CN116174889A

CN116174889A - Multi-laser-spot processing method and processing device for solar cell

Info

Publication number: CN116174889A
Application number: CN202111426144.XA
Authority: CN
Inventors: 张松; 朱俊; 黄海平; 陆红艳; 朱凡
Original assignee: Dier Laser Technology Wuxi Co ltd
Current assignee: Dier Laser Technology Wuxi Co ltd
Priority date: 2021-11-26
Filing date: 2021-11-26
Publication date: 2023-05-30

Abstract

The invention provides a multi-laser-spot processing method and a processing device for a solar cell. The multi-laser-spot processing method of the solar cell comprises the following steps: after being split and focused, the laser beam emitted by the laser generating system forms a plurality of laser spots which are arranged along a straight line on a substrate to be processed, and the energy of the plurality of laser spots is the same, partially the same or totally different; and scanning the laser spots according to the set speed and the 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 sequentially reach the same processing position. The invention solves the problems of poor efficiency and poor process adaptability of the multi-laser spot processing method of the solar cell in the prior art.

Description

Multi-laser-spot processing method and processing device for solar cell

Technical Field

The invention relates to the technical field of laser precision machining equipment, in particular to a multi-laser-spot machining method and device for a solar cell.

Background

With the development of technology, the solar cell industry technology is very mature. The cost reduction and efficiency enhancement are always the targets of the solar cell industry. With the continuous development of photovoltaic technology, solar cell back passivation technology, selective doping technology, component half-sheet technology and the like gradually become standard technology of production lines.

In the current technology of solar cell back passivation, selective emitter, half-sheet and the like, laser is used as one of the indispensable tools in the production line.

The existing laser processing method of the solar cell in the solar cell industry generally adopts a single laser beam single scanning head reciprocating scanning processing mode, and has the defects that single laser beam single fixed laser energy can only process a certain specific position, if the laser energy needs to be changed according to process requirements, repeated engraving scanning is needed, the laser repeated scanning processing time and the complexity of pattern setting are increased, the processing effect is difficult to ensure, secondary development of the solar cell laser process is limited, and the deep development of laser technology application is not facilitated.

That is, the multi-laser spot processing method of the solar cell in the prior art has the problems of poor efficiency and poor process adaptability.

Disclosure of Invention

The invention mainly aims to provide a multi-laser-spot processing method and a processing device for a solar cell, which are used for solving the problems of poor efficiency and poor process adaptability of the multi-laser-spot processing method for the solar cell in the prior art.

In order to achieve the above object, according to one aspect of the present invention, there is provided a multi-laser spot processing method of a solar cell, comprising: after being split and focused, the laser beam emitted by the laser generating system forms a plurality of laser spots which are arranged along a straight line on a substrate to be processed, and the energy of the plurality of laser spots is the same, partially the same or totally different; and scanning the laser spots according to the set speed and the 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 sequentially reach the same processing position.

Further, the sizes of the plurality of laser spots are the same or different.

Further, among a plurality of laser spots obtained after the laser beam emitted by the laser generating system is split and focused: the shape of the plurality of laser spots comprises one of a circle, a rectangle and a square; the plurality of laser spots has a size in the range of 6 μm to 500 μm; the distance between two adjacent laser spots in the plurality of laser spots is in the range of 0 μm to 10 μm; the number of the plurality of laser spots is 2 to 6.

Further, when the energies of the plurality of laser spots are all different, the energies of the plurality of laser spots are increased or decreased.

Further, the multi-laser light spot processing method of the solar cell comprises the step of modifying the solar cell, wherein the energy of a plurality of laser light spots is the same or presented to be increased, and the sizes of the plurality of laser light spots are the same or reduced.

Further, the multi-laser-spot processing method of the solar cell comprises the step of ablating a solar cell film layer, wherein the energy of a plurality of laser spots is the same or is gradually reduced, and the sizes of the plurality of laser spots are the same.

