Method and equipment for preparing selective emitter of solar cell

Abstract

The present application discloses a method and equipment for preparing a selective emitter of a solar cell. The method comprises: using a first laser to preheat a preset area of ​​a semi-finished silicon wafer; using a second laser to locally heavily dope the diffusion layer of the semi-finished silicon wafer to form a heavily doped area, wherein the heavily doped area is located within the preset area, and the preset area is not smaller than the heavily doped area; the first laser and the second laser are coaxial. The method and equipment for preparing a selective emitter of a solar cell of the present application embodiment, respectively preheat the preset area of ​​the semi-finished silicon wafer by using a coaxial first laser and a second laser, and locally heavily dope the diffusion layer of the semi-finished silicon wafer to form a heavily doped area, can reduce the damage of the laser to the surface of the silicon wafer during the production process of the laser processing selective emitter solar cell, thereby improving the photoelectric conversion efficiency of the battery.

Description

Technical Field

[0001] The present application relates to the field of laser processing technology, and in particular to a method and equipment for preparing a selective emitter of a solar cell. Background Art

[0002] After the silicon wafer is textured and diffused, the selective emitter solar cell is locally heavily doped in the electrode (printed grid line) area, which can reduce the contact resistance between the electrode and the silicon wafer and improve the photoelectric conversion efficiency of the battery. The existing method for preparing selective emitter solar cells usually uses slurry printing, and then adopts high-temperature diffusion, mask etching and other methods for preparation. Application CN101950780A discloses a method for making selective emitter cells by screen printing. This method involves two screen printings and one mask diffusion. The low production capacity is not conducive to large-scale production. Application CN101820023A discloses a method for preparing a selective emitter of a crystalline silicon solar cell. This method requires local heavy doping in a vacuum, and the process steps are complicated and the cost is extremely high. Application CN102709387A discloses a selective emitter etching process. This method uses a mask to achieve local heavy doping. The process is complicated, and it is difficult to ensure the alignment accuracy of the subsequent process. Application CN102110743A discloses a method for locally laser melting phosphosilicate glass to produce selective emitter solar cells. This method uses laser scanning on the phosphosilicate glass on the surface of a silicon wafer to achieve local heavy doping. The laser has the problem of uneven doping, and higher laser energy can also damage the silicon wafer. Summary of the invention

[0003] The purpose of this application is to solve one of the above-mentioned technical problems at least to a certain extent.

[0004] To this end, the first purpose of the present application is to propose a method for preparing a selective emitter of a solar cell, which can reduce the damage of the laser to the surface of the silicon wafer during the production process of the laser-processed selective emitter solar cell, thereby improving the photoelectric conversion efficiency of the cell.

[0005] The second objective of the present application is to provide a device for preparing a selective emitter of a solar cell.

[0006] In order to achieve the above-mentioned objectives, the first aspect of the present application proposes a method for preparing a selective emitter of a solar cell, comprising: using a first laser to preheat a preset area of ​​a semi-finished silicon wafer; using a second laser to locally heavily dope a diffusion layer of the semi-finished silicon wafer to form a heavily doped area, wherein the heavily doped area is located within the preset area, and the preset area is not smaller than the heavily doped area; the first laser and the second laser are coaxial.

[0007] Optionally, the surface of the diffusion layer is covered with phosphosilicate glass or borosilicate glass, and a first laser is used to preheat a preset area of ​​the semi-finished silicon wafer, including: a galvanometer is provided on the optical path of the first laser and the second laser, and the galvanometer is controlled to deflect so that the first laser scans the entire preset area; or a moving device is used to control the semi-finished silicon wafer or the laser generating device to move in a preset direction so that the first laser scans the entire preset area;

[0008] The diffusion layer of the semi-finished silicon wafer is locally heavily doped using a second laser, including: controlling the deflection of the galvanometer to enable the second laser to scan the entire heavily doped area; or using the moving device to control the semi-finished silicon wafer or the laser generating device to move in a preset direction to enable the second laser to scan the entire heavily doped area.

[0009] Optionally, the scanning trajectories of the first laser and the second laser overlap, and a second time when the second laser arrives at the same position in the scanning trajectory is not earlier than a first time when the first laser arrives at the same position in the scanning trajectory.

[0010] Optionally, when the second time is later than the first time, the time difference between the second time and the first time is less than or equal to 1 ms.

