WO2023072013A1 - 发射极、选择性发射极电池的制备方法及选择性发射极电池 - Google Patents

发射极、选择性发射极电池的制备方法及选择性发射极电池 Download PDF

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WO2023072013A1
WO2023072013A1 PCT/CN2022/127190 CN2022127190W WO2023072013A1 WO 2023072013 A1 WO2023072013 A1 WO 2023072013A1 CN 2022127190 W CN2022127190 W CN 2022127190W WO 2023072013 A1 WO2023072013 A1 WO 2023072013A1
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layer
emitter
boron
selective emitter
doped
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PCT/CN2022/127190
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French (fr)
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刘成法
陈艺琦
邹杨
刘志远
王尧
陈达明
张学玲
陈奕峰
冯志强
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天合光能股份有限公司
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Priority to AU2022375265A priority Critical patent/AU2022375265A1/en
Priority to EP22885890.8A priority patent/EP4328984A1/en
Priority to JP2023573123A priority patent/JP2024520064A/ja
Publication of WO2023072013A1 publication Critical patent/WO2023072013A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present application belongs to the technical field of solar cells, for example, relates to an emitter, a preparation method of a selective emitter cell and a selective emitter cell.
  • the selective emitter in a solar cell is a structure in which the area where the metal grid lines are in contact with the silicon wafer is heavily doped, and the area where the non-metal contact is in the silicon wafer is lightly doped.
  • This structure can reduce the contact resistance of the metal contact area and reduce the series resistance of the battery.
  • the lightly doped area can effectively reduce the recombination of carriers and improve surface passivation. Therefore, the preparation of the selective emitter structure will improve the fill factor of the battery and the short-wave response of the battery, and ultimately improve the efficiency of the battery.
  • N-type TOPCon cells are considered to be the next generation of Passivated Emitter and Rear Cell (PERC) cell upgrades that can improve solar cell efficiency.
  • the front-side boron-enhanced selective emitter structure is an essential process for TOPCon cells to improve cell efficiency, but there is no mature process that can be mass-produced at low cost in related technologies.
  • two-step diffusion, reverse etching, and pre-deposited patterned boron sources are often used to prepare selective emission electrodes in TOPCon cells, but the economy is not high.
  • the laser doping process in the related art is difficult to dope boron atoms in borosilicate glass into silicon, and the solid solubility of boron atoms in silicon oxide and silicon is different, resulting in a sharp drop in the surface concentration after laser treatment. While the junction depth can be increased, a good ohmic contact cannot be formed.
  • CN109742172A discloses a method for making N-type selective emitter double-sided battery by laser doping with spin-coated boron source.
  • the preparation method includes: making N-type silicon chip texture, using spin-coating method to spin-coat organic boron source on the front surface, drying, and diffusion furnace Medium diffusion to form front lightly doped emitter, front borosilicate glass (BSG) laser doping to form heavily doped selective emitter, back cleaning to remove silica glass (PSG), rear phosphorus diffusion to form phosphorus back field, front and back Deposit anti-reflective passivation film, print front and back metal electrodes to complete battery production.
  • BSG borosilicate glass
  • PSG silica glass
  • rear phosphorus diffusion to form phosphorus back field
  • front and back Deposit anti-reflective passivation film print front and back metal electrodes to complete battery production.
  • CN112670353A discloses a boron-doped selective emitter battery and its preparation method.
  • the selective emitter battery includes N-type crystalline silicon, two positive electrodes arranged on the front side of the N-type crystalline silicon and the Two negative electrodes on the back of the N-type crystalline silicon, the back of the N-type crystalline silicon is provided with a SiO 2 layer, and a P-doped polysilicon layer is provided on the SiO 2 layer.
  • it discloses the preparation of selective boron SE structures by means of boron paste printing + laser propulsion.
  • CN113035976A discloses a boron-doped selective emitter and its preparation method, and a boron-doped selective emitter battery.
  • the preparation method includes: preparing a heavily doped region and a lightly doped region on the surface of a silicon wafer after texturing; The surface is covered with a layer of boron dopant, and the coverage area of the boron dopant is not smaller than the area size of the heavily doped region; then laser doping is performed on the boron dopant located in the heavily doped region to form silicon boride; then boron Carry out high-temperature advancement of SiC to form a heavily doped region; then form a lightly doped region on the surface of the silicon wafer to obtain a boron-doped selective emitter.
  • This application provides emitter, selective emitter cell preparation method and selective emitter cell, using at least two wavelengths of lasers to do boron doping on the surface of the silicon wafer, which can effectively adjust the boron doping concentration and depth on the surface of the silicon wafer .
  • the present application provides a method for preparing an emitter.
  • the method for preparing an emitter includes: sequentially irradiating the boron-rich layer with at least two lasers of different wavelengths, so as to successively irradiate the boron in the boron-rich layer Atoms are doped to the same area of the silicon wafer that results in the emitter.
  • the present application provides a method for preparing a selective emitter battery, the preparation method comprising: texturizing a silicon wafer, preparing a lightly doped emitter and a boron-rich layer, preparing a heavily doped selective emitter and preparing metal electrodes to obtain the selective emitter battery.
  • the heavily doped selective emitter is prepared according to the preparation method of the emitter described in the first aspect, the first laser doping and the second laser doping successively remove the boron atoms in the boron-rich layer Pattern doping to the same area of the surface of the lightly doped emitter results in the heavily doped selective emitter embedded in the lightly doped emitter.
  • the present application provides a selective emitter battery, which is obtained by using the preparation method of the selective emitter battery described in the second aspect.
  • FIG. 1 is a schematic structural diagram of a selective emitter battery provided in the present application.
  • 1-silicon wafer substrate 2-lightly doped emitter; 3-heavily doped selective emitter; 4-front aluminum oxide layer; 5-front passivation film layer; 6-front metal electrode; 7- Tunneling layer; 8-doped polysilicon layer; 9-back passivation film layer; 10-back metal electrode.
  • This application provides emitter, selective emitter cell preparation method and selective emitter cell, using the characteristics of the boron-rich layer surface has different response to different bands of laser light, and different wavelength lasers have different depths of thermal action on silicon, using at least two
  • the boron doping on the surface of the silicon wafer is carried out by the laser of different wavelengths, which can effectively adjust the concentration and depth of boron doping on the surface of the silicon wafer.
  • two or more wavelengths of lasers are used for patterned laser doping in sequence, which can precisely control the surface concentration and junction depth of the laser region to obtain heavy doping selectivity.
  • emitter thereby increasing the junction depth while increasing the surface concentration of the heavily doped selective emitter.
  • the preparation method of the selective emitter cell provided by the present application is simple and easy to operate, which can reduce the time cost of production, expand the process window, and promote the development of high-efficiency solar cell preparation technology.
  • the present application provides a method for preparing an emitter.
  • the method for preparing an emitter includes: sequentially irradiating the boron-rich layer with at least two lasers of different wavelengths, and sequentially irradiating the boron atoms in the boron-rich layer Doping to the same area of the silicon wafer yields the emitter.
