Method and apparatus for processing solar cells with multiple laser spots

Abstract

The application provides a multi-laser spot processing method and device for a solar cell. The multi-laser spot processing method for the solar cell comprises the following steps: a plurality of laser spots arranged in a straight line are formed on a substrate to be processed by splitting and focusing a laser beam emitted by a laser generating system, the energy of the plurality of laser spots is all the same, partially the same or all different; and the laser spots are scanned and processed according to a set speed and a scanning direction, wherein the scanning direction is consistent with the arrangement direction of the plurality of laser spots, so that the plurality of laser spots reach a same processing position in sequence. The application solves the problems of poor efficiency and poor process adaptability of the multi-laser spot processing method for the solar cell in the prior art.

Description

Technical Field

[0001] This invention relates to the field of laser precision processing equipment technology, and more specifically, to a method and apparatus for processing solar cells using multiple laser spots. Background Technology

[0002] With the development of technology, the solar cell industry has reached a high level of maturity. Cost reduction and efficiency improvement have always been the goals pursued by the solar cell industry. As photovoltaic technology continues to develop, technologies such as back passivation of solar cells, selective doping, and half-cell module technology are gradually becoming standard features on production lines.

[0003] Lasers are an indispensable tool in current solar cell technologies such as back passivation, selective emitter, and half-cell, and are widely used in production lines.

[0004] Currently, the laser processing method for solar cells in the solar cell industry generally adopts a single laser beam and single scanning head reciprocating scanning processing method. Its disadvantage is that a single laser beam with a fixed laser energy can only process a specific position. If the laser energy needs to be changed according to the process requirements, repeated engraving and scanning are required, which increases the laser repeated scanning processing time and the complexity of graphic settings. Moreover, the processing effect is difficult to guarantee, which limits the secondary development of solar cell laser technology and is not conducive to the in-depth development of laser technology applications.

[0005] In other words, existing multi-laser spot processing methods for solar cells suffer from poor efficiency and poor process adaptability. Summary of the Invention

[0006] The main objective of this invention is to provide a multi-laser spot processing method and apparatus for solar cells, so as to solve the problems of poor efficiency and poor process adaptability in the existing multi-laser spot processing methods for solar cells.

[0007] To achieve the above objectives, according to one aspect of the present invention, a method for processing multiple laser spots on a solar cell is provided, comprising: a laser beam emitted by a laser generating system is split and focused to form multiple laser spots arranged in a straight line on a substrate to be processed, wherein the energy of the multiple laser spots is all the same, partially the same, or all different; the laser spots are scanned and processed according to a set speed and scanning direction, wherein the scanning direction is consistent with the arrangement direction of the multiple laser spots, so that the multiple laser spots arrive at the same processing position in sequence.

[0008] Furthermore, the multiple laser spots may be the same size or different sizes.

[0009] Furthermore, the laser beam emitted by the laser generating system, after being split and focused, yields multiple laser spots: the shape of the multiple laser spots includes one of the following: circular, rectangular, and square; the size of the multiple laser spots is in the range of 6μm to 500μm; the distance between two adjacent laser spots is in the range of 0μm to 10μm; and the number of multiple laser spots is 2 to 6.

[0010] Furthermore, when the energies of multiple laser spots are all different, the energies of the multiple laser spots increase or decrease sequentially.

[0011] Furthermore, the multi-laser spot processing method for solar cells includes modifying the solar cell, wherein the energy of multiple laser spots is the same or increases sequentially, and the size of multiple laser spots is equal or decreases sequentially.

[0012] Furthermore, the multi-laser spot processing method for solar cells includes ablating the solar cell film layer, wherein the energy of multiple laser spots is the same or decreases, and the size of multiple laser spots is the same.

[0013] Furthermore, the multi-laser spot processing method for solar cells includes laser selective doping of the solar cell, comprising: multiple laser spots having energies greater than or equal to 20 μJ and less than or equal to 100 μJ, and the energies of the multiple laser spots being the same or increasing sequentially; when the energies of the multiple laser spots increase sequentially, the energy increment between two adjacent laser spots is 0-50 μJ; the laser spots are square in shape and have a size greater than or equal to 50 μm and less than or equal to 300 μm; the spacing between two adjacent laser spots is in the range of 0 μm to 10 μm.