[0011] Optionally, the wavelength of the first laser is 355-1500 nm, and the wavelength of the second laser is 515-1500 nm.

[0012] Optionally, the preset region is a strip-shaped region arranged corresponding to the heavily doped region, and a first width of the preset region is not less than a second width of the heavily doped region.

[0013] Optionally, the first width is 1.2-3 times the second width.

[0014] Optionally, the first laser is a pulse laser or a continuous laser, and the second laser is a pulse laser.

[0015] Optionally, when the first laser is a continuous laser, the power density range of the first laser is 1-15*10 4 W / cm 2 When the first laser is a pulsed laser, the energy density of the first laser is in the range of 0.2-1 J / cm 2 .

[0016] Optionally, the energy density of the second laser is 0.3-2.0 J / cm 2 .

[0017] Optionally, the light spots of the first laser and the second laser are flat-top spots.

[0018] Optionally, the size of the first laser spot is equal to the first width, and the size of the second laser spot is equal to the second width.

[0019] The method for preparing the selective emitter of a solar cell in the embodiment of the present application uses a coaxial first laser and a second laser to preheat a preset area of ​​a semi-finished silicon wafer, and locally heavily dopes the diffusion layer of the semi-finished silicon wafer to form a heavily doped area. This can reduce the damage to the surface of the silicon wafer caused by the laser during the production of the laser-processed selective emitter solar cell, thereby improving the photoelectric conversion efficiency of the battery.

[0020] In order to achieve the above-mentioned purpose, the second embodiment of the present application proposes a device for preparing a selective emitter of a solar cell, comprising: a laser generating device, a scanning focusing component and a workbench,

[0021] The laser generating device is used to generate a first laser for preheating a preset area of ​​a semi-finished silicon wafer, and to generate a second laser for locally heavily doping a diffusion layer of the semi-finished silicon wafer, wherein the first laser and the second laser are coaxial; the scanning focusing component is used to control the first laser and the second laser to focus on the semi-finished silicon wafer, so that the first laser preheats the preset area, and the second laser locally heavily dopes the diffusion layer of the semi-finished silicon wafer; the workbench is used to place the semi-finished silicon wafer.

[0022] Optionally, the laser generating device includes a first laser source, and the first laser source is used to generate the first laser and the second laser; or

[0023] The laser generating device comprises a first laser source and a second laser source, wherein the first laser source is used to generate the first laser, and the second laser source is used to generate the second laser.

[0024] Optionally, when the laser generating device includes the first laser source and the second laser source, the first laser and the second laser are converged to be coaxial through a beam combining component.

[0025] Optionally, the scanning and focusing components are a galvanometer and a field lens, and the galvanometer and the field lens are arranged on the optical paths of the first laser and the second laser. The field lens is an achromatic field lens, which is used for focusing and eliminating the chromatic aberration of the first laser and the second laser; the galvanometer is a multi-wavelength galvanometer, which is used for controlling the first laser and the second laser to scan the entire preset area in sequence.

[0026] Optionally, the scanning and focusing component is a moving device and a focusing mirror, the focusing mirror is used to focus the first laser and the second laser; the moving device is used to control the semi-finished silicon wafer or the laser generating device to move along a preset direction, so that the first laser and the second laser scan the entire preset area in turn.

[0027] Optionally, the device further includes a timing controller, which is connected to the laser generating device and is used to control the time difference between the emission of the first laser and the emission of the second laser.

[0028] Optionally, the device further comprises an optical shaping device, and the optical shaping device is used to shape the spot shape of the first laser and / or the second laser into a flat-top spot.

[0029] Optionally, the device further includes an industrial computer, which is connected to the timing controller and is used to control the timing controller.

[0030] The equipment for preparing the selective emitter of a solar cell in the embodiment of the present application uses a coaxial first laser and a second laser to preheat a preset area of ​​a semi-finished silicon wafer, and locally heavily dopes the diffusion layer of the semi-finished silicon wafer to form a heavily doped area. This can reduce the damage to the surface of the silicon wafer caused by the laser during the production of the laser-processed selective emitter solar cell, thereby improving the photoelectric conversion efficiency of the battery.