  • the preparation method of the emitter provided by this application utilizes the characteristics that the surface of the boron-rich layer responds differently to lasers of different wavelengths, and the characteristics of the different depths of thermal action of different wavelengths of lasers on silicon, and uses at least two wavelengths of lasers to perform boron doping on the surface of the silicon wafer. Doping can effectively adjust the concentration and depth of boron doping on the surface of the silicon wafer.
  • sequentially irradiating the boron-rich layer with at least two lasers of different wavelengths includes: after irradiating the boron-rich layer with the first laser, irradiating the boron-rich layer with the second laser.
  • the wavelength of the first laser is ⁇ 450nm, such as 440nm, 420nm, 400nm, 380nm, 350nm, 320nm, 300nm, 280nm, 250nm, 220nm, 200nm, 180nm, 150nm or 100nm; Wavelength > 450nm, for example, can be 460nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 850nm, 900nm, 950nm, 1000nm or 1200nm; other unlisted values within this range are also applicable.
  • sequentially irradiating the boron-rich layer with at least two lasers of different wavelengths includes: after irradiating the boron-rich layer with the first laser, irradiating the boron-rich layer with the second laser.
  • the wavelength of the first laser is >450nm, for example, it can be 460nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 850nm, 900nm, 950nm, 1000nm or 1200nm;
  • the wavelength of the second laser is ⁇ 450nm, for example, can be 440nm, 420nm, 400nm, 380nm, 350nm, 320nm, 300nm, 280nm, 250nm, 220nm, 200nm, 180nm, 150nm or 100nm; other unlisted values within this range are also applicable.
  • the present application provides two schemes for preparing the emitter by laser doping: (1) sequentially doping the boron atoms in the boron-rich layer to the same area on the surface of the silicon wafer by using a laser with a wavelength less than 450nm and a laser with a wavelength greater than 450nm; 2) Doping the boron atoms in the boron-rich layer to the same area on the surface of the silicon wafer sequentially by using a laser with a wavelength greater than 450nm and a laser with a wavelength less than 450nm.
  • the present application provides a method for preparing a selective emitter battery, the preparation method comprising: texturizing a silicon wafer, preparing a lightly doped emitter and a boron-rich layer, preparing a heavily doped selective emitter and preparing metal electrodes to obtain the selective emitter battery.
  • the heavily doped selective emitter is prepared according to the preparation method of the emitter described in the first aspect, the first laser doping and the second laser doping successively remove the boron atoms in the boron-rich layer Pattern doping to the same area of the surface of the lightly doped emitter results in the heavily doped selective emitter embedded in the lightly doped emitter.
  • This application provides two schemes for preparing heavily doped selective emitters by laser doping: (1) using lasers with wavelengths less than 450nm and lasers with wavelengths greater than 450nm to sequentially pattern and dope the boron atoms in the boron-rich layer to light Doping the same area on the surface of the emitter; (2) sequentially doping boron atoms in the boron-rich layer to the same area on the surface of the lightly doped emitter by using a laser with a wavelength greater than 450nm and a laser with a wavelength less than 450nm.
  • the preparation method of the selective emitter uses two or more wavelengths of lasers to sequentially pattern and dope boron atoms to the lightly doped emitter according to the characteristics of different wavelength lasers on the silicon thermal action depth.
  • the surface concentration and junction depth of the region can be precisely regulated to obtain a heavily doped selective emitter. While increasing the surface concentration of the heavily doped selective emitter, the junction depth is increased, thereby forming a laser region with high Doping concentrations and deep junctions, non-laser regions have selective emitter structures with low surface concentrations and shallow junctions.
  • the silicon wafer substrate is obtained after texturizing the surface of the silicon wafer.
  • the silicon slices include N-type silicon slices.
  • the preparation of a lightly doped emitter includes:
  • Diffusion treatment is performed on the silicon wafer substrate, and the lightly doped emitter is formed on the front surface of the silicon wafer substrate.
  • the surface concentration of the lightly doped emitter is (1E18-2E20) cm -3 , for example, 1E18cm -3 , 2E18cm -3 , 5E18cm -3 , 8E18cm -3 , 1E19cm -3 , 2E19cm -3 , 5E19cm -3 , 8E19cm -3 , 1E20cm -3 or 2E20cm -3 , other unlisted values within this range are also applicable.
  • E in this application means scientific notation, for example: “1E18” means 1 ⁇ 10 18 .
  • the junction depth of the lightly doped emitter is 0.1-2 ⁇ m, such as 0.1 ⁇ m, 0.2 ⁇ m, 0.3 ⁇ m, 0.4 ⁇ m, 0.5 ⁇ m, 0.6 ⁇ m, 0.7 ⁇ m, 0.8 ⁇ m, 0.9 ⁇ m, 1 ⁇ m, 1.1 ⁇ m, 1.2 ⁇ m, 1.3 ⁇ m, 1.4 ⁇ m, 1.5 ⁇ m, 1.6 ⁇ m, 1.7 ⁇ m, 1.8 ⁇ m, 1.9 ⁇ m or 2 ⁇ m, other unlisted values within this range are also applicable.
  • the square resistance of the lightly doped emitter is 100-500 ⁇ /sq, for example, it can be 100 ⁇ /sq, 120 ⁇ /sq, 150 ⁇ /sq, 180 ⁇ /sq, 200 ⁇ /sq, 220 ⁇ /sq, 250 ⁇ /sq , 280 ⁇ /sq, 300 ⁇ /sq, 320 ⁇ /sq, 350 ⁇ /sq, 380 ⁇ /sq, 400 ⁇ /sq, 420 ⁇ /sq, 450 ⁇ /sq, 480 ⁇ /sq or 500 ⁇ /sq. The same applies.
  • the surface of the lightly doped emitter is covered with the boron-rich layer.
  • the boron-rich layer has a thickness of 0.01-2 ⁇ m, for example, 0.01 ⁇ m, 0.1 ⁇ m, 0.2 ⁇ m, 0.3 ⁇ m, 0.4 ⁇ m, 0.5 ⁇ m, 0.6 ⁇ m, 0.7 ⁇ m, 0.8 ⁇ m, 0.9 ⁇ m, 1 ⁇ m, 1.1 ⁇ m, 1.2 ⁇ m, 1.3 ⁇ m, 1.4 ⁇ m, 1.5 ⁇ m, 1.6 ⁇ m, 1.7 ⁇ m, 1.8 ⁇ m, 1.9 ⁇ m or 2 ⁇ m, other unlisted values within this range are also applicable.
  • a boron source is provided in the diffusion furnace, so that the surface of the lightly doped selective emitter is covered with boron-rich layer.
  • the boron-rich layer on the surface of the lightly doped selective emitter can also be obtained by spin coating or screen printing.
  • APCVD Atmospheric Pressure Chemical Vapor Deposition
  • LPCVD Low Pressure Chemical Vapor Deposition
  • PECVD Plasma Enhanced Chemical Vapor Deposition
  • the method of chemical vapor deposition is reactive deposition to form a boron-rich layer.
  • this application does not require the structures of the diffusion furnace, the spin coating device and the vapor deposition device. Therefore, it can be understood that those skilled in the art can choose different types of diffusion furnaces, spin coating devices and vapor deposition devices according to usage scenarios, or make adaptive adjustments to the structures of diffusion furnaces, spin coating devices and vapor deposition devices.