[0014] Furthermore, the multi-laser spot processing method for solar cells includes laser back passivation ablation treatment of PERC cells, comprising: multiple laser spots with energies greater than or equal to 4 μJ and less than or equal to 25 μJ, and the energies of the multiple laser spots being the same or decreasing sequentially; when the energies of the multiple laser spots decrease sequentially, the energy reduction between two adjacent laser spots is 0-7 μJ; the shape of the laser spots is circular with a diameter greater than or equal to 20 μm and less than or equal to 50 μm; the spacing between two adjacent laser spots is in the range of 0 μm to 10 μm.

[0015] According to another aspect of the present invention, a multi-laser spot processing apparatus for solar cells is provided. The multi-laser spot processing apparatus for solar cells implements the aforementioned multi-laser spot processing method for solar cells. The multi-laser spot processing apparatus for solar cells sequentially includes a laser generating system, a beam splitting system, and a scanning focusing system. The laser generating system emits a laser beam. The beam splitting system receives the laser beam emitted by the laser generating system and splits the laser beam into multiple beams, wherein the energy of the multiple laser beams is all the same, partially the same, or all different. The scanning focusing system receives the multiple laser beams from the beam splitting system and forms multiple laser spots arranged in a straight line on the substrate to be processed. The energy of the multiple laser spots is all the same, partially the same, or all different. The multiple laser spots are scanned and processed according to a set speed and scanning direction, wherein the scanning direction is consistent with the arrangement direction of the multiple laser spots, so that the multiple laser spots sequentially reach the same processing position.

[0016] Furthermore, the laser generating system uses a laser with a wavelength greater than or equal to 355nm and less than or equal to 1064nm, and a power greater than or equal to 10W and less than or equal to 1000W.

[0017] Furthermore, the beam splitting system is a diffractive optical device.

[0018] Furthermore, the scanning focusing system consists of a galvanometer and a field lens.

[0019] Multi-laser spot processing method for solar cells

[0020] According to the technical solution of the present invention, the multi-laser spot processing method for solar cells includes: the laser beam emitted by the laser generating system is split and focused to form multiple laser spots arranged in a straight line on the substrate to be processed, and the energy of the multiple laser spots is all the same, partially the same, or all different; the laser spots are scanned and processed according to a set speed and scanning direction, wherein the scanning direction is consistent with the arrangement direction of the multiple laser spots, so that the multiple laser spots arrive at the same processing position in sequence.

[0021] A multi-laser spot processing method for solar cells involves a laser beam emitted by a laser generator system. After beam splitting and focusing, multiple laser spots are formed on the substrate to be processed, arranged in a straight line. These laser spots may have identical, partially identical, or completely different energies. This configuration allows a single laser beam to be split and focused into multiple beams, which are then projected onto the substrate to form multiple linearly aligned laser spots. This multi-laser scanning processing method saves processing time and increases actual production capacity. Furthermore, since the energies of the multiple laser spots can be identical, partially identical, or completely different, the energy of the laser spots can be adjusted for different solar cell processing technologies to achieve different processing effects. In photovoltaic applications, this method enables the secondary development of processes such as laser heavy doping and laser ablation, improving processing efficiency and results. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0023] Figure 1 A schematic diagram of the structure of a multi-laser spot processing device used in a multi-laser spot processing method for solar cells according to an optional embodiment of the present invention is shown.

[0024] Figure 2 A schematic diagram of multiple laser spots of the same energy according to the present invention is shown;

[0025] Figure 3 This diagram illustrates the effect of multiple circular laser spots with the same energy according to the present invention.

[0026] Figure 4 This diagram illustrates the effect of multiple square laser spots with the same energy according to the present invention.

[0027] Figure 5 A schematic diagram of multiple laser spots with gradient energy according to the present invention is shown;

[0028] Figure 6 A schematic diagram showing multiple laser spots and scanning trajectories with gradient energy is presented;

[0029] Figure 7 This diagram illustrates the scanning process of multiple laser spots with gradient energy during solar cell fabrication.

[0030] Figure 8 The graphs showing the surface concentration versus junction depth obtained by selective doping with multiple laser spots in this application and selective doping with a single laser spot in Example 1 are illustrated.