[0031] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0033] Figure 1 is a flow chart of a method for preparing a selective emitter of a solar cell according to an embodiment of the present application;

[0034] Figure 2 It is a schematic structural diagram of a device for preparing a selective emitter of a solar cell according to an embodiment of the present application;

[0035] Figure 3 is a schematic structural diagram of a device for preparing a selective emitter of a solar cell according to another embodiment of the present application;

[0036] Figure 4 It is a structural schematic diagram of a device for preparing a selective emitter of a solar cell according to another embodiment of the present application;

[0037] Figure 5 is a schematic structural diagram of a device for preparing a selective emitter of a solar cell according to another embodiment of the present application;

[0038] Figure 6 It is a structural schematic diagram of a device for preparing a selective emitter of a solar cell according to a specific embodiment of the present application;

[0039] Figure 7 is a schematic structural diagram of a device for preparing a selective emitter of a solar cell according to another specific embodiment of the present application;

[0040] Figure 8 is a schematic structural diagram of a device for preparing a selective emitter of a solar cell according to another specific embodiment of the present application;

[0041] Fig. 9 It is a schematic structural diagram of a device for preparing a selective emitter of a solar cell according to an embodiment of the present application;

[0042] Fig.10 is a schematic diagram of a laser light path of another specific embodiment of the present application;

[0043] Fig.11 It is a schematic structural diagram of a device for preparing a selective emitter of a solar cell according to another specific embodiment of the present application. DETAILED DESCRIPTION

[0044] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0045] The present invention is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed by the present invention.

[0046] The following describes a method and equipment for preparing a selective emitter for a solar cell according to an embodiment of the present application with reference to the accompanying drawings.

[0047] The preparation principle is as follows: When processing solar cells, a layer of phosphosilicate glass or borosilicate glass will be formed on the surface of the silicon wafer after texturing and diffusion. The phosphorus atoms in the phosphosilicate glass or the boron atoms in the borosilicate glass are used as diffusion sources. The phosphorus atoms or boron atoms are activated through preheating treatment, and then lasers are used to propel them so that they diffuse to a certain depth in the silicon wafer to form a PN junction, thereby achieving local heavy doping. Since the pulse energy required for doping is low and the laser repetition frequency used is high, the processing speed can be increased and the production capacity of the equipment can be improved. On the other hand, lower laser energy can reduce the damage to the surface of the silicon wafer by laser processing and improve the photoelectric conversion efficiency of the battery.

[0048] Figure 1 It is a flow chart of a method for preparing a selective emitter of a solar cell according to an embodiment of the present application.

[0049] like Figure 1 As shown, the method for preparing a selective emitter of a solar cell comprises:

[0050] S1, using a first laser to preheat a preset area of ​​a semi-finished silicon wafer.

[0051] Among them, the semi-finished silicon wafer refers to a silicon wafer that has been textured (or not textured) and diffused to form a diffusion layer, and a layer of phosphosilicate glass or borosilicate glass is formed on its surface.

[0052] By preheating the semi-finished silicon wafer with the first laser, the phosphorus atoms in the phosphorus silicon glass or the boron atoms in the borosilicate glass on the diffusion layer can obtain a certain initial thermal motion speed, which is beneficial to the subsequent steps to advance the phosphorus atoms or boron atoms.

[0053] Specifically, there are three preheating treatment methods:

[0054] First way:

[0055] A galvanometer is arranged on the optical path of the first laser and the second laser.

[0056] The galvanometer deflection is controlled to change the optical path of the first laser irradiation, thereby realizing scanning of the entire preset area.

[0057] Second way:

[0058] The moving device is used to control the semi-finished silicon wafer to move along a preset direction, while the irradiation position of the first laser remains unchanged, so that the first laser scans the entire preset area.

[0059] The third way:

[0060] The moving device is used to control the entire laser generating device to move along a preset direction, while the position of the semi-finished silicon wafer remains unchanged, thereby enabling the first laser to scan the entire preset area.

[0061] S2, using a second laser to locally heavily dope the diffusion layer of the semi-finished silicon wafer to form a heavily doped area.

[0062] Specifically, the diffusion layer of the semi-finished silicon wafer can be irradiated with the second laser to perform local heavy doping to form a heavily doped area. The heavy doping treatment can be performed simultaneously with the preheating treatment or after the preheating treatment, so that the phosphorus atoms in the phosphorus silicon glass or the boron atoms in the borosilicate glass on the diffusion layer maintain a certain initial thermal motion speed.

[0063] The first laser and the second laser are coaxial, that is, the trajectories of the first laser and the second laser on the semi-finished silicon wafer are the same.