  • the surface concentration of the heavily doped selective emitter is (3E18 ⁇ 1E22) cm -3 , for example, 3E18cm -3 , 5E18cm -3 , 8E18cm -3 , 1E19cm -3 , 2E19cm -3 , 5E19cm -3 3 , 8E19cm -3 , 1E20cm -3 , 5E20cm -3 , 8E20cm -3 , 1E21cm -3 , 2E21cm -3 , 5E21cm -3 , 8E21cm -3 or 1E22cm -3 , other unlisted values within this range are also applicable.
  • the junction depth of the heavily doped selective emitter is 0.2-5 ⁇ m, such as 0.2 ⁇ m, 0.5 ⁇ m, 0.8 ⁇ m, 1 ⁇ m, 1.2 ⁇ m, 1.5 ⁇ m, 1.8 ⁇ m, 2 ⁇ m, 2.3 ⁇ m, 2.5 ⁇ m , 2.8 ⁇ m, 3 ⁇ m, 3.2 ⁇ m, 3.5 ⁇ m, 3.8 ⁇ m, 4 ⁇ m, 4.2 ⁇ m, 4.5 ⁇ m, 4.8 ⁇ m or 5 ⁇ m, other unlisted values within this range are also applicable.
  • the square resistance of the heavily doped selective emitter is 20-200 ⁇ /sq, for example, it can be 20 ⁇ /sq, 40 ⁇ /sq, 60 ⁇ /sq, 80 ⁇ /sq, 100 ⁇ /sq, 120 ⁇ /sq, 140 ⁇ /sq, 160 ⁇ /sq, 180 ⁇ /sq or 200 ⁇ /sq, other unlisted values within this value range are also applicable.
  • the back side of the silicon wafer substrate is etched and cleaned sequentially, a tunneling layer and a doped polysilicon layer are deposited, wet chemical cleaning is performed sequentially, and the front side oxide layer is deposited.
  • a tunneling layer and a doped polysilicon layer are deposited, wet chemical cleaning is performed sequentially, and the front side oxide layer is deposited.
  • wet chemical cleaning is used to remove the polysilicon layer and boron-rich layer around the front side of the silicon wafer substrate.
  • the back surface of the silicon wafer substrate is etched and cleaned sequentially, a tunneling layer is deposited, a doped polysilicon layer is deposited, and a wet chemical cleaning is performed, followed by repeated steps.
  • the first wet chemical cleaning is used to remove the polysilicon layer on the front side of the silicon wafer substrate
  • the second wet chemical cleaning is used to remove the boron-rich layer and the laser damage layer on the front side of the silicon wafer substrate.
  • the operation steps for preparing the heavily doped selective emitter can be adjusted according to the actual situation, and the preparation of the laser doped heavily doped selective emitter can be carried out after the lightly doped emitter is prepared; After the tunneling layer and the doped polysilicon layer are prepared, the laser heavily doped selective emitter is prepared.
  • the tunneling layer includes any one of a silicon oxide layer, a silicon oxynitride layer, a silicon nitride layer or an aluminum oxide layer; the tunneling layer is deposited on a silicon substrate by means of thermal oxidation or chemical vapor deposition. bottom back.
  • said depositing a doped polysilicon layer includes:
  • a chemical vapor deposition method is used to deposit a doped amorphous silicon layer on the surface of the tunneling layer; the doped polysilicon layer is obtained by annealing and activating.
  • the intrinsic amorphous silicon layer can be deposited on the surface of the tunneling layer by low-pressure chemical vapor deposition or plasma-enhanced chemical vapor deposition, and then phosphorous is doped into the intrinsic amorphous silicon layer by a diffusion method
  • the doped amorphous silicon layer can be obtained after activation by high-temperature annealing; the doped amorphous silicon layer can also be deposited on the surface of the tunneling layer by low-pressure chemical vapor deposition or plasma-enhanced chemical vapor deposition.
  • the doped amorphous silicon layer is obtained after annealing and activation.
  • the front aluminum oxide layer is prepared by atomic layer deposition.
  • the double-sided passivation film layer includes a front passivation film layer and a back passivation film layer.
  • both the front passivation film layer and the back passivation film layer are prepared by plasma chemical vapor deposition.
  • the front passivation film layer is deposited on the surface of the front aluminum oxide layer.
  • the front passivation film layer includes any one or a combination of at least two of SiNx passivation film layer, silicon oxide passivation film layer or SiOxNy passivation film layer.
  • the back passivation film layer is deposited on the surface of the doped polysilicon layer.
  • the rear passivation film layer includes any one or a combination of at least two of SiNx passivation film layer, silicon oxide passivation film layer or SiOxNy passivation film layer.
  • the metal electrode is prepared by printing and sintering in sequence.
  • the metal electrodes include front metal electrodes and back metal electrodes.
  • the front metal electrode passes through the front passivation film layer and the front aluminum oxide layer, and the front metal electrode forms an ohmic contact with the heavily doped selective emitter.
  • the electrode grid line width of the front metal electrode is smaller than the width of the heavily doped selective emitter.
  • the front metal electrodes are printed with silver paste or silver-aluminum paste.
  • the back metal electrode is printed with silver paste.
  • the back metal electrode passes through the back passivation film layer to form an ohmic contact with the back doped polysilicon layer.
  • the present application provides a selective emitter battery, which is obtained by using the preparation method of the selective emitter battery described in the second aspect.