[0031] The above figures include the following reference numerals:

[0032] 10. Laser generating system; 20. Beam expanding system; 30. Beam splitting system; 40. Scanning and focusing system; 50. Processing platform; 60. Substrate to be processed. Detailed Implementation

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0035] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0036] To address the problems of low efficiency and poor process adaptability in existing multi-laser spot processing methods for solar cells, this invention provides a multi-laser spot processing method and apparatus for solar cells.

[0037] like Figures 1 to 8 As shown, the multi-laser spot processing method for solar cells includes: the laser beam emitted by the laser generating system 10 is split and focused to form multiple laser spots arranged in a straight line on the substrate 60 to be processed; the energy of the multiple laser spots is all the same, partially the same, or all different; the laser spots are scanned and processed according to a set speed and scanning direction, wherein the scanning direction is consistent with the arrangement direction of the multiple laser spots, so that the multiple laser spots arrive at the same processing position in sequence.

[0038] Regarding the setting speed, those skilled in the art will know that controlling the scanning speed makes the repetition rate of a single laser spot zero or slightly greater than zero (i.e., the scanning trajectories of a laser spot have edges that are connected or slightly overlap).

[0039] Specifically, the laser beam emitted by the laser generating system 10 is split and focused to form multiple laser spots on the substrate 60 to be processed. The energy of these multiple laser spots may be all the same, partially the same, or all different. This configuration allows a single laser beam to be split and focused into multiple laser beams, which then illuminate the substrate 60 to form multiple laser spots arranged in a straight line. This allows multiple laser spots to process the substrate 60, achieving a multi-laser-spot scanning processing method. This saves laser processing time and increases actual production capacity. Furthermore, since the energy of the multiple laser spots can be all the same, partially the same, or all different, the energy of the laser spots can be adjusted for different solar cell processing technologies to achieve different processing effects. In photovoltaic applications, this enables the secondary development of laser selective doping processes, laser ablation, and other processes, improving processing efficiency and results.

[0040] It should be noted that the substrate 60 to be processed is a solar cell or a semi-finished silicon wafer. The substrate 60 to be processed can also be a thin sheet or small sheet of crystalline or solid materials such as silicon, sapphire, SiC, GaN, or a silicon cell, thin film cell, perovskite tandem cell, metal and ceramic substrate workpiece.

[0041] Specifically, in the multi-laser spot processing method for solar cells of this application, the multiple laser spots can be the same or different in size. That is to say, the size and energy of the laser spots can be the same or different, so that the multi-laser spot processing method for solar cells can be applied to various photovoltaic processing conditions.

[0042] like Figures 2 to 5 As shown, among the multiple laser spots obtained after the laser beam emitted by the laser generating system 10 is split and focused: the multiple laser spots are all the same size and energy; or the multiple laser spots are the same size but have different energies; or the multiple laser spots are different sizes but have the same energy; or the multiple laser spots are different sizes but have different energies.

[0043] Specifically, when the energies of multiple laser spots are all different, it is preferable that the energies of the multiple laser spots change in a gradient. The gradient change here can be either increasing or decreasing sequentially, and can be selected according to the process requirements.

[0044] Optionally, the laser beam emitted by the laser generating system 10, after being split and focused, yields multiple laser spots: the shape of the multiple laser spots includes one of the following: circular, rectangular, or square; the size of the multiple laser spots ranges from 6 μm to 500 μm; and the spacing between two adjacent laser spots ranges from 0 μm to 10 μm. By reasonably constraining the shape, size, and spacing of the laser spots, it is possible to apply them to solar cell processing technology, while also helping to ensure the accuracy of laser processing.

[0045] Specifically, in the laser beam emitted by the laser generating system 10, after splitting and focusing, multiple laser spots are obtained. For different processes, such as selective doping and other modification processes, a portion of these laser spots are used as the first spot for pre-processing the substrate 60 to be processed; another portion is used as the second spot for processing the substrate 60. The energy of the first spot is lower than that of the second spot, thereby reducing damage to the substrate 60 caused by laser doping and other modifications. The processing trajectories (scanning paths) of the first and second spots coincide, and preferably, the size of the first spot is larger than that of the second spot to improve the processing effect. For processes such as laser ablation, multiple laser spots of the same size and energy are used sequentially along the same path for processing, with multiple passes of lower energy to avoid laser damage during processing. Alternatively, more preferably, the energy of the multiple laser spots decreases sequentially, which helps to reduce laser damage.