[0064] The surface of the diffusion layer of the semi-finished silicon wafer is covered with phosphosilicate glass or borosilicate glass. The diffusion layer can be irradiated with a second laser. Since phosphorus atoms or boron atoms have a certain initial thermal motion speed, laser propulsion is performed in this step so that the phosphorus atoms in the phosphosilicate glass or the boron atoms in the borosilicate glass replace the silicon atoms in the diffusion layer to form a heavily doped area.

[0065] Specifically, there are also three ways of local heavy doping:

[0066] First way:

[0067] The galvanometer deflection is controlled to change the optical path of the second laser irradiation, thereby realizing scanning of the entire heavily doped area.

[0068] Second way:

[0069] The moving device is used to control the semi-finished silicon wafer to move along a preset direction, while the irradiation position of the second laser remains unchanged, so that the second laser scans the entire heavily doped area.

[0070] The third way:

[0071] The moving device is used to control the entire laser generating device to move along a preset direction, while the position of the semi-finished silicon wafer remains unchanged, thereby enabling the second laser to scan the entire heavily doped area.

[0072] In this embodiment, the scanning trajectories of the first laser and the second laser overlap, and the second time when the second laser reaches the same position in the scanning trajectory is not earlier than the first time when the first laser reaches the same position in the scanning trajectory. When the second time is later than the first time, the time difference between the second time and the first time is less than or equal to 1ms. Preferably, the time difference is 10ps to 1ms.

[0073] The wavelength of the first laser is 355 to 1500 nm, and the wavelength of the second laser is 515 to 1500 nm.

[0074] In one embodiment of the present application, the preset region may be a strip region corresponding to the heavily doped region, and the first width of the preset region is not less than the second width of the heavily doped region, so as to achieve the purpose of energy saving. Preferably, the first width is 1.2-3 times the second width.

[0075] The light spots of the first laser and the second laser are flat-top light spots. The size of the light spot of the first laser is equal to the first width, and the size of the second light spot is equal to the second width.

[0076] It should be understood that the first laser may be a pulse laser or a continuous laser, and the second laser is preferably a pulse laser.

[0077] When the first laser is a continuous laser, the power density range of the first laser is 1-15*10 4 W / cm 2 When the first laser is a pulsed laser, the energy density of the first laser is in the range of 0.2-1 J / cm 2 The energy density of the second laser is 0.3-2.0 J / cm 2 Compared with the prior art, the energy density of the second laser is reduced by about 30%.

[0078] The method for preparing the selective emitter of a solar cell in the embodiment of the present application uses a coaxial first laser and a second laser to preheat a preset area of ​​a semi-finished silicon wafer, and locally heavily dopes the diffusion layer of the semi-finished silicon wafer to form a heavily doped area. This can reduce the damage to the surface of the silicon wafer caused by the laser during the production of the laser-processed selective emitter solar cell, thereby improving the photoelectric conversion efficiency of the battery.

[0079] Several specific embodiments are described in detail below.

[0080] Embodiment 1:

[0081] A method for preparing a selective emitter for a solar cell.

[0082] The first laser and the coaxially arranged second laser are sequentially irradiated on the preset area of ​​the semi-finished silicon wafer. The first laser and the second laser are respectively scanned in the entire preset area and the heavily doped area through the galvanometer. In this process, laser pretreatment is completed so that the phosphorus atoms in the phosphorus silicon glass or the boron atoms in the borosilicate glass obtain a certain initial thermal motion speed. Laser heavy doping is also completed so that the phosphorus atoms or boron atoms activated by pretreatment enter the surface layer of the semi-finished silicon wafer. After solidification, the phosphorus atoms or boron atoms replace the silicon atoms to form a heavily doped area. Among them, the scanning trajectories of the first laser and the second laser are the same, and the time difference is ≤1ms, preferably 10ps~1ms, so that the best doping effect can be achieved with the lowest power combination.

[0083] In this embodiment, the width of the preset area is not less than the width of the heavily doped area, the width of the first laser spot is equal to the width of the preset area, and the width of the second laser spot is equal to the width of the heavily doped area. The second laser spot is preferably a flat-top spot, which has good spot uniformity and more uniform doping.