  • This embodiment provides a method for preparing a selective emitter battery as shown in Figure 1, the preparation method includes the following steps:
  • Boron source is added when the silicon wafer substrate 1 is diffused, so as to form a lightly doped surface with a surface concentration of 1E19cm -3 , a junction depth of 1 ⁇ m, and a square resistance of 300 ⁇ /sq on the front surface of the silicon wafer substrate 1 emitter 2, and form a boron-rich layer with a thickness of 0.1 ⁇ m on the surface of the lightly doped emitter 2;
  • a silicon oxide tunneling layer 7 is grown on the back side of the silicon wafer substrate 1 by thermal oxidation, and then deposited on the surface of the silicon oxide tunneling layer 7 with a thickness of Intrinsic amorphous silicon layer of 120nm, then phosphorus is doped into the intrinsic amorphous silicon layer by diffusion method, and annealed and activated at a temperature of 950°C to obtain doped polysilicon layer 8; followed by wet chemical cleaning, Removing the front polysilicon layer and the front boron-rich layer of the silicon wafer substrate 1;
  • the front aluminum oxide layer 4 and the front passivation film layer 5 are sequentially deposited on the surface of the lightly doped emitter 2 by plasma chemical vapor deposition, the front passivation film layer 5 is a SiNx passivation film layer, and the front aluminum oxide layer is The total thickness of layer 4 and SiNx passivation film layer is 80nm;
  • This embodiment provides a method for preparing a selective emitter battery as shown in Figure 1, the preparation method includes the following steps:
  • (2) Diffusion treatment is performed on the silicon wafer substrate 1 to form a lightly doped emitter 2 with a surface concentration of 1E18cm -3 , a junction depth of 2 ⁇ m, and a square resistance of 500 ⁇ /sq on the front surface of the silicon wafer substrate 1, and then adopt
  • the boron source is coated on the surface of the lightly doped emitter 2 by spin coating, and a boron-rich layer with a thickness of 2 ⁇ m is formed after drying;
  • a silicon oxide tunneling layer 7 and a doped amorphous silicon layer with a thickness of 100 nm are sequentially stacked on the back side of the silicon wafer substrate 1 by chemical vapor deposition, and at a temperature of 900° C. annealing and activating to obtain the doped polysilicon layer 8; followed by wet chemical cleaning to remove the front polysilicon layer and the front boron-rich layer of the silicon wafer substrate 1;
  • front passivation film layer 5 is SiNx passivation film layer, aluminum oxide layer and SiNx
  • the total thickness of the passivation film layer is 85nm
  • This embodiment provides a method for preparing a selective emitter battery as shown in Figure 1, the preparation method includes the following steps:
  • a silicon oxide tunneling layer 7 is grown on the back side of the silicon wafer substrate 1 by thermal oxidation, and then deposited on the surface of the silicon oxide tunneling layer 7 with a thickness of 120nm intrinsic amorphous silicon layer, then phosphorus is doped into the intrinsic amorphous silicon layer by diffusion method, and annealed and activated at a temperature of 900°C to obtain doped polysilicon layer 8; followed by wet chemical cleaning to remove Silicon wafer substrate 1 front polysilicon layer and front boron-rich layer;
  • front passivation film layer 5 is SiNx-silicon oxide passivation film layer, aluminum oxide
  • the total thickness of layer and SiNx-silicon oxide passivation film layer is 130nm;