Further, the multi-laser spot processing method of the solar cell comprises the steps of performing laser selective doping treatment on the cell, and the method comprises the following steps: the energy of the plurality of laser spots is more than or equal to 20 mu j and less than or equal to 100 mu j, and the energy of the plurality of laser spots is the same or sequentially increases; when the energy of the plurality of laser spots increases in sequence, the increment of the energy of two adjacent laser spots in the plurality of laser spots is 0-50 mu j; the shape of the laser spot is square, and the size of the laser spot is more than or equal to 50 mu m and less than or equal to 300 mu m; the spacing between adjacent two of the plurality of laser spots is in the range of 0 μm to 10 μm.

Further, the method for processing the multiple laser spots of the solar cell comprises the following steps of: the energy of the plurality of laser spots is larger than or equal to 4 mu j and smaller than or equal to 25 mu j, and the energy of the plurality of laser spots is the same or gradually decreases; when the energy of the plurality of laser spots is gradually decreased, the decrease of the energy of two adjacent laser spots in the plurality of laser spots is 0-7 mu j; the shape of the laser spot is circular, and the diameter is more than or equal to 20 mu m and less than or equal to 50 mu m; the spacing between adjacent two of the plurality of laser spots is in the range of 0 μm to 10 μm.

According to another aspect of the present invention, there is provided a multi-laser spot processing apparatus for a solar cell, the multi-laser spot processing apparatus for a solar cell is used to implement the multi-laser spot processing method for a solar cell, and the multi-laser spot processing apparatus for a solar cell 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 beams emitted by the laser generating system and splits the laser beams into a plurality of beams, and the energy among the plurality of beams is the same, partially the same or totally different; the scanning focusing system is used for receiving a plurality of laser beams of the beam splitting system, forming a plurality of laser spots which are arranged along a straight line on a substrate to be processed, wherein the energy among the laser spots is the same, the energy among the laser spots is the same or the energy among the laser spots are 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 laser spots, so that the laser spots sequentially reach the same processing position.

Further, the laser generating system adopts a laser with a laser wavelength of 355nm or more and 1064nm or less and a power of 10W or more and 1000W or less.

Further, the beam splitting system is a diffractive optic.

Further, the scanning focusing system is a galvanometer and a field lens.

Multi-laser-spot processing method of solar cell multi-laser-spot processing method of solar cell

By applying the technical scheme of the invention, the multi-laser-spot processing method of the solar cell comprises the following steps: after being split and focused, the laser beam emitted by the laser generating system forms a plurality of laser spots which are arranged along a straight line on a substrate to be processed, and the energy of the plurality of laser spots is the same, partially the same or totally different; and scanning the laser spots according to the set speed and the 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 sequentially reach the same processing position.

The laser beam emitted by the laser generating system forms a plurality of laser spots which are arranged along a straight line on a substrate to be processed after being split and focused, and the energy of the laser spots is the same, the energy of the laser spots are the same or the energy of the laser spots are different, so that one laser beam forms a plurality of laser beams after being split and focused, and then the laser beams are emitted on the substrate to be processed to form a plurality of laser spots which are arranged along the straight line, so that the plurality of laser spots process the substrate to be processed, a mode of multi-laser scanning processing is realized, the laser processing time is saved, and the actual productivity is increased. Meanwhile, the energy of the laser light spots can be all the same, partially the same or all different, so that the energy of the laser light spots can be adjusted according to different solar cell processing technologies to achieve different processing effects. The secondary development of the laser heavy doping process, the laser ablation process and the like is realized on the photovoltaic application, the processing efficiency is improved, and the processing effect is improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:

fig. 1 is a schematic structural diagram of a multi-laser spot processing apparatus used in a multi-laser spot processing method of a solar cell according to an alternative embodiment of the present invention;

FIG. 2 shows a schematic of multiple laser spots of the same energy of the present invention;

FIG. 3 shows a schematic diagram of the effect of multiple circular laser spots of the present invention with equal energy;

FIG. 4 shows a schematic diagram of the effect of the present invention on a plurality of square laser spots of equal energy;

FIG. 5 shows a schematic representation of a plurality of laser spots of the present invention having a gradient of energy;

FIG. 6 shows a schematic diagram of a plurality of laser spots and scan trajectories with gradient energy;

FIG. 7 shows a schematic diagram of a plurality of laser spots with energy in a gradient during a scanning process in solar cell processing;

fig. 8 shows a graph of surface concentration versus junction depth for multiple laser spot selective doping and prior single laser spot selective doping of the present application in embodiment one.