[0046] like Figure 1 As shown, a multi-laser spot processing apparatus for solar cells is provided, and a multi-laser spot processing method for solar cells is implemented. Of course, this apparatus is not limited to this one, and adjustments and selections can be made according to actual conditions. The multi-laser spot processing apparatus for solar cells includes a laser generation system 10, a beam splitting system 30, and a scanning focusing system 40.

[0047] The laser generating system 10 emits a laser beam; the beam splitting system 30 receives the laser beam emitted by the laser generating system 10 and splits it into multiple beams, with the energy of the multiple laser beams being all the same, partially the same, or all different. Optionally, the multiple laser beams are shaped and split to form multiple circular, square, or rectangular laser spots; the scanning and focusing system 40 receives the multiple laser beams from the beam splitting system 30 and forms multiple circular, square, or rectangular laser spots arranged in a straight line on the substrate 60 to be processed. The energy of the multiple laser spots is all the same, partially the same, or all different, and their sizes are all the same, partially the same, or all different. The multiple laser spots are scanned and processed according to a set speed and scanning direction, wherein the scanning direction is consistent with the arrangement direction of the multiple laser spots, so that the multiple laser spots arrive at the same processing position one after another, and the multiple laser spots irradiating the substrate 60 to be processed move along the extension direction of the pattern to be processed to complete the scanning and processing of the substrate 60.

[0048] Optionally, the laser generating system 10 includes a laser, which can be a continuous or pulsed laser. The laser can be a laser with a wavelength greater than or equal to 355 nm and less than or equal to 1064 nm and a power greater than or equal to 10 W and less than or equal to 1000 W as the laser generating system 10.

[0049] Specifically, as an implementable method, the beam splitting system 30 is a diffractive optical device (DOE) that splits the laser beam. More preferably, the laser beam is split and shaped to divide the laser beam into multiple beams. The multiple laser beams have the same, partially the same, or completely different energies. The multiple laser spots have the same, partially the same, or completely different sizes, and the shapes of the multiple laser spots are circular, square, or rectangular.

[0050] The scanning and focusing system 40 includes a galvanometer and a field mirror to complete the scanning and focusing of the laser beam.

[0051] like Figure 1 As shown, the multi-laser spot processing device for solar cells also includes a processing platform 50, which is used to support the substrate 60 to be processed.

[0052] The multi-laser spot processing device for solar cells also includes a beam expansion system 20, which is located between the laser generation system 10 and the beam splitting system 30. The beam expansion system 20 is a beam expander, which can be an electric beam expander.

[0053] like Figure 1 As shown, the multi-laser spot processing apparatus for solar cells of this application provides a multi-laser spot processing scheme for solar cells. In the application, the substrate 60 to be processed is placed on the processing platform 50. The laser of the laser generating system 10 emits a single laser beam, which is then split into multiple laser beams after passing through the beam expanding system 20 and the beam splitting system 30. The different energies of each laser beam in the multiple laser beams are obtained by the beam splitting system 30. After the multiple laser beams enter the scanning focusing system 40, multiple laser spots are formed on the substrate 60 to be processed along a straight line. The scanning direction is consistent with the arrangement direction of the multiple laser spots, so that the multiple laser spots arrive at the same processing position one after another. The multiple laser spots irradiating the substrate to be processed move along the extension direction of the pattern to be processed to complete the scanning processing of the substrate 60.

[0054] This application changes the existing single-beam reciprocating scanning processing method. After processing the laser beam with a beam splitting system 30 and a scanning focusing system 40, multiple laser spots with the same or different energies and selectable laser spot sizes are formed along a straight line. Based on the existing single laser beam processing, multi-beam processing is realized while increasing the pretreatment and advancement effect of laser selective doping, which can further improve the selective doping effect and thus improve the conversion efficiency of solar cells. Alternatively, a low-energy multiple processing method is adopted to reduce the damage to the silicon substrate during the ablation of the dielectric film (AlOx / SiNx or SiONx / SiNx, etc.).