  • Embodiments 1-3 use lasers of two wavelengths to sequentially pattern-dope the boron atoms in the boron-rich layer to the same area on the surface of the lightly doped emitter 2; wherein, in Embodiment 1 and Embodiment 3, the wavelengths less than A laser with a wavelength of 450nm and a laser with a wavelength greater than 450nm sequentially pattern-dope the boron atoms in the boron-rich layer to the same area on the surface of the lightly doped emitter 2; in embodiment 2, a laser with a wavelength greater than 450nm and a laser with a wavelength less than 450nm are used The boron atoms in the boron-rich layer are sequentially patterned and doped to the same area on the surface of the lightly doped emitter 2 .
  • the surface concentration and junction depth of the laser region can be precisely controlled to obtain the heavily doped selective emitter 3, so as to achieve the effect of increasing the surface concentration of the heavily doped selective emitter 3 and increasing the junction depth. Therefore, this application utilizes the characteristics that the surface of the boron-rich layer responds differently to lasers of different wavelengths, and uses two or more wavelengths of lasers to sequentially pattern boron atoms into the same area of the lightly doped emitter 2, which can control the laser
  • the surface concentration and junction depth of the region are precisely regulated to obtain the heavily doped selective emitter 3 , so that the junction depth can be increased while increasing the surface concentration of the heavily doped selective emitter 3 .
  • the emitter, the preparation method of the selective emitter battery and the selective emitter battery provided by the application utilize the characteristics that the surface of the boron-rich layer responds differently to lasers of different wavelengths and the depth of the heat action of different wavelengths of lasers on silicon is different.
  • Lasers with two wavelengths do boron doping on the surface of the silicon wafer, which can effectively adjust the concentration and depth of boron doping on the surface of the silicon wafer.
  • two or more wavelengths of lasers are used for patterned laser doping in sequence, which can precisely control the surface concentration and junction depth of the laser region to obtain heavy doping selectivity.
  • emitter thereby increasing the junction depth while increasing the surface concentration of the heavily doped selective emitter.
  • the preparation method of the selective emitter cell provided by the present application is simple and easy to operate, which can reduce the time cost of production, expand the process window, and promote the development of high-efficiency solar cell preparation technology.

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Abstract

本申请提供了发射极、选择性发射极电池的制备方法及选择性发射极电池，所述发射极的制备方法包括：采用至少两种不同波长的激光依次照射富硼层，依次将所述富硼层中的硼原子激光掺杂至硅片的同一区域，得到所述发射极。

Description

发射极、选择性发射极电池的制备方法及选择性发射极电池
本申请要求在2021年10月25日提交中国专利局、申请号为202111238759.X的中国专利申请的优先权，该申请的全部内容通过引用结合在本申请中。
技术领域
本申请属于太阳能电池技术领域，例如涉及发射极、选择性发射极电池的制备方法及选择性发射极电池。
背景技术
太阳电池中的选择性发射极是在金属栅线与硅片接触的区域进行重掺杂，而在硅片中非金属接触的区域进行轻掺杂的一种结构。这种结构能够降低金属接触区域的接触电阻，降低电池的串阻，同时轻掺杂区域能有效减少载流子复合，提高表面钝化。因此，选择性发射极结构的制备会提高电池的填充因子及电池的短波响应，最终提高电池的效率。
N型TOPCon电池被认为是钝化发射器和后部接触(Passivated Emitter and Rear Cell，PERC)电池升级的下一代产品，能够提升太阳电池效率。而正面硼扩选择性发射极结构是TOPCon电池提升电池效率的必备工艺，但相关技术中尚无低成本可量产的成熟工艺。相关技术中，多采用两步扩散、反刻、预沉积图形化硼源等制备TOPCon电池中的选择性发射电极，但经济性不高。而相关技术中的激光掺杂工艺很难将硼硅玻璃中的硼原子掺杂进入硅中，并且硼原子在氧化硅、硅中固溶度的不同，导致激光处理后的表面浓度大幅下降，虽然可以增加结深，但无法形成良好的欧姆接触。
CN109742172A公开了一种旋涂硼源激光掺杂制作N型选择性发射极双面电池的方法，制备方法包括：N型硅片制绒、正面采用旋涂法旋涂有机硼源后烘干、扩散炉中扩散形成正面轻掺杂发射极、正面硼硅玻璃(BSG)激光掺杂形成重掺杂选择性发射极、背面清洗去二氧化硅玻璃(PSG)、背面磷扩散形成磷背场、正反面沉积减反射钝化膜、印刷正背面金属电极完成电池制作。
CN112670353A公开了一种硼掺杂选择性发射极电池及其制备方法，所述选择性发射极电池包括N型晶硅、设于所述N型晶硅正面的两个正电极和设于所述N型晶硅背面的两个负电极，所述N型晶硅的背面设有SiO 2层，所述SiO 2层上设有P掺杂多晶硅层。同时，其公开了采用硼浆印刷+激光推进的方式制备选择性硼SE结构。