Wherein the above figures include the following reference numerals:

10. a laser generating system; 20. a beam expanding system; 30. a beam splitting system; 40. a scanning focusing system; 50. a processing platform; 60. and processing the substrate.

Detailed Description

It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The invention will be described in detail below with reference to the drawings in connection with embodiments.

It is noted that all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs unless otherwise indicated.

In the present invention, unless otherwise indicated, terms of orientation such as "upper, lower, top, bottom" are used generally with respect to the orientation shown in the drawings or with respect to the component itself in the vertical, upright or gravitational direction; also, for ease of understanding and description, "inner and outer" refers to inner and outer relative to the profile of each component itself, but the above-mentioned orientation terms are not intended to limit the present invention.

The invention provides a multi-laser spot processing method and a processing device of a solar cell, aiming at solving the problems of poor efficiency and poor process adaptability of the multi-laser spot processing method of the solar cell in the prior art.

As shown in fig. 1 to 8, the method for processing multiple laser spots of a solar cell includes that laser beams emitted by a laser generating system 10 are split and focused to form a plurality of laser spots arranged along a straight line on a substrate 60 to be processed, and the energy of the plurality of laser spots is all the same, partially the same or all different; and scanning the laser spots according to the set speed and the 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 sequentially reach the same processing position.

With respect to the set speed, those skilled in the art will recognize that the scan speed is controlled such that the repetition rate of a single laser spot is zero or slightly greater (i.e., the scan trajectories of one laser spot are contiguous or slightly coincident at their edges).

Specifically, the laser beam emitted by the laser generating system 10 is split and focused to form a plurality of laser spots on the substrate 60 to be processed, where the energy of the plurality of laser spots is all the same, partially the same, or all different. The arrangement is that a plurality of laser beams are formed after being split and focused, and then a plurality of laser spots which are arranged along a straight line are formed on the substrate 60 to be processed by irradiation, so that the plurality of laser spots process the substrate 60 to be processed, the mode of scanning and processing the plurality of laser spots is realized, the laser processing time is saved, the actual productivity is increased, and meanwhile, the energy of the plurality of laser spots can be all the same, partially the same or all different, so that the energy of the laser spots can be adjusted according to different solar cell processing technologies, and different processing effects can be realized. The secondary development of the laser selective doping process, the laser ablation process and the like is realized on the photovoltaic application, the processing efficiency is improved, and the processing effect is improved.

The substrate 60 to be processed is a solar cell or a semi-finished silicon wafer. The substrate 60 to be processed may also be a thin sheet or a small sheet of crystal or solid material such as silicon, sapphire, siC, gaN, or the like, or a silicon cell, a thin film cell, a perovskite laminate cell, a metal and ceramic substrate work piece.

Specifically, the multiple laser spots in the multiple laser spot processing method of the solar cell have the same or different sizes. That is, the size and energy of the laser spots can be the same or different, so that the multi-laser-spot processing method of the solar cell is suitable for various photovoltaic processing working conditions.

As shown in fig. 2 to 5, the laser beam emitted by the laser generating system 10 is split and focused to obtain a plurality of laser spots: the size and the energy of the laser spots are the same; or a plurality of laser spots with the same size and different energy; or the sizes of the laser spots are different, and the energy is the same; or the laser spots are different in size and energy.

Specifically, when the energy of the plurality of laser spots is all different, it is preferable that the energy of the plurality of laser spots is changed in a gradient, and the gradient change can be sequentially increased or sequentially decreased, and can be selected according to the process requirement.