[0055] The following description uses selective doping of solar cells / silicon wafers and ablation treatment of solar cells / silicon wafers as examples, but it is not limited to these. Selective doping of solar cells can be extended to other modification processes of solar cells, and ablation treatment of solar cells can be extended to other similar processes such as grooving, ablation, and film removal of solar cell film layers.

[0056] The following section describes the multi-laser spot processing method of this application using selective heavy doping and back passivation ablation processing of solar cells.

[0057] Example 1

[0058] Selective doping (heavy doping / SE) is performed on solar cells / silicon wafers, where the silicon wafer type is not limited to P-type, N-type, etc.

[0059] The laser beam emitted by the laser generating system 10 is split and focused to form multiple laser spots arranged in a straight line on the solar cell. The laser spots may have the same or different energies.

[0060] Multiple laser spots are scanned and processed according to a set speed and scanning direction. The scanning direction is consistent with the arrangement direction of the multiple laser spots, so that the multiple laser spots arrive at the same processing position one after another.

[0061] As those skilled in the art will know, for selective doping, the processing area is the electrode region of the solar cell. A laser spot is used to advance the dopant source, completing the heavy doping of the electrode region. This is prior art and will not be elaborated further here. Regarding the setting speed, those skilled in the art will know that the scanning speed is controlled so that the repetition rate of a single laser spot is zero or slightly greater than zero (i.e., the scanning trajectories of a laser spot have edges that connect or slightly overlap).

[0062] During processing, multiple laser spots are arranged in the same direction as the scanning direction, so that multiple laser spots scan along the length of a region to be processed (linear). The energy of the multiple spots may be the same or different. When the energy is different, the laser spot with lower energy arrives at the same processing position before the laser spot with higher energy, thus completing the processing of a region to be processed.

[0063] Repeat until the scanning and processing of all areas to be processed is completed.

[0064] For selective doping of solar cells, the selective doping area consists of multiple areas to be processed that are spaced apart along the silicon wafer. The scanning process is repeated until all areas to be processed are completed. This means that all areas are scanned sequentially along the same scanning direction.

[0065] Alternatively, the scanning process can be repeated until all areas to be processed are completed: after scanning one area, the arrangement of the laser spots is changed, and the next area to be processed is scanned in the opposite scanning direction. This back-and-forth scanning process is then used to complete the scanning of all areas.

[0066] The laser wavelength of the laser is greater than or equal to 355nm and less than or equal to 1064nm, with the preferred laser wavelength being 532nm.

[0067] The laser spot is preferably square in shape, with a size greater than or equal to 50 μm and less than or equal to 300 μm. More preferably, it is 70–120 μm, more preferably 85–120 μm, but other intermediate ranges or values ​​are also possible. The size of the laser spot is related to the width of the area to be processed, and the laser spot size is equal to or slightly larger than the width of the area to be processed.

[0068] The number of laser spots is two or more, preferably two to six, more preferably two to four, or other intermediate ranges or values. The energy of the laser spots is greater than or equal to 20 μJ and less than or equal to 100 μJ, preferably greater than or equal to 20 μJ and less than or equal to 80 μJ, more preferably greater than or equal to 20 μJ and less than or equal to 50 μJ, or other intermediate ranges or values.

[0069] Preferably, the energy of the multiple laser spots increases sequentially.

[0070] Among the multiple laser spots, the increment between two adjacent laser spots is 0 to 50 μj, more preferably 0 to 30 μj, but other intermediate ranges or values ​​are also possible.

[0071] Among them, the distance between any two adjacent laser spots in the plurality of laser spots is in the range of 0 μm to 10 μm, preferably 0 μm to 7 μm, and more preferably 3-5 μm.

[0072] The following uses three laser spots as an example for illustration. See [link / reference]. Figure 5 and Figure 6 The three laser spots are laser spot 303, laser spot 302 and laser spot 301. The energy of laser spot 303 is 20 μJ, the energy of laser spot 302 is 30 μJ and the energy of laser spot 301 is 50 μJ.

[0073] The size of laser spot 301, laser spot 302 and laser spot 303 is 110μm.