CN113035976A公开了硼掺杂选择性发射极及制法、硼掺杂选择性发射极电池，制备方法包括：在制绒后硅片的表面制备重掺杂区和轻掺杂区，先在硅片表面覆盖一层硼掺杂剂，硼掺杂剂的覆盖区域不小于重掺杂区的区域大小；再对位于重掺杂区的硼掺杂剂进行激光掺杂形成硼化硅；然后对硼化硅进行高温推进，形成重掺杂区；接着在硅片表面形成轻掺杂区制得硼掺杂选择性发射极。
上述文献虽然从不同方面对选择性发射电极制备工艺进行改进，但激光掺杂工艺仍然很难将BSG中的硼源掺杂进P+层中，并且使用激光掺杂后会同时改变原有硅片表面浓度及结深，即降低表面浓度，增加结深。
发明内容
本申请提供发射极、选择性发射极电池的制备方法及选择性发射极电池，采用至少两种波长的激光对硅片表面进行硼掺杂，可以有效调节硅片表面的硼掺杂浓度和深度。
第一方面，本申请提供了一种发射极的制备方法，所述发射极的制备方法包括：采用至少两种不同波长的激光依次照射富硼层，以依次将所述富硼层中的硼原子掺杂至硅片的同一区域，得到所述发射极。
第二方面，本申请提供了一种选择性发射极电池的制备方法，所述制备方法包括：对硅片进行制绒、制备轻掺杂发射极和富硼层、制备重掺杂选择性发射极和制备金属电极，得到所述选择性发射极电池。
其中，所述重掺杂选择性发射极根据第一方面所述的发射极的制备方法制备得到，第一次激光掺杂和第二次激光掺杂将所述富硼层中的硼原子依次图案化掺杂至所述轻掺杂发射极表面的同一区域，得到所述重掺杂选择性发射极，所述重掺杂选择性发射极嵌入所述轻掺杂发射极。
第三方面，本申请提供了一种选择性发射极电池，所述选择性发射极电池采用第二方面所述的选择性发射极电池的制备方法得到。
附图说明
图1为本申请提供的选择性发射极电池的结构示意图。
其中，1-硅片衬底；2-轻掺杂发射极；3-重掺杂选择性发射极；4-正面氧化铝层；5-正面钝化膜层；6-正面金属电极；7-隧穿层；8-掺杂多晶硅层；9-背面钝化膜层；10-背面金属电极。
具体实施方式
需要理解的是，在本申请的描述中，术语“中心”、“纵向”、“横向”、“上”、“下”、“前”、“后”、“左”、“右”、“竖直”、“水平”、“顶”、“底”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作。此外，术语“第一”、“第二”等仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”等的特征可以明示或者隐含地包括一个或者更多个该特征。在本申请的描述中，除非另有说明，“多个”的含义是两个或两个以上。
需要说明的是，在本申请的描述中，除非另有明确的规定，术语“设置”、“相连”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体连接；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通。对于本领域的普通技术人员而言，可以通过具体情况理解上述术语在本申请中的具体含义。
下面结合附图并通过具体实施方式来说明本申请。
本申请提供发射极、选择性发射极电池的制备方法及选择性发射极电池，利用富硼层表面对不同波段的激光响应不同，以及不同波长激光对硅热作用深度不同的特点，采用至少两种波长的激光对硅片表面进行硼掺杂，可以有效调节硅片表面的硼掺杂浓度和深度。同时，在制备选择性发射极电池的过程中，采用两种或两种以上波长的激光依次进行图案化激光掺杂，可以对激光区域的表面浓度及结深进行精准调控得到重掺杂选择性发射极，从而在提高重掺杂选择性发射极的表面浓度的同时，增加结深。此外，本申请提供的选择性发射极电池的制备方法简便、操作方便，能够降低生产的时间成本，开拓工艺窗口，推进高效太阳电池制备技术的发展。
第一方面，本申请提供了一种发射极的制备方法，所述发射极的制备方法包括：采用至少两种不同波长的激光依次照射富硼层，依次将所述富硼层中的硼原子掺杂至硅片的同一区域，得到所述发射极。
本申请提供的发射极的制备方法，利用富硼层表面对不同波段的激光响应不同，以及不同波长激光对硅热作用深度不同的特点，采用至少两种波长的激光对硅片表面进行硼掺杂，可以有效调节硅片表面的硼掺杂浓度和深度。
优选地，所述依次采用至少两种不同波长的激光依次照射富硼层，包括：采用第一激光照射富硼层后，采用第二激光照射富硼层。
优选地，所述第一激光的波长＜450nm，例如可以是440nm、420nm、400nm、380nm、350nm、320nm、300nm、280nm、250nm、220nm、200nm、180nm、150nm或100nm；所述第二激光的波长＞450nm，例如可以是460nm、500nm、550nm、600nm、650nm、700nm、750nm、800nm、850nm、900nm、950nm、1000nm或1200nm；该数值范围内其他未列举的数值同样适用。
优选地，所述依次采用至少两种不同波长的激光依次照射富硼层，包括：采用第一激光照射富硼层后，采用第二激光照射富硼层。
优选地，所述第一激光的波长＞450nm，例如可以是460nm、500nm、550nm、600nm、650nm、700nm、750nm、800nm、850nm、900nm、950nm、1000nm或1200nm；所述第二激光的波长＜450nm，例如可以是440nm、420nm、400nm、380nm、350nm、320nm、300nm、280nm、250nm、220nm、200nm、180nm、150nm或100nm；该数值范围内其他未列举的数值同样适用。
本申请提供了激光掺杂制备发射极的两种方案：(1)采用波长小于450nm的激光和波长大于450nm的激光依次将富硼层中的硼原子掺杂至硅片表面的同一区域；(2)采用波长大于450nm的激光和波长小于450nm的激光依次将富硼层中的硼原子掺杂至硅片表面的同一区域。
第二方面，本申请提供了一种选择性发射极电池的制备方法，所述制备方法包括：对硅片进行制绒、制备轻掺杂发射极和富硼层、制备重掺杂选择性发射极和制备金属电极，得到所述选择性发射极电池。
其中，所述重掺杂选择性发射极根据第一方面所述的发射极的制备方法制备得到，第一次激光掺杂和第二次激光掺杂将所述富硼层中的硼原子依次图案化掺杂至所述轻掺杂发射极表面的同一区域，得到所述重掺杂选择性发射极，所述重掺杂选择性发射极嵌入所述轻掺杂发射极。
本申请提供了激光掺杂制备重掺杂选择性发射极的两种方案：(1)采用波长小于450nm的激光和波长大于450nm的激光依次将富硼层中的硼原子图案化掺杂至轻掺杂发射极表面的同一区域；(2)采用波长大于450nm的激光和波长小于450nm的激光依次将富硼层中的硼原子图案化掺杂至轻掺杂发射极表面的同一区域。
本申请提供的选择性发射极的制备方法，根据不同波长激光对硅热作用深度不同的特点，采用两种或两种以上波长的激光将硼原子依次图案化掺杂至轻掺杂发射极的同一区域，可以对该区域的表面浓度及结深进行精准调控得到重掺杂选择性发射极，在提高重掺杂选择性发射极的表面浓度的同时，增加结深，从而形成激光区域具有高掺杂浓度和深结，非激光区域具有低表面浓度和浅结 的选择性发射极结构。
优选地，所述硅片的表面制绒处理后得到硅片衬底。
优选地，所述硅片包括N型硅片。
优选地，所述制备轻掺杂发射极，包括：
对所述硅片衬底进行扩散处理，在所述硅片衬底的正面形成所述轻掺杂发射极。
优选地，所述轻掺杂发射极的表面浓度为(1E18～2E20)cm -3，例如可以是1E18cm -3、2E18cm -3、5E18cm -3、8E18cm -3、1E19cm -3、2E19cm -3、5E19cm -3、8E19cm -3、1E20cm -3或2E20cm -3，该数值范围内其他未列举的数值同样适用。
需要说明的是，本申请中的“E”表示科学计数法，比如：“1E18”是指1×10 18。
优选地，所述轻掺杂发射极的结深为0.1～2μm，例如可以是0.1μm、0.2μm、0.3μm、0.4μm、0.5μm、0.6μm、0.7μm、0.8μm、0.9μm、1μm、1.1μm、1.2μm、1.3μm、1.4μm、1.5μm、1.6μm、1.7μm、1.8μm、1.9μm或2μm，该数值范围内其他未列举的数值同样适用。
优选地，所述轻掺杂发射极的方阻为100～500Ω/sq，例如可以是100Ω/sq、120Ω/sq、150Ω/sq、180Ω/sq、200Ω/sq、220Ω/sq、250Ω/sq、280Ω/sq、300Ω/sq、320Ω/sq、350Ω/sq、380Ω/sq、400Ω/sq、420Ω/sq、450Ω/sq、480Ω/sq或500Ω/sq，该数值范围内其他未列举的数值同样适用。