[0084] The wavelength of the first laser is 355 to 1500 nm, preferably 1030 to 1080 nm. The power density range of the first laser when it is a continuous laser is 1-15*10 4 W / cm 2When the first laser is a pulsed laser, the energy density range is 0.3-1J / cm 2 , preferably 0.7 to 1.5 J / cm 2 The wavelength of the second laser is 515 to 1500 nm, preferably 515 to 545 nm. The energy density of the second laser is 0.5 to 2.0 J / cm 2 , preferably 0.7 to 1.5 J / cm 2 .

[0085] The laser scanning speed can be selected according to actual needs.

[0086] The following experimental data prove that the preparation method of this embodiment is superior to the prior art.

[0087] The semi-finished silicon wafer is doped to reduce the original square resistance of 120Ω / □ to 80Ω / □.

[0088] 1) In the prior art, without laser pretreatment, only a pulsed laser with a wavelength of 515 nm is used, the second laser spot size is 120 μm, and the required pulse energy density is 0.9 J / cm 2 .

[0089] Using the preparation method of this embodiment, the first laser is a 1064nm continuous wave infrared laser, and the second laser is a pulsed laser with a wavelength of 515nm. The spot size of both is 120μm. The two are scanned coaxially, and the first laser leads the second laser by 5μs to reach the semi-finished silicon wafer.

[0090] The first laser power is set to 10W. To achieve the same processing effect, the required second laser pulse energy is reduced to 0.7J / cm 2 ; Set the first laser power to 15W, and the required second laser pulse energy density is reduced to 0.66J / cm 2 .

[0091] 2) In the prior art, without laser pretreatment, only a pulsed laser with a wavelength of 532nm is used, the second laser spot size is 120μm, and the required pulse energy density is 0.9J / cm 2 .

[0092] Using the preparation method of this embodiment, the first laser is a 1064nm continuous wave infrared laser, and the second laser is a pulsed laser with a wavelength of 532nm. The spot size of both lasers is 120μm. The two lasers are coaxially scanned, and the first laser reaches the silicon wafer 5μs ahead of the second laser.

[0093] The first laser power is set to 10W. To achieve the same processing effect, the required second laser pulse energy is reduced to 0.7J / cm 2; Set the first laser power to 15W, and the required second laser pulse energy density is reduced to 0.66J / cm 2 .

[0094] 3) In the prior art, without laser pretreatment, only a pulsed laser with a wavelength of 1064nm is used, the second laser spot size is 120μm, and the required pulse energy density is 1.2J / cm 2 .

[0095] Using the preparation method of this embodiment, the first laser is a 1064nm continuous wave infrared laser, and the second laser is a pulsed laser with a wavelength of 1064nm. The spot size of both lasers is 120μm. The two lasers are coaxially scanned, and the first laser reaches the silicon wafer 5μs ahead of the second laser.

[0096] The first laser power is set to 10W. To achieve the same processing effect, the required second laser pulse energy is reduced to 1J / cm 2 ; Set the first laser power to 15W, and the required second laser pulse energy density is reduced to 0.9J / cm 2 .

[0097] It can be seen that to achieve the same doping effect, the required first laser pulse energy density is greatly reduced, which significantly reduces the damage of the pulse laser to the silicon wafer surface; at the same time, due to the reduced pulse energy density, the first laser can work at a higher repetition frequency, and the equipment production efficiency is also improved. The solar cell prepared by the method of this embodiment has a cell efficiency that is 0.02 to 0.05% higher than that of the simple second laser processing.

[0098] The preparation equipment corresponding to the above method includes a laser source, a field lens, a scanning device and a workbench.

[0099] The laser source generates a first laser for pre-processing a preset area of ​​the semi-finished silicon wafer, and a second laser for irradiating a diffusion layer of the semi-finished silicon wafer to achieve heavy doping.

[0100] The field lens is used to focus the first laser and the second laser to form a light spot on the semi-finished silicon wafer.

[0101] The scanning device is used to make the first laser scan through the entire preset area and the second laser scan through the heavily doped area. The scanning device is a galvanometer mirror arranged in front of the field mirror.

[0102] A workbench is used to place semi-finished silicon wafers.

[0103] In this embodiment, the laser source includes a first laser source and a second laser source, which are combined by a beam combining device to form a coaxial first laser and a second laser.

[0104] The beam combining device may be a beam combining mirror or other device in the prior art.

[0105] When the laser source is two separately arranged first laser sources and second laser sources, a timing controller connected to both of them is also included.