[0074] In this embodiment, at least one of the three laser spots is a first spot (laser spot 303) as a pre-processing laser spot, which serves as a preheating function, and at least one of the spots set after the first spot is a second spot as a propulsion laser spot.

[0075] Here, the first and second laser spots refer only to the doping process. The energy of the first laser spot is lower than that of the second laser spot. The first laser spot reaches a certain processing position first and plays a role in pretreatment and activation. The second laser spot has higher energy and plays a role in promoting doping after activation. It does not refer to a specific laser spot.

[0076] In a preferred embodiment, the size of the first light spot is larger than the size of the second light spot. Preferably, the size of the first light spot is 120 μm and the size of the second light spot is 100 μm. This configuration increases the activation range, allowing for more uniform doping after activation.

[0077] like Figure 7 As shown, a schematic diagram of scanning back and forth using three laser spots is presented. The scanning direction is from weak to strong energy distribution of multiple laser spots. When processing the second row, the diffraction optical device is rotated 180° so that the energy distribution of the three laser spots is exactly opposite to that of the three laser spots in the first row.

[0078] Of course, the energy of the three laser spots mentioned above can also be the same. The scanning processing method of three laser spots with the same energy is the same as the processing method mentioned above, but the processing effect is slightly worse, which will not be elaborated here.

[0079] This embodiment reduces the energy used by the doping laser while achieving the same doping effect. On the other hand, reducing the laser energy can effectively reduce damage to the silicon substrate, thereby improving the conversion efficiency of the silicon wafer.

[0080] Table 1 shows the comparison data between this embodiment and the existing single-laser spot doping effect:

[0081]

[0082] Table 1

[0083] The difference between the aforementioned prior art used for comparison is that its doped optical path is a single laser spot, wherein the laser spot has a size of 110μm*110μm, a single pulse energy of 100μj, and a sheet resistance of 64Ω in one engraving scan.

[0084] The laser spot size of this application is 110*110μm, and the energies of the three laser spots are 20μJ, 30μJ and 50μJ respectively.

[0085] like Figure 8As shown, ECV testing revealed that the surface concentration, doping source distribution curve, and junction depth obtained by multi-laser spot doping in this application are basically the same as those obtained by existing single-laser spot doping.

[0086] This invention minimizes thermal damage to silicon substrates caused by laser light by reducing the energy of a single laser spot and utilizing a pre-treatment of the first laser spot followed by effective doping of the second laser spot. Electrical performance comparison tests show that the SE solar cell using the multi-laser spot heavy doping technology of this invention achieves a conversion efficiency of 22.36%, an improvement of 0.07% compared to traditional SE solar cells. This improvement is mainly due to the increased open-circuit voltage, indicating that the doping of multiple low-energy laser spots significantly reduces laser thermal damage.

[0087] Example 2

[0088] Ablation treatment is performed on solar cells / silicon wafers, where the silicon wafer type is not limited to P-type, N-type, etc. Ablation includes back passivation grooving of PERC cells, and can also be performed on other dielectric films.

[0089] The following describes the back passivation grooving process for PERC cells.

[0090] The laser beam emitted by the laser generating system 10 is split and focused to form multiple laser spots arranged in a straight line on the solar cell. The multiple laser spots may have the same or different energies.

[0091] Multiple laser spots are scanned and processed according to a set speed and scanning direction. The scanning direction is consistent with the arrangement direction of the multiple laser spots, so that the multiple laser spots arrive at the same processing position one after another.

[0092] As those skilled in the art will know, for the back passivation trenching of PERC cells, the trenching area consists of multiple processing areas spaced along the silicon wafer, which is existing technology and will not be described in detail here.

[0093] During processing, the arrangement direction of multiple laser spots is consistent with the scanning direction, so that multiple laser spots scan along the length of a processing area (linear). The energy of the multiple laser spots may be the same or different. When the energy is different, the laser spot with higher energy arrives at the same processing position before the laser spot with lower energy, thus completing the processing of a processing area.

[0094] Repeat until the scanning and processing of all areas to be processed is completed.