优选地，所述轻掺杂发射极的表面包覆有所述富硼层。
优选地，所述富硼层的厚度为0.01～2μm，例如可以是0.01μm、0.1μm、0.2μm、0.3μm、0.4μm、0.5μm、0.6μm、0.7μm、0.8μm、0.9μm、1μm、1.1μm、1.2μm、1.3μm、1.4μm、1.5μm、1.6μm、1.7μm、1.8μm、1.9μm或2μm，该数值范围内其他未列举的数值同样适用。
本申请中，在硅片衬底放入扩散炉中进行扩散制备得到轻掺杂选择性发射极的同时，在扩散炉中提供硼源，从而在轻掺杂选择性发射极的表面覆盖富硼层。此外，也可以通过旋涂或丝网印刷方法得到轻掺杂选择性发射极表面的富硼层。另外，也可以通过常压化学气相沉积(Atmospheric Pressure Chemical Vapor Deposition，APCVD)、低压化学气相沉积(Low Pressure Chemical Vapor Deposition，LPCVD)、等离子体增强化学气相沉积(Plasma Enhanced Chemical Vapor Deposition，PECVD)等化学气相沉积的方法反应沉积形成富硼层。
需要说明的是，本申请对扩散炉、旋涂装置和气相沉积装置的结构不作要 求。因此可以理解的是，本领域技术人员可以根据使用场景选择不同类型的扩散炉、旋涂装置和气相沉积装置，或对扩散炉、旋涂装置和气相沉积装置的结构进行适应性调整。
优选地，所述重掺杂选择性发射极的表面浓度为(3E18～1E22)cm -3，例如可以是3E18cm -3、5E18cm -3、8E18cm -3、1E19cm -3、2E19cm -3、5E19cm -3、8E19cm -3、1E20cm -3、5E20cm -3、8E20cm -3、1E21cm -3、2E21cm -3、5E21cm -3、8E21cm -3或1E22cm -3，该数值范围内其他未列举的数值同样适用。
优选地，所述重掺杂选择性发射极的结深为0.2～5μm，例如可以是0.2μm、0.5μm、0.8μm、1μm、1.2μm、1.5μm、1.8μm、2μm、2.3μm、2.5μm、2.8μm、3μm、3.2μm、3.5μm、3.8μm、4μm、4.2μm、4.5μm、4.8μm或5μm，该数值范围内其他未列举的数值同样适用。
优选地，所述重掺杂选择性发射极的方阻为20～200Ω/sq，例如可以是20Ω/sq、40Ω/sq、60Ω/sq、80Ω/sq、100Ω/sq、120Ω/sq、140Ω/sq、160Ω/sq、180Ω/sq或200Ω/sq，该数值范围内其他未列举的数值同样适用。
优选地，在制备所述重掺杂选择性发射极后，对所述硅片衬底的背面依次进行刻蚀清洗，沉积隧穿层和掺杂多晶硅层，依次进行湿化学清洗，沉积正面氧化铝层、沉积双面钝化膜层和双面金属的制备。
此时，湿法化学清洗用于去除所述硅片衬底正面绕度的多晶硅层和富硼层。
优选地，制备所述轻掺杂选择性发射极后，对所述硅片衬底的背面依次进行刻蚀清洗，沉积隧穿层、沉积掺杂多晶硅层和一次湿化学清洗，随后依次进行重掺杂选择性发射极、二次湿化学清洗、沉积正面氧化铝层、沉积双面钝化膜层和双面金属电极的制备。
此时，一次湿化学清洗用于去除硅片衬底正面的多晶硅层，二次湿化学清洗用于去除硅片衬底正面的富硼层及激光损伤层。
本申请中，对制备重掺杂选择性发射极的操作步骤可以根据实际情况进行调整，可以在制备轻掺杂发射极后进行激光掺杂重掺杂选择性发射极的制备；也可以在完成隧穿层和掺杂多晶硅层的制备后，再进行激光重掺杂选择性发射极的制备。
本申请中，隧穿层包括氧化硅层、氮氧化硅层、氮化硅层或氧化铝层中的任意一种；采用热氧化或化学气相沉积的等方式将隧穿层沉积于硅片衬底的背面。
优选地，所述沉积掺杂多晶硅层，包括：
采用化学气相沉积法将本征非晶硅层沉积至所述隧穿层的表面，通过扩散法将磷掺杂于所述本征非晶硅层内得到掺杂的非晶硅层；
或，采用化学气相沉积法将掺杂的非晶硅层沉积至所述隧穿层的表面；通过退火激活得到所述掺杂多晶硅层。
本申请中，可以采用低压化学气相沉积法或等离子增强化学气相沉积法将本征非晶硅层沉积到隧穿层的表面，随后通过扩散法将磷掺杂于所述本征非晶硅层内，并通过高温退火激活后得到所述掺杂非晶硅层；也可以采用低压化学气相沉积法或等离子增强化学气相沉积法将掺杂非晶硅层沉积到隧穿层的表面，通过高温退火激活后得到所述掺杂非晶硅层。
优选地，所述正面氧化铝层采用原子层沉积制备得到。
优选地，所述双面钝化膜层包括正面钝化膜层和背面钝化膜层。
优选地，所述正面钝化膜层和背面钝化膜层均采用等离子体化学气相沉积制备得到。
优选地，所述正面钝化膜层沉积在所述正面氧化铝层的表面。
本申请中，正面钝化膜层包括SiNx钝化膜层、氧化硅钝化膜层或SiOxNy钝化膜层中的任意一种或至少两种的组合。
优选地，所述背面钝化膜层沉积在所述掺杂多晶硅层的表面。
本申请中，背面钝化膜层包括SiNx钝化膜层、氧化硅钝化膜层或SiOxNy钝化膜层中的任意一种或至少两种的组合。
优选地，所述金属电极依次通过印刷和烧结制备得到。
优选地，所述金属电极包括正面金属电极和背面金属电极。
优选地，所述正面金属电极穿过所述正面钝化膜层和正面氧化铝层，所述正面金属电极与重掺杂选择性发射极形成欧姆接触。
优选地，所述正面金属电极的电极栅线宽度小于所述重掺杂选择性发射极宽度。
优选地，所述正面金属电极采用银浆或银铝浆印刷方式。
优选地，所述背面金属电极采用银浆印刷方式。
优选地，所述背面金属电极穿过所述背面钝化膜层与所述背面掺杂多晶硅层形成欧姆接触。
第三方面，本申请提供了一种选择性发射极电池，所述选择性发射极电池采用第二方面所述的选择性发射极电池的制备方法得到。
实施例1
本实施例提供了一种如图1所示的选择性发射极电池的制备方法，所述制备方法包括如下步骤：
(1)对N型硅片的表面进行制绒清洗处理，得到硅片衬底1；
(2)在对硅片衬底1进行扩散处理时添加硼源，从而在硅片衬底1的正面形成表面浓度为1E19cm -3，结深为1μm，方阻为300Ω/sq的轻掺杂发射极2，并在轻掺杂发射极2的表面形成厚度为0.1μm的富硼层；
(3)首先采用波长325nm的紫外激光将富硼层中的硼原子图案化掺杂至轻掺杂发射极2，随后采用波长532nm的绿激光将富硼层中的硼原子图案化掺杂至轻掺杂发射极2的同一区域，得到表面浓度为2E20cm -3，结深为3μm，方阻为90Ω/sq的重掺杂选择性发射极3；
(4)对硅片衬底1的背面进行刻蚀，去除背面绕扩，并重新抛光制绒，清洗表面；
(5)通过热氧化的方式在硅片衬底1的背面生长氧化硅隧穿层7，然后在沉积温度为600℃下，采用化学气相沉积法在氧化硅隧穿层7的表面沉积厚度为120nm的本征非晶硅层，然后通过扩散法将磷掺杂于本征非晶硅层内，并在950℃的温度下进行退火激活，得到掺杂多晶硅层8；随后进行湿化学清洗，去除硅片衬底1正面多晶硅层和正面富硼层；
(6)采用等离子体化学气相沉积法在轻掺杂发射极2的表面依次沉积正面氧化铝层4和正面钝化膜层5，正面钝化膜层5为SiNx钝化膜层，正面氧化铝层4和SiNx钝化膜层的总厚度为80nm；
(7)采用等离子体化学气相沉积法在掺杂多晶硅层8的表面沉积厚度为75nm的背面钝化膜层9，背面钝化膜层9为SiNx钝化膜层；
(8)依次采用银铝浆印刷和烧结得到正面金属电极6，其中正面金属电极6的电极栅线宽度小于重掺杂选择性发射极3宽度；依次采用银浆印刷和烧结得到背面金属电极10，从而得到所述选择性发射极电池。
实施例2
本实施例提供了一种如图1所示的选择性发射极电池的制备方法，所述制备方法包括如下步骤：
(1)对N型硅片的表面进行制绒清洗处理，得到硅片衬底1；
(2)对硅片衬底1进行扩散处理，在硅片衬底1的正面形成表面浓度为1E18cm -3，结深为2μm，方阻为500Ω/sq的轻掺杂发射极2，随后采用旋涂法将 硼源涂覆在轻掺杂发射极2的表面，干燥后形成厚度为2μm的富硼层；
(3)首先采用波长1064nm的红外激光将富硼层中的硼原子图案化掺杂至轻掺杂发射极2，随后采用波长325nm的紫外激光将富硼层中的硼原子图案化掺杂至轻掺杂发射极2的同一区域，得到表面浓度为3E18cm -3，结深为5μm，方阻为200Ω/sq的重掺杂选择性发射极3；
(4)对硅片衬底1的背面进行刻蚀，去除背面绕扩，并重新抛光制绒，清洗表面；
(5)在450℃的温度下，通过化学气相沉积法在硅片衬底1的背面依次层叠制备氧化硅隧穿层7和厚度为100nm掺杂的非晶硅层，并在900℃的温度下进行退火激活，得到掺杂多晶硅层8；随后进行湿化学清洗，去除硅片衬底1正面多晶硅层和正面富硼层；
(6)采用等离子体化学气相沉积法在轻掺杂发射极2的表面依次沉积氧化铝层和正面钝化膜层5，正面钝化膜层5为SiNx钝化膜层，氧化铝层和SiNx钝化膜层的总厚度为85nm；