Optionally, the laser beam emitted by the laser generating system 10 is split and focused to obtain a plurality of laser spots: the shape of the plurality of laser spots comprises one of a circle, rectangle or square; the size of the plurality of laser spots is in the range of 6 μm to 500 μm, and the pitch of two adjacent laser spots in the plurality of laser spots is in the range of 0 μm to 10 μm. The shape, the size and the spacing of the laser spots are reasonably restrained, so that the method is applicable to a solar cell processing technology, and meanwhile, the precision of laser processing is guaranteed.

Specifically, among a plurality of laser spots obtained by splitting and focusing a laser beam emitted from the laser generating system 10: for different processes, such as a modification process of selective doping, a part of laser spots are used as first spots, and the first spots are adopted to pretreat the substrate 60 to be processed; the other part of the laser light spots are used as second light spots, and the second light spots are used for processing the substrate 60 to be processed; wherein, the energy of the first light spot is smaller than that of the second light spot, thereby reducing the damage to the substrate 60 to be processed caused by modification such as laser doping. The first light spot is overlapped with the processing track (scanning path) of the second light spot, and the size of the first light spot is preferably larger than that of the second light spot so as to improve the processing effect. For example, in the laser ablation process, a plurality of laser spots with the same size and energy sequentially pass through the same path for processing, and the laser spots are processed for multiple times with small energy so as to avoid laser damage. Or more preferably, the energy of the plurality of laser spots is sequentially reduced, which is beneficial to reducing laser damage.

As shown in fig. 1, a multi-laser spot processing apparatus for a solar cell is provided, and a multi-laser spot processing method for a solar cell is implemented. The multi-laser spot processing device of the solar cell comprises a laser generating 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 is configured to receive the laser beams emitted by the laser generating system 10, split one laser beam into multiple laser beams, and make the energy among the multiple laser beams identical, partially identical or completely different, and optionally shape and split the multiple laser beams to form multiple round, square or rectangular laser spots; the scanning focusing system 40 is configured to receive the multiple laser beams of the beam splitting system 30, form multiple laser spots on the substrate 60 to be processed, where the multiple laser spots are in a shape of circles, squares or rectangles and are arranged in a straight line, the multiple laser spots are all the same, are all the same or are all different in energy, are all the same or are all the same in size, are all the same or are all the different in part, and perform scanning processing according to a set speed and a scanning direction, where the scanning direction and the arrangement direction of the multiple laser spots are consistent, so that the multiple laser spots sequentially reach the same processing position, and the multiple laser spots irradiated on the substrate 60 to be processed move along the extending direction of the pattern to be processed to complete the scanning processing of the substrate 60 to be processed.

Alternatively, the laser generating system 10 includes a laser, which may be a continuous or pulsed laser, and a laser having a wavelength of 355nm or more and 1064nm or less and a power of 10W or more and 1000W or less may be used as the laser of the laser generating system 10.

Specifically, as an embodiment, the beam splitting system 30 is a diffraction optical Device (DOE), the laser beam is split by using the diffraction optical device, more preferably, the laser beam is split and shaped, the laser beam is split into multiple beams, the energy of the multiple beams is all the same, part of the multiple beams is the same or all different, the sizes of the multiple laser spots are all the same, part of the multiple beams is the same or all different, and the shapes of the multiple laser spots are circular, square or rectangular.

The scanning focusing system 40 includes galvanometer and field lens to perform scanning and focusing of the laser beam.

As shown in fig. 1, the multi-laser spot processing apparatus of the solar cell further includes a processing platform 50, where the processing platform 50 is used to carry a substrate 60 to be processed.

The multi-laser spot processing device of the solar cell further comprises a beam expanding system 20, wherein the beam expanding system 20 is arranged between the laser generating system 10 and the beam splitting system 30, the beam expanding system 20 is a beam expander, and the beam expander can be an electric beam expander.

As shown in fig. 1, the multi-laser-spot processing device for a solar cell of the present application provides a multi-laser-spot processing scheme for a solar cell, in which a substrate 60 to be processed is placed on a processing platform 50 in application, after a single laser beam emitted by a laser generating system 10 passes through a beam expanding system 20 and a beam splitting system 30, the single laser beam is split into multiple laser beams, wherein different energies of each laser beam in the multiple laser beams are obtained by using the beam splitting system 30, after the multiple laser beams enter a scanning focusing system 40, multiple laser spots arranged along a straight line are formed on the substrate 60 to be processed, 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, and the multiple laser spots irradiated on the substrate to be processed move along the extending direction of a pattern to be processed to finish the scanning processing of the substrate 60 to be processed.

