through a second laser scanning system, illuminates the solar cell to obtain the edge spot. The second laser scanning system includes a galvanometer and a field lens. The galvanometer controls the edge spot to move along the scanning direction to form one of the second processing areas. The galvanometer then controls the edge spot to move to the other side of the scanning direction and move along the scanning direction to form another second processing area.

13. The laser processing method for solar cells according to claim 11, characterized in that, The edge light spot is two, and the first processing area and the two second processing areas are formed by successively using the shaping and homogenizing light spot and the two edge light spots; Alternatively, there are two edge spots. The shaping and homogenizing spot is combined with the two edge spots to form a combined spot. The combined spot is controlled to move along the scanning direction, thereby forming the first processing area and two second processing areas.

14. The laser processing method for solar cells according to claim 13, characterized in that, The first processing area and two second processing areas are formed sequentially using the shaping and homogenizing light spot and two edge light spots, respectively. The method for obtaining the edge light spot and the shaping and homogenizing light spot includes: A first laser emits a first beam, which passes through a first shaping device to obtain a shaped and homogenized beam. After passing through a first laser scanning system, the beam is irradiated onto a solar cell to obtain the shaped and homogenized spot. The first laser scanning system includes a galvanometer and a field lens. The galvanometer controls the shaped and homogenized spot to move along the scanning direction on the solar cell. The second laser emits a second beam, which is split into two separate beams by a beam splitter. After passing through the second laser scanning system, the beams are irradiated onto the solar cell to obtain two edge spots. The laser scanning system includes a galvanometer and a field mirror. The galvanometer controls the two edge spots to move simultaneously along the scanning direction to form two second processing areas.

15. The laser processing method for solar cells according to claim 13, characterized in that, The shaping and homogenizing spot and the two edge spots are combined to form a combined spot. The distance between the two edge spots is d. The size of the shaping and homogenizing spot perpendicular to the scanning direction is L. The size of the edge spot is a. d satisfies the formula (La) < d < (L + 0.4a).

16. The laser processing method for solar cells according to claim 13, characterized in that, The shaping and homogenizing light spot is combined with the two edge light spots to form a combined light spot, and the method for obtaining the combined light spot includes: The first laser is controlled to emit a first beam, which is then shaped and homogenized by the first shaping device. The second laser is controlled to emit a second beam, which, after passing through a beam splitter, results in two separate beams. The shaping and homogenizing beam and the two split beams are controlled to pass through a beam combiner and a third laser scanning system and then irradiate the solar cell to obtain a combined beam spot formed by combining the shaping and homogenizing beam spot and the two edge beam spots. The third laser scanning system includes a galvanometer and a field mirror. The galvanometer controls the movement of the combined beam spot along the scanning direction, thereby forming the first processing area and two second processing areas.

17. The laser processing method for solar cells according to any one of claims 12, 14, and 16, characterized in that, The edge light spot is any one of a flat-top circular light spot, a flat-top square light spot, an annular light spot, or a linear light spot. The second beam is controlled to first be shaped by the second shaping device before finally illuminating the solar cell.

18. The laser processing method for solar cells according to claim 16, characterized in that, The laser processing method further includes: controlling at least one of the first beam and the second beam to pass through a reflector, and adjusting the angle of the reflector so that the central axes of the two beams pass through the center of the shaping and homogenizing beam.

19. A laser processing device, characterized in that, The solar cell is processed using the laser processing method for solar cells according to any one of claims 1 to 18.

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