[0106] The timing controller is used to give a signal to control the emission timing of the first laser and the second laser, so that the second laser and the first laser reach the semi-finished silicon wafer at the same time, or reach the semi-finished silicon wafer with a certain time difference. The scanning tracks of the two are the same.

[0107] Embodiment 2:

[0108] The method in this embodiment differs from that in Embodiment 1 only in the scanning method.

[0109] By controlling the first laser and the second laser to move relative to the semi-finished silicon wafer, the first laser scans through the entire preset area and the second laser scans through the heavily doped area. The moving direction and speed can be controlled according to actual processing requirements, such as moving in a straight line or in a plane in a certain direction.

[0110] The preparation equipment corresponding to the above method is different from that in Example 1 only in the scanning device.

[0111] In this embodiment, the scanning device is a linear motion device or a two-dimensional motion module that drives the workbench to move linearly or in a plane. The scanning device drives the workbench and the semi-finished silicon wafer to move together, and completes the scanning through the irradiation positions of the first laser and the second laser.

[0112] The scanning device can also be a linear motion device or a two-dimensional motion module that drives the laser source and related components to move linearly or in a plane, so as to move the first laser and the second laser to complete the scanning through the entire preset area and the heavily doped area.

[0113] In order to implement the above-mentioned embodiment, the present application also proposes a device for preparing a selective emitter of a solar cell.

[0114] like Figure 2 As shown, the equipment for preparing the selective emitter of a solar cell includes a laser generating device 100 , a scanning and focusing component 200 and a working table 300 .

[0115] The laser generating device 100 is used to generate a first laser for preheating a preset area of ​​a semi-finished silicon wafer, and to generate a second laser for locally heavily doping a diffusion layer of the semi-finished silicon wafer. The first laser and the second laser are coaxial.

[0116] The laser generating device 100 may be a first laser source 110, and the first laser source 110 may generate a first laser and a second laser. Figure 3 As shown, the laser generating device 100 may also be composed of a first laser source 110 and a second laser source 120. The first laser source 110 is used to generate a first laser, and the second laser source 120 is used to generate a second laser. When the laser generating device 100 includes the first laser source 110 and the second laser source 120, as shown in FIG. Figure 3 As shown, the first laser and the second laser can be converged into a coaxial line through the beam combining component 130 .

[0117] The scanning focusing component 200 is used to control the first laser and the second laser to focus on the semi-finished silicon wafer, so that the first laser performs preheating treatment on a preset area, and the second laser performs local heavy doping on the diffusion layer of the semi-finished silicon wafer.

[0118] In one embodiment of the present application, Figure 4 As shown, the scanning and focusing component 200 includes a galvanometer mirror 210 and a field lens 220 .

[0119] The galvanometer mirror 210 and the field lens 220 are disposed on the optical paths of the first laser beam and the second laser beam.

[0120] The galvanometer 210 is a multi-wavelength galvanometer, which is used to control the first laser and the second laser to scan the entire preset area and the heavily doped area in sequence.

[0121] The field lens 220 is an achromatic field lens, which is used to focus the first laser and the second laser and to eliminate the chromatic aberration between the first laser and the second laser.

[0122] In another embodiment of the present application, the scanning focusing component 200 includes a focusing mirror 230 and a moving device 240 .

[0123] The focusing mirror 230 is used to focus the first laser and the second laser, and is preferably an achromatic focusing mirror to eliminate the chromatic aberration between the first laser and the second laser.

[0124] The moving device 240 is used to control the semi-finished silicon wafer or the laser generating device 100 to move along a preset direction so that the first laser and the second laser scan the entire preset area and the heavily doped area in sequence. Figure 5 As shown, when the moving device 240 controls the movement of the semi-finished silicon wafer (when the semi-finished silicon wafer is fixed on the workbench 300, the workbench 300 can be moved to drive the semi-finished silicon wafer to move), the position of the laser generating device 100 remains unchanged to achieve scanning; Figure 6 As shown, when the entire laser generating device 100 is controlled to move, the position of the semi-finished silicon wafer remains unchanged to achieve scanning.

[0125] The workbench 300 is used to place semi-finished silicon wafers.

[0126] In one embodiment of the present application, Figure 7As shown, the manufacturing equipment for the selective emitter of a solar cell further includes a timing controller 400 .