The laser beam processing method changes the existing laser single-beam reciprocating scanning processing mode, and after the laser beams are processed by the beam splitting system 30 and the scanning focusing system 40, a plurality of laser spots with the same or different energy and the same or different optional laser spot size which are arranged along a straight line are formed, and on the basis of the existing single-beam processing, the pretreatment and the propelling effects of laser selective doping are increased while the multi-beam processing is realized, and the selective doping effect can be further improved, so that the conversion efficiency of the solar cell is improved; or, the damage to the silicon substrate in the ablation of the dielectric film (AlOx/SiNx or SiOx/SiNx and the like) is reduced by adopting a low-energy multi-time processing mode.

The following description will be given by taking the example of selectively doping the solar cell/silicon wafer and ablating the solar cell/silicon wafer, but the invention is not limited thereto, and the selective doping of the solar cell can be extended to other processes such as modifying the solar cell, and the ablating of the solar cell can be extended to other processes such as slotting, ablating, and stripping the solar cell film.

The multi-laser-spot processing method of the application is described below in terms of selective heavy doping and back passivation ablation processing of solar cells.

Example 1

The solar cell/wafer is subjected to selective doping (heavy doping/SE) processing, wherein the wafer type is not limited to P-type, N-type, etc.

The laser beam emitted by the laser generating system 10 forms a plurality of laser spots which are arranged along a straight line on the solar cell after being split and focused, and the energy among the plurality of laser spots is the same or different;

and the plurality of laser spots are scanned and processed according to the set speed and the 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 sequentially reach the same processing position.

As can be known by those skilled in the art, for the selective doping, the processing area is an electrode area of the solar cell, and the laser spot is used to push the doping source to complete the heavy doping of the electrode area. With respect to the set speed, those skilled in the art will recognize that the scan speed is controlled such that the repetition rate of a single laser spot is zero or slightly greater (i.e., the scan trajectories of one laser spot are contiguous or slightly coincident at their edges).

When processing, the arrangement direction and the scanning direction of the laser spots are consistent, so that the laser spots scan along the length direction of an area to be processed (line shape), wherein the energy among the laser spots is the same or different, and when the energy is different, the laser spot with small energy reaches the same processing position before the laser spot with large energy, so that the processing of the area to be processed is completed;

repeating until the scanning processing of all the areas to be processed is completed.

For the selective doping processing of the solar cell, the selective doping regions are a plurality of to-be-processed regions which are arranged at intervals along the silicon wafer, and the scanning processing is repeated until all to-be-processed regions are completed, wherein the scanning processing comprises the following steps: and scanning all the areas along the same scanning direction.

Or repeating the scanning processing until all the areas to be processed are finished: after the scanning of one area to be processed is completed, the arrangement sequence of each laser spot is changed, and the scanning of the next area to be processed is completed along the opposite scanning direction, so that the scanning processing of all areas is completed by back and forth scanning.

Wherein the laser wavelength of the laser is 355nm or more and 1064nm or less, and the preferred laser wavelength is 532nm.

Wherein the shape of each laser spot is preferably square, and the size is 50 μm or more and 300 μm or less. Preferably 70 to 120. Mu.m, more preferably 85 to 120. Mu.m, and may be in other intermediate ranges or values. The size of the laser spot is related to the width of the area to be processed, and the size of the laser spot is equal to or slightly larger than the width of the area to be processed.

The number of the plurality of laser spots is 2 or more, preferably 2 to 6, more preferably 2 to 4, and may be other intermediate ranges or values. The energy of the plurality of laser spots is 20 μj or more and 100 μj or less, preferably 20 μj or more and 80 μj or less, more preferably 20 μj or more and 50 μj or less, or may be in other intermediate ranges or values.