(7)采用等离子体化学气相沉积法在掺杂多晶硅层8的表面沉积厚度为65nm的背面钝化膜层9，背面钝化膜层9为SiNx钝化膜层；
(8)依次采用银铝浆印刷和烧结得到正面金属电极6，其中正面金属电极6的电极栅线宽度小于重掺杂选择性发射极3宽度；依次采用银浆印刷和烧结得到背面金属电极10，从而得到所述选择性发射极电池。
实施例3
本实施例提供了一种如图1所示的选择性发射极电池的制备方法，所述制备方法包括如下步骤：
(1)对N型硅片的表面进行制绒清洗处理，得到硅片衬底1；
(2)在对硅片衬底1进行扩散处理时添加硼源，从而在硅片衬底1的正面形成表面浓度为2E20cm -3，结深为0.1μm，方阻为100Ω/sq的轻掺杂发射极2，并在轻掺杂发射极2的表面形成厚度为0.01μm的富硼层；
(3)对硅片衬底1背面进行进行刻蚀，去除背面绕扩，并重新抛光制绒，清洗表面；
(4)通过热氧化的方式在硅片衬底1的背面生长氧化硅隧穿层7，然后在沉积温度为600℃下，采用化学气相沉积法在氧化硅隧穿层7的表面沉积厚度为120nm本征非晶硅层，然后通过扩散法将磷掺杂于本征非晶硅层内，并在900℃的温度下进行退火激活，得到掺杂多晶硅层8；随后进行湿化学清洗，去除硅片 衬底1正面多晶硅层和正面富硼层；
(5)采用波长325nm的紫外激光将富硼层中的硼原子图案化掺杂至轻掺杂发射极2，随后采用波长1064nm的红外激光将富硼层中的硼原子图案化掺杂至轻掺杂发射极2的同一区域，得到表面浓度为1E22cm -3，结深为0.2μm，方阻为20Ω/sq的重掺杂选择性发射极3；随后进行湿化学清洗，去除硅片衬底1正面的富硼层及激光损伤层。
(6)采用等离子体化学气相沉积法在轻掺杂发射极2的表面依次沉积氧化铝层和正面钝化膜层5，正面钝化膜层5为SiNx-氧化硅钝化膜层，氧化铝层和SiNx-氧化硅钝化膜层的总厚度为130nm；
(7)采用等离子体化学气相沉积法在掺杂多晶硅层8的表面沉积厚度为65nm的背面钝化膜层9，背面钝化膜层9为SiNx钝化膜层；
(8)依次采用银铝浆印刷和烧结得到正面金属电极6，其中正面金属电极6的电极栅线宽度小于重掺杂选择性发射极3宽度；依次采用银浆印刷和烧结得到背面金属电极10，从而得到所述选择性发射极电池。
实施例1-3采用两种波长的激光依次将富硼层中的硼原子图案化掺杂至轻掺杂发射极2表面的同一区域；其中，实施例1和实施例3中均采用波长小于450nm的激光和波长大于450nm的激光依次将富硼层中的硼原子图案化掺杂至轻掺杂发射极2表面的同一区域；实施例2中采用波长大于450nm的激光和波长小于450nm的激光依次将富硼层中的硼原子图案化掺杂至轻掺杂发射极2表面的同一区域。实施例1-3均可以对激光区域的表面浓度及结深进行精准调控得到重掺杂选择性发射极3，达到提高重掺杂选择性发射极3的表面浓度，并且增加结深的效果。因此，本申请利用富硼层表面对不同波段激光响应不同的特点，采用两种或两种以上波长的激光将硼原子依次图案化掺杂至轻掺杂发射极2的同一区域，可以对激光区域的表面浓度及结深进行精准调控得到重掺杂选择性发射极3，从而实现了在提高重掺杂选择性发射极3的表面浓度的同时增加结深。
本申请提供的发射极、选择性发射极电池的制备方法及选择性发射极电池，利用富硼层表面对不同波段的激光响应不同，以及不同波长激光对硅热作用深度不同的特点，采用至少两种波长的激光对硅片表面进行硼掺杂，可以有效调节硅片表面的硼掺杂浓度和深度。同时，在制备选择性发射极电池的过程中，采用两种或两种以上波长的激光依次进行图案化激光掺杂，可以对激光区域的表面浓度及结深进行精准调控得到重掺杂选择性发射极，从而在提高重掺杂选择性发射极的表面浓度的同时，增加结深。此外，本申请提供的选择性发射极电池的制备方法简便、操作方便，能够降低生产的时间成本，开拓工艺窗口，推进高效太阳电池制备技术的发展。

Claims (10)

  1. 一种发射极的制备方法，包括：
    采用至少两种不同波长的激光依次照射富硼层，以依次将所述富硼层中的硼原子掺杂至硅片的同一区域，得到所述发射极。
  2. 根据权利要求1所述的发射极的制备方法，其中，所述采用至少两种不同波长的激光依次照射富硼层，包括：采用第一激光照射富硼层后，采用第二激光照射富硼层；
    优选地，所述第一激光的波长＜450nm，所述第二激光的波长＞450nm。
  3. 根据权利要求1所述的发射极的制备方法，其中，所述采用至少两种不同波长的激光依次照射富硼层，包括：采用第一激光照射富硼层后，采用第二激光照射富硼层；
    优选地，所述第一激光的波长＞450nm，所述第二激光的波长＜450nm。
  4. 一种选择性发射极电池的制备方法，包括：
    对硅片进行制绒、制备轻掺杂发射极和富硼层、制备重掺杂选择性发射极和制备金属电极，得到所述选择性发射极电池；
    其中，所述重掺杂选择性发射极根据权利要求1-3任一项所述的发射极的制备方法制备得到，第一次激光掺杂和第二次激光掺杂将所述富硼层中的硼原子依次图案化掺杂至所述轻掺杂发射极表面的同一区域，得到所述重掺杂选择性发射极，所述重掺杂选择性发射极嵌入所述轻掺杂发射极。
  5. 根据权利要求4所述的选择性发射极电池的制备方法，其中，所述硅片的表面制绒处理后得到硅片衬底；
    优选地，所述硅片包括N型硅片；
    优选地，所述制备轻掺杂发射极，包括：
    对所述硅片衬底进行扩散处理，在所述硅片衬底的正面形成所述轻掺杂发射极；
    优选地，所述轻掺杂发射极的表面浓度为(1E18～2E20)cm -3；
    优选地，所述轻掺杂发射极的结深为0.1～2μm；
    优选地，所述轻掺杂发射极的方阻为100～500Ω/sq；
    优选地，所述轻掺杂发射极的表面包覆有所述富硼层；
    优选地，所述富硼层的厚度为0.01～2μm；
    优选地，所述重掺杂选择性发射极的表面浓度为(3E18～1E22)cm -3；
    优选地，所述重掺杂选择性发射极的结深为0.2～5μm；
    优选地，所述重掺杂选择性发射极的方阻为20～200Ω/sq。
  6. 根据权利要求4或5所述的选择性发射极电池的制备方法，在制备所述重掺杂选择性发射极后，还包括：
    对所述硅片衬底的背面依次进行刻蚀清洗，沉积隧穿层和掺杂多晶硅层，依次进行湿化学清洗，沉积正面氧化铝层、沉积双面钝化膜层和双面金属电极的制备。
  7. 根据权利要求4或5所述的选择性发射极电池的制备方法，在制备所述轻掺杂选择性发射极后，还包括：
    对所述硅片衬底的背面依次进行刻蚀清洗，沉积隧穿层、沉积掺杂多晶硅层和一次湿化学清洗，依次进行重掺杂选择性发射极、二次湿化学清洗、沉积正面氧化铝层、沉积双面钝化膜层和双面金属电极的制备。
  8. 根据权利要求6或7所述的选择性发射极电池的制备方法，其中，所述沉积掺杂多晶硅层，包括：
    采用化学气相沉积法将本征非晶硅层沉积至所述隧穿层的表面，通过扩散法将磷掺杂于所述本征非晶硅层内得到掺杂的非晶硅层；
    或，采用化学气相沉积法将掺杂的非晶硅层沉积至所述隧穿层的表面；通过退火激活得到所述掺杂多晶硅层；
    优选地，所述正面氧化铝层采用原子层沉积制备得到；
    优选地，所述双面钝化膜层包括正面钝化膜层和背面钝化膜层；
    优选地，所述正面钝化膜层和背面钝化膜层均采用等离子体化学气相沉积制备得到；
    优选地，所述正面钝化膜层沉积在所述正面氧化铝层的表面；
    优选地，所述背面钝化膜层沉积在所述掺杂多晶硅层的表面。
  9. 根据权利要求4-8任一项所述的选择性发射极电池的制备方法，其中，所述金属电极依次通过印刷和烧结制备得到；
    优选地，所述金属电极包括正面金属电极和背面金属电极；
    优选地，所述正面金属电极穿过所述正面钝化膜层和正面氧化铝层，所述正面金属电极与重掺杂选择性发射极形成欧姆接触；
    优选地，所述正面金属电极的电极栅线宽度小于所述重掺杂选择性发射极宽度；
    优选地，所述正面金属电极采用银浆或银铝浆印刷方式；
    优选地，所述背面金属电极采用银浆印刷方式；
    优选地，所述背面金属电极穿过所述背面钝化膜层与所述背面掺杂多晶硅层形成欧姆接触。
  10. 一种选择性发射极电池，采用权利要求5-9任一项所述的选择性发射极电池的制备方法得到。
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CN117317065A (zh) * 2023-11-28 2023-12-29 苏州腾晖光伏技术有限公司 单晶太阳能电池制备设备
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