[0095] For the back passivation grooving process of PERC cells, the grooving area consists of multiple areas to be processed spaced along the silicon wafer. The scanning process is repeated until all areas to be processed are completed: all areas are scanned sequentially along the same scanning direction. Regarding the setting speed, those skilled in the art will know that the scanning speed is controlled so that the repetition rate of a single laser spot is zero or slightly greater than zero (i.e., the scanning trajectories of a laser spot have edges that are connected or slightly overlap).

[0096] Alternatively, the scanning process can be repeated until all areas to be processed are completed: after scanning one area, the arrangement of the laser spots is changed, and the next area to be processed is scanned in the opposite scanning direction. This back-and-forth scanning process is then used to complete the scanning of all areas.

[0097] The laser wavelength of the laser is equal to 355 nanometers and less than or equal to 1064 nanometers, with a preferred laser wavelength of 532 nm.

[0098] The laser spot is circular in shape, with a diameter greater than or equal to 20 μm and less than or equal to 50 μm. Preferably, it is 25–40 μm, more preferably 25–30 μm, but other intermediate ranges or values ​​are also possible. The size of the laser spot is related to the width of the area to be processed; preferably, the diameter of the laser spot is not greater than the width of the area to be processed.

[0099] The number of laser spots is 2 or more, preferably 2 to 6, more preferably 2 to 4, or other intermediate ranges or values. The energy of each laser spot is greater than or equal to 4 μJ and less than or equal to 25 μJ, preferably greater than or equal to 4 μJ and less than or equal to 15 μJ, more preferably greater than or equal to 4 μJ and less than or equal to 10 μJ, or other intermediate ranges or values.

[0100] Preferably, the energy of the multiple laser spots decreases sequentially.

[0101] Among the multiple laser spots, the decrease in the value between two adjacent laser spots is 0 to 10 μj, more preferably 0 to 5 μj, but it can also be other intermediate ranges or values.

[0102] Among the multiple laser spots, the distance between any two adjacent laser spots is in the range of 0μm to 10μm, preferably 0μm to 7μm, more preferably 3-5μm, or other intermediate ranges or values.

[0103] The following description uses three laser spots as an example. The three laser spots are all the same size, with a diameter of 30 μm. The energies of the three laser spots are 10 μJ, 8 μJ, and 4 μJ, respectively, and the distance between any two adjacent laser spots is 3 μm.

[0104] Of course, the energy of the three laser spots mentioned above can also be the same. The scanning processing method of three laser spots with the same energy is the same as the processing method mentioned above, but the processing effect is slightly worse, which will not be elaborated here.

[0105] This solution, while achieving the same surface ablation effect, effectively reduces damage to the silicon substrate by reducing the energy used in a single laser pulse and performing laser processing multiple times at the same location, thereby improving its conversion efficiency.

[0106] Table 2 shows the comparison data of the single-laser processing effect of this embodiment with that of existing single-laser spot single-shot laser processing:

[0107] type Eta / % Voc / mV <![CDATA[Jsc / mA / cm 2 ]]> FF / % Existing single-laser spot ablation 22.396 684.3 41.81 78.28 This application involves multi-laser spot ablation. 22.419 684.4 41.83 78.31

[0108] Table 2

[0109] The existing single laser spot size is 30μm and the single pulse energy is 18μJ; the multi-laser spot size is 30μm, and their energies are 10μJ, 8μJ and 4μJ respectively.

[0110] This invention reduces the energy of a single laser spot and utilizes a multi-beam laser processing method to minimize thermal damage to the silicon substrate caused by the laser. Electrical performance comparison tests show that the multi-laser ablation technology in this invention achieves a solar cell conversion efficiency of 22.419%, which is 0.023% higher than the efficiency of traditional single-laser spot laser ablation solar cells. This is mainly reflected in slight improvements in Voc, Jsc, and FF, indicating that multiple low-energy ablation methods significantly reduce laser thermal damage.