Preferably, the energy of the plurality of laser spots increases sequentially.

The increment of two adjacent laser spots in the plurality of laser spots is 0-50 mu j, more preferably 0-30 mu j, and can be other intermediate ranges or values.

Wherein the spacing between any adjacent two of the plurality of laser spots is in the range of 0 μm to 10 μm, preferably 0 μm to 7 μm, more preferably 3-5 μm.

In the following, three laser spots are described as an example, referring to fig. 5 and 6, where the three laser spots are a laser spot 303, a laser spot 302 and a laser spot 301, respectively, the energy of the laser spot 303 is 20 μj, the energy of the laser spot 302 is 30 μj, and the energy of the laser spot 301 is 50 μj.

The laser spot 301, the laser spot 302 and the laser spot 303 are each 110 μm in size.

In this embodiment, at least one of the three laser spots is a first spot (laser spot 303) serving as a preprocessing laser spot, which plays a role in preheating, and at least one of the spots disposed behind the first spot is a second spot serving as a propelling laser spot.

Here, the energy of the first light spot is lower than that of the second light spot only for doping technology, the first light spot reaches a certain processing position first to play a role in pretreatment and activation, the second light spot is higher in energy to play a role in doping and propelling after activation, and a certain laser light spot is not specified.

As a preferred embodiment the size of the first spot is larger than the size of the second spot, preferably the size of the first spot is 120 μm and the size of the second spot is 100 μm. The advantage of this arrangement is that the activation range is increased, and the doping promotion after activation can be more uniform.

As shown in fig. 7, a schematic diagram of back and forth scanning with three laser spots is used, the scanning direction is that the energy distribution of multiple laser spots is from weak to strong, wherein the diffraction optics are rotated 180 ° when the second row is processed, so that the energy distribution of the three laser spots is exactly opposite to the energy distribution of the three laser spots of the first row.

Of course, the energy of the three laser spots may be the same, and the scanning processing mode of the three laser spots with the same energy is the same as the processing mode, but the processing effect is slightly poorer, and the description is omitted here.

On the one hand, the embodiment reduces the energy used by the doped laser on the premise of achieving the same doping effect; on the other hand, the damage to the silicon substrate can be effectively reduced by reducing the laser energy, and the conversion efficiency of the silicon wafer is further improved.

The comparative data of doping effect of the present embodiment and the existing single laser spot are shown in table 1:

TABLE 1

The difference between the above-mentioned prior art for comparison is that the doping light path is a single laser spot, wherein the laser spot has a size of 110 μm×110 μm, the single pulse energy is 100 μj, and the sheet resistance is reduced to 64Ω by one engraving scan.

The size of the laser spots is 110 x 110 mu m, and the energy of the three laser spots is 20 mu j, 30 mu j and 50 mu j respectively.

As shown in fig. 8, through ECV test, the multi-laser-spot doping of the present application is substantially the same as the surface concentration, doping source distribution curve and junction depth obtained by the existing single-laser-spot doping.

According to the invention, the heat damage of the laser to the silicon substrate can be reduced to the greatest extent by reducing the energy of a single laser spot and utilizing the modes of pretreatment of the first light spot and effective doping of the second light spot. The electrical performance contrast test shows that: the conversion efficiency of the SE solar cell with the multi-laser-spot heavy doping technology reaches 22.36%, and the efficiency is improved by 0.07% compared with the traditional SE solar cell; the method mainly aims at improving open-circuit voltage, and shows that doping of low-energy laser spots for multiple times has obvious improvement effect on laser thermal damage.

Example two

And (3) performing ablation treatment on the solar cell/silicon wafer, wherein the type of the silicon wafer is not limited to P type, N type and the like, and the ablation comprises back passivation slotting of the PERC cell and can also be ablation of other dielectric films and the like.

The following description is made with respect to the back passivation slotting process of the PERC cell.