[0127] The timing controller 400 is connected to the laser generating device 100 and is used to send a signal to control the time difference between the emission of the first laser and the emission of the second laser.

[0128] In another embodiment of the present application, Figure 8 As shown, the equipment for preparing the selective emitter of a solar cell further includes an optical shaping device 500 .

[0129] The optical shaping device is used to shape the spot shape of the second laser (and) the first laser into a flat-top spot, preferably into a rectangular or square spot.

[0130] The optical shaping device may be disposed at a position which is not limited to the optical path downstream of the first laser source 110 , the optical path downstream of the second laser source 120 , or the optical path before the first laser and the second laser are converged by the beam combining component 130 .

[0131] In another embodiment of the present application, Fig. 9 As shown, the equipment for preparing the selective emitter of a solar cell further includes an industrial computer 600 .

[0132] The industrial computer 600 is connected to the timing controller 400 and is used to control the timing controller 400, that is, to control the time difference between the first laser and the second laser.

[0133] Furthermore, the industrial computer 600 can also be connected to a laser generating device, a scanning focusing device, etc., to control the scanning path, laser switch, etc.

[0134] In one embodiment of the present application, the equipment for preparing the selective emitter of a solar cell further includes a reflector, an optical gate, a beam expander, etc. arranged on the optical path of the first laser and / or the second laser.

[0135] Specific examples include Fig.10 and Fig.11 As shown. The infrared laser (first laser source) 110 generates infrared light, which passes through the optical gate 111 and the beam expander 112 in sequence, irradiates the transmitting mirror 113, passes through the long-wavelength dichroic mirror 114, irradiates the dual-wavelength reflector 115, and finally irradiates the dual-wavelength galvanometer 210 and the achromatic field mirror 220. The green laser (second laser source) 120 generates green light, which passes through another optical gate 111, another beam expander 112 and the shaping lens 500 in sequence, then irradiates the long-wavelength dichroic mirror 114, is reflected on the dual-wavelength reflector 115, and finally irradiates the dual-wavelength galvanometer 210 and the achromatic field mirror 220.

[0136] The timing controller 400 can send control signals to control the infrared laser and the green laser respectively. The industrial computer 600 can send a galvanometer motion signal to the dual-wavelength galvanometer 210 to control its movement. The industrial computer 600 can also send a laser trigger signal to the timing controller 400 to control the timing controller 400.

[0137] The equipment for preparing the selective emitter of a solar cell in the embodiment of the present application uses a coaxial first laser and a second laser to preheat a preset area of ​​a semi-finished silicon wafer, and locally heavily dopes the diffusion layer of the semi-finished silicon wafer to form a heavily doped area. This can reduce the damage to the surface of the silicon wafer caused by the laser during the production of the laser-processed selective emitter solar cell, thereby improving the photoelectric conversion efficiency of the battery.

[0138] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0139] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute the instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or otherwise processing in a suitable manner if necessary, and then stored in a computer memory.

[0140] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0141] It should be noted that, in the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

Claims

1. A method for preparing a selective emitter of a solar cell, characterized in that: include: Using a first laser to preheat a preset area of ​​a semi-finished silicon wafer, the surface of a diffusion layer of which is covered by phosphosilicate glass or borosilicate glass; Using a second laser to locally heavily dope the diffusion layer of the semi-finished silicon wafer to form a heavily doped region, wherein the heavily doped region is located in the preset region and the preset region is not smaller than the heavily doped region; The first laser and the second laser are coaxial; The scanning trajectories of the first laser and the second laser overlap, and a second time when the second laser reaches the same position in the scanning trajectory is not earlier than a first time when the first laser reaches the same position in the scanning trajectory; When the second time is later than the first time, the time difference between the second time and the first time is less than or equal to 1 ms; The wavelength of the first laser is 1030-1080 nm, and the wavelength of the second laser is 515-545 nm.

2. The method according to claim 1, characterized in that The first laser is used to preheat the preset area of ​​the semi-finished silicon wafer, including: A galvanometer is provided on the optical path of the first laser and the second laser, and the galvanometer is controlled to deflect so that the first laser scans the entire preset area; or Using a moving device to control the semi-finished silicon wafer or the laser generating device to move along a preset direction, so that the first laser scans the entire preset area; The diffusion layer of the semi-finished silicon wafer is locally heavily doped using a second laser, comprising: controlling the galvanometer to deflect so that the second laser scans the entire heavily doped region; or The moving device is used to control the semi-finished silicon wafer or the laser generating device to move along a preset direction, so that the second laser scans the entire heavily doped area.