[0111] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0112] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0113] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0114] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for processing multiple laser spots in solar cells, characterized in that, include: The laser beam emitted by the laser generating system (10) is split and focused to form multiple laser spots arranged in a straight line on the substrate (60) to be processed. The energy of the multiple laser spots is all the same, partially the same, or all different; the size and energy of the multiple laser spots are the same; or the size of the multiple laser spots is the same but the energy is different; or the size of the multiple laser spots is different but the energy is the same; or the size of the multiple laser spots is different but the energy is different. The laser spot is scanned and processed according to a set speed and scanning direction, wherein the scanning direction is consistent with the arrangement direction of the multiple laser spots, so that the multiple laser spots arrive at the same processing position in sequence; the multi-laser spot processing method for the solar cell involves modifying, doping, or ablating the solar cell film layer; When the multi-laser spot processing method for the solar cell is to modify the solar cell, the energy of the multiple laser spots is the same or increases, and the size of the multiple laser spots is equal or decreases. When the multi-laser spot processing method for the solar cell involves ablating the solar cell film layer, the energy of the multiple laser spots is the same or decreases sequentially, and the size of the multiple laser spots is the same. When the multi-laser spot processing method for the solar cell involves laser selective doping of the cell, the energy of the multiple laser spots is greater than or equal to 20 μJ and less than or equal to 100 μJ, and the energy of the multiple laser spots is the same or increases sequentially; when the energy of the multiple laser spots increases sequentially, the energy increment between two adjacent laser spots is 0-50 μJ; the shape of the laser spots is square and the size is greater than or equal to 50 μm and less than or equal to 300 μm; the spacing between two adjacent laser spots is in the range of 0 μm to 10 μm.

2. The multi-laser spot processing method for solar cells according to claim 1, characterized in that, The multiple laser spots may be the same size or different sizes.

3. The multi-laser spot processing method for solar cells according to claim 1, characterized in that, Among the multiple laser spots obtained after the laser beam emitted by the laser generating system (10) is split and focused: The shape of the plurality of laser spots includes one of circles, rectangles and squares; the size of the plurality of laser spots is in the range of 6 μm to 500 μm; the distance between two adjacent laser spots is in the range of 0 μm to 10 μm; and the number of the plurality of laser spots is 2 to 6.

4. The multi-laser spot processing method for solar cells according to claim 1, characterized in that, When the energies of the multiple laser spots are all different, the energies of the multiple laser spots increase or decrease.

5. The multi-laser spot processing method for solar cells according to claim 1, characterized in that, The multi-laser spot processing method for solar cells includes laser back passivation ablation treatment of PERC cells, including: The energy of the plurality of laser spots is greater than or equal to 4 μJ and less than or equal to 25 μJ, and the energy of the plurality of laser spots is the same or decreases sequentially; When the energy of the multiple laser spots decreases sequentially, the energy reduction between two adjacent laser spots is 0-7 μJ; The laser spot is circular in shape and has a diameter greater than or equal to 20 μm and less than or equal to 50 μm; The spacing between two adjacent laser spots in the plurality of laser spots is in the range of 0 μm to 10 μm.

6. A multi-laser spot processing device for solar cells, characterized in that, The method for processing solar cells using the multi-laser spot processing device of the solar cells according to any one of claims 1 to 5 is implemented. The multi-laser spot processing device of the solar cells includes, in sequence, a laser generation system (10), a beam splitting system (30), and a scanning focusing system (40). The laser generating system (10) emits a laser beam; The beam splitting system (30) receives the laser beam emitted by the laser generating system (10) and splits the laser beam into multiple beams, wherein the energy of the multiple laser beams is all the same, partially the same, or completely different. The scanning focusing system (40) is used to receive multiple laser beams from the beam splitting system (30) and form multiple laser spots arranged in a straight line on the substrate (60) to be processed. The energy of the multiple laser spots is all the same, partially the same, or all different. The multiple laser spots are scanned and processed according to a set speed and scanning direction. The scanning direction is consistent with the arrangement direction of the multiple laser spots so that the multiple laser spots arrive at the same processing position in sequence.

7. The multi-laser spot processing apparatus for solar cells according to claim 6, characterized in that, The laser generating system (10) uses a laser with a wavelength greater than or equal to 355nm and less than or equal to 1064nm, and a power greater than or equal to 10W and less than or equal to 1000W.

8. The multi-laser spot processing apparatus for solar cells according to claim 6, characterized in that, The beam splitting system (30) is a diffractive optical device.

9. The multi-laser spot processing apparatus for solar cells according to claim 6, characterized in that, The scanning focusing system (40) consists of a galvanometer and a field lens.

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