The laser beam emitted by the laser generating system 10 forms a plurality of laser spots which are arranged along a straight line on the solar cell after being split and focused, and the energy of the plurality of laser spots is the same or different;

Those skilled in the art can know that, for the back passivation slotting of the PERC battery, the slotting areas are a plurality of to-be-processed areas arranged along the silicon wafer at intervals, which is the prior art and will not be described herein.

When processing, the arrangement direction and the scanning direction of the laser spots are consistent, so that the laser spots scan along the length direction of an area to be processed (line shape), wherein the energy among the laser spots is the same or different, and when the energy is different, the laser spot with high energy reaches the same processing position before the laser spot with low energy, so that the processing of the area to be processed is completed;

For the back passivation grooving processing of the PERC battery, the grooving areas are a plurality of areas to be processed which are arranged at intervals along a silicon wafer, and the scanning processing is repeated until all the areas to be processed are completed, wherein the scanning processing is as follows: and scanning all the areas along the same scanning direction. With respect to the set speed, those skilled in the art will recognize that the scan speed is controlled such that the repetition rate of a single laser spot is zero or slightly greater (i.e., the scan trajectories of one laser spot are contiguous or slightly coincident at their edges).

Wherein the laser wavelength of the laser is 355nm and less than or equal to 1064nm, and the preferred laser wavelength is 532nm.

Wherein the laser spot is circular in shape, and has a diameter of 20 μm or more and 50 μm or less. Preferably 25 to 40. Mu.m, more preferably 25 to 30. Mu.m, and may be in other intermediate ranges or values. The size of the laser spot is related to the width of the area to be processed, and preferably the laser spot diameter is not larger than the width of the area to be processed.

The number of the plurality of laser spots is 2 or more, preferably 2 to 6, more preferably 2 to 4, but may be other intermediate ranges or values. The energy per laser spot is not less than 4 μj and not more than 25 μj, preferably not less than 4 μj and not more than 15 μj, more preferably not less than 4 μj and not more than 10 μj, and may be in other intermediate ranges or values.

Preferably, the energy of the plurality of laser spots decreases in sequence.

The decrease amount of two adjacent laser spots in the plurality of laser spots is 0 to 10 mu j, more preferably 0 to 5 mu j, or other intermediate range or value.

Wherein the spacing 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, more preferably 3-5 μm, and can be other intermediate ranges or values.

Three laser spots are described below as examples. Wherein, the size of three laser spots is equal, the diameter is 30 mu m, the energy of three laser spots is 10 mu j, 8 mu j and 4 mu j respectively, and the interval between two adjacent laser spots is 3 mu m.

Under the premise of achieving the same surface ablation effect, the single laser energy is reduced, laser processing is carried out for many times at the same position, damage to the silicon substrate can be effectively reduced, and then the conversion efficiency is improved.

The comparison data of the single laser processing effect of the present embodiment and the existing single laser spot are shown in table 2:

type(s)	Eta/％	Voc/mV	Jsc/mA/cm ²	FF/％
					Existing single laser spot ablation	22.396	684.3	41.81	78.28
Multi-laser spot ablation	22.419	684.4	41.83	78.31

TABLE 2

Wherein the spot size of the existing single laser is 30 mu m, and the single pulse energy is 18 mu j; the multi-laser spot size was 30 μm with energies of 10 μj, 8 μj, and 4 μj, respectively.

According to the invention, the single laser spot energy is reduced, and the laser multi-beam mode is utilized for processing, so that the thermal damage of laser to the silicon substrate can be reduced to the greatest extent. The electrical performance contrast test shows that: according to the multi-laser ablation technology, the conversion efficiency of the solar cell reaches 22.419%, and compared with the traditional single-laser-spot laser ablation solar cell, the efficiency is improved by 0.023%; the main expression is Voc, jsc, FF with small amplitude improvement, which shows that the repeated low-energy ablation mode has obvious improvement effect on laser thermal injury.

It will be apparent that the embodiments described above are merely some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.

It should be noted that the terms "first," "second," and the like in the description and claims of the present application and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that embodiments of the present application described herein may be implemented in sequences other than those illustrated or described herein.