3. The method according to claim 1, characterized in that The preset region is a strip-shaped region arranged corresponding to the heavily doped region, and a first width of the preset region is not less than a second width of the heavily doped region.

4. The method according to claim 3, characterized in that The first width is 1.2-3 times the second width.

5. The method according to claim 1, characterized in that The first laser is a pulse laser or a continuous laser, and the second laser is a pulse laser.

6. The method according to claim 5, characterized in that When the first laser is a continuous laser, the power density range of the first laser is 1-15*10 4 W / cm 2 When the first laser is a pulse laser, the pulse density of the first laser is in the range of 0.2-1 J / cm 2 .

7. The method according to claim 5, characterized in that The pulse density of the second laser is 0.3-2.0 J / cm 2 .

8. The method according to claim 1, characterized in that The light spots of the first laser and the second laser are flat-top light spots.

9. The method according to claim 3, characterized in that The size of the light spot of the first laser is equal to the first width, and the size of the light spot of the second laser is equal to the second width.

10. A device for preparing a selective emitter of a solar cell, characterized in that: include: Laser generator, scanning and focusing components and workbench, The laser generating device is used to generate a first laser for preheating a preset area of ​​the semi-finished silicon wafer, and to generate a second laser for locally heavily doping a diffusion layer of the semi-finished silicon wafer, wherein the first laser and the second laser are coaxial, and the surface of the diffusion layer of the semi-finished silicon wafer is covered with phosphosilicate glass or borosilicate glass; The scanning focusing component is used to control the first laser and the second laser to focus on the semi-finished silicon wafer, so that the first laser performs preheating treatment on the preset area, and the second laser performs local heavy doping on the diffusion layer of the semi-finished silicon wafer; The workbench is used to place the semi-finished silicon wafer; The scanning trajectories of the first laser and the second laser overlap, and a second time when the second laser reaches the same position in the scanning trajectory is not earlier than a first time when the first laser reaches the same position in the scanning trajectory; When the second time is later than the first time, the time difference between the second time and the first time is less than or equal to 1 ms; The wavelength of the first laser is 1030-1080 nm, and the wavelength of the second laser is 515-545 nm.

11. The manufacturing device for the selective emitter of a solar cell according to claim 10, characterized in that: The laser generating device comprises a first laser source, and the first laser source is used to generate the first laser and the second laser; or The laser generating device comprises a first laser source and a second laser source, wherein the first laser source is used to generate the first laser, and the second laser source is used to generate the second laser.

12. The manufacturing device for the selective emitter of a solar cell according to claim 11, characterized in that: When the laser generating device includes the first laser source and the second laser source, the first laser and the second laser are converged to be coaxial through a beam combining component.

13. The manufacturing device for the selective emitter of a solar cell according to claim 10, characterized in that: The scanning and focusing components are a galvanometer and a field lens. The galvanometer and the field lens are arranged on the optical paths of the first laser and the second laser, and the field lens is an achromatic field lens for focusing and eliminating the chromatic aberration of the first laser and the second laser; The galvanometer is a multi-wavelength galvanometer, which is used to control the first laser and the second laser to scan the entire preset area in sequence.

14. The manufacturing device for the selective emitter of a solar cell according to claim 10, characterized in that: The scanning and focusing components are a moving device and a focusing mirror. The focusing mirror is used to focus the first laser and the second laser; The moving device is used to control the semi-finished silicon wafer or the laser generating device to move along a preset direction, so that the first laser and the second laser scan the entire preset area in sequence.

15. The manufacturing device for the selective emitter of a solar cell according to claim 10, characterized in that: The device also includes a timing controller, The timing controller is connected to the laser generating device and is used to control the time difference between the emission of the first laser and the emission of the second laser.

16. The manufacturing device for the selective emitter of a solar cell according to claim 10, characterized in that: The device also includes an optical shaping device, The optical shaping device is used to shape the spot shape of the first laser and / or the second laser into a flat-top spot.

17. The manufacturing device for the selective emitter of a solar cell according to claim 15, characterized in that: The equipment also includes an industrial computer, The industrial computer is connected to the timing controller and is used to control the timing controller.

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