The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The multi-laser-spot processing method for the solar cell is characterized by comprising the following steps of:

after being split and focused, laser beams emitted by a laser generating system (10) form a plurality of laser spots which are arranged along a straight line on a substrate (60) to be processed, wherein the energy of the plurality of laser spots is the same, part of the energy of the plurality of laser spots is the same or all of the energy of the plurality of laser spots are different;

and the laser spots are scanned and processed according to the set speed and the 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 sequentially reach the same processing position.

2. The method of claim 1, wherein the laser spots are the same or different in size.

3. The method for processing multiple laser spots of a solar cell according to claim 1, wherein the laser beam emitted by the laser generating system (10) is split and focused to obtain a plurality of laser spots:

the shape of the plurality of laser spots comprises one of a circle, a rectangle and a square; a plurality of said laser spots having a size in the range of 6 μm to 500 μm; the distance between two adjacent laser spots in the plurality of laser spots is in the range of 0-10 μm; the number of the plurality of laser spots is 2 to 6.

4. The method of claim 1, wherein the energy of the plurality of laser spots is increased or decreased when the energy of the plurality of laser spots is all different.

5. The method of any one of claims 1 to 4, wherein the method of solar cell multi-laser spot processing comprises modifying a solar cell, wherein the energy of a plurality of laser spots is the same or increasing, and the size of a plurality of laser spots is the same or decreasing.

6. The method of any one of claims 1 to 4, wherein the method of processing multiple laser spots of the solar cell comprises ablating a solar cell film layer, wherein the energy of multiple laser spots is the same or decreasing, and the size of multiple laser spots is the same.

7. The method for processing multiple laser spots of a solar cell according to claim 5, wherein the method for processing multiple laser spots of a solar cell comprises performing laser selective doping treatment on a cell sheet, comprising:

the energy of the plurality of laser spots is larger than or equal to 20 mu j and smaller than or equal to 100 mu j, and the energy of the plurality of laser spots is the same or sequentially increases;

when the energy of the laser spots is sequentially increased, the energy increment of two adjacent laser spots in the laser spots is 0-50 mu j;

the shape of the laser spot is square, and the size of the laser spot is more than or equal to 50 mu m and less than or equal to 300 mu m;

the spacing between adjacent two of the plurality of laser spots is in the range of 0 μm to 10 μm.

8. The method for processing multiple laser spots of the solar cell according to claim 6, wherein the method for processing the multiple laser spots of the solar cell comprises a PERC cell laser back passivation ablation process, comprising:

the energy of the plurality of laser spots is larger than or equal to 4 mu j and smaller than or equal to 25 mu j, and the energy of the plurality of laser spots is the same or gradually decreases;

when the energy of the laser spots is gradually decreased, the energy decrease of two adjacent laser spots in the laser spots is 0-7 mu j;

the shape of the laser spot is circular, and the diameter of the laser spot is more than or equal to 20 mu m and less than or equal to 50 mu m;

9. A multi-laser spot processing device for a solar cell, wherein the multi-laser spot processing device for a solar cell is used for implementing the multi-laser spot processing method for a solar cell according to any one of claims 1 to 8, and the multi-laser spot processing device for a solar cell sequentially comprises a laser generating 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 beams emitted by the laser generating system (10) and splits the laser beams into a plurality of beams, and the energy among the plurality of beams is all the same, part of the same or all different;

the scanning focusing system (40) is used for receiving a plurality of laser beams of the beam splitting system (30), forming a plurality of laser spots which are arranged along a straight line on a substrate (60) to be processed, enabling the energy among the laser spots to be the same, partially the same or completely different, and enabling the laser spots to be scanned and processed according to a set speed and a scanning direction, wherein the scanning direction is consistent with the arrangement direction of the laser spots, and enabling the laser spots to sequentially reach the same processing position.

10. The device according to claim 9, wherein the laser generating system (10) uses a laser having a laser wavelength of 355nm or more and 1064nm or less and a power of 10W or more and 1000W or less.

11. The device of claim 9, wherein the beam splitting system (30) is a diffractive optic.

12. The device of claim 9, wherein the scanning focusing system (40) is a galvanometer and a field lens.