CN117199190A - Manufacturing method of N-TOPCON battery - Google Patents
Manufacturing method of N-TOPCON battery Download PDFInfo
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- CN117199190A CN117199190A CN202311273569.0A CN202311273569A CN117199190A CN 117199190 A CN117199190 A CN 117199190A CN 202311273569 A CN202311273569 A CN 202311273569A CN 117199190 A CN117199190 A CN 117199190A
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 19
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 188
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 188
- 239000010703 silicon Substances 0.000 claims abstract description 188
- 239000000758 substrate Substances 0.000 claims abstract description 168
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 80
- 229920005591 polysilicon Polymers 0.000 claims abstract description 75
- 238000000034 method Methods 0.000 claims abstract description 65
- 229910052814 silicon oxide Inorganic materials 0.000 claims abstract description 53
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 46
- 239000005388 borosilicate glass Substances 0.000 claims description 37
- 239000005360 phosphosilicate glass Substances 0.000 claims description 28
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 23
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 22
- 229910052760 oxygen Inorganic materials 0.000 claims description 22
- 239000001301 oxygen Substances 0.000 claims description 22
- 238000005406 washing Methods 0.000 claims description 18
- 238000009792 diffusion process Methods 0.000 claims description 17
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 16
- 229910052796 boron Inorganic materials 0.000 claims description 16
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 15
- 229910052698 phosphorus Inorganic materials 0.000 claims description 15
- 239000011574 phosphorus Substances 0.000 claims description 15
- 239000012535 impurity Substances 0.000 claims description 10
- 239000002253 acid Substances 0.000 claims description 9
- 239000007789 gas Substances 0.000 claims description 8
- 238000013532 laser treatment Methods 0.000 claims description 7
- 238000005498 polishing Methods 0.000 claims description 7
- 238000004140 cleaning Methods 0.000 claims description 4
- 230000005641 tunneling Effects 0.000 abstract description 21
- 238000007254 oxidation reaction Methods 0.000 abstract description 11
- 230000008569 process Effects 0.000 abstract description 10
- 230000003647 oxidation Effects 0.000 abstract description 9
- 238000002161 passivation Methods 0.000 abstract description 9
- 230000000694 effects Effects 0.000 abstract description 5
- 238000005516 engineering process Methods 0.000 abstract description 3
- 238000004093 laser heating Methods 0.000 abstract description 3
- 239000000463 material Substances 0.000 abstract description 2
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 24
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 22
- 238000000151 deposition Methods 0.000 description 20
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 19
- 230000008021 deposition Effects 0.000 description 15
- 238000005554 pickling Methods 0.000 description 11
- 238000004518 low pressure chemical vapour deposition Methods 0.000 description 10
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 9
- 229910052709 silver Inorganic materials 0.000 description 9
- 239000004332 silver Substances 0.000 description 9
- 238000000231 atomic layer deposition Methods 0.000 description 7
- 238000011282 treatment Methods 0.000 description 6
- 238000007639 printing Methods 0.000 description 5
- 238000005215 recombination Methods 0.000 description 5
- 230000006798 recombination Effects 0.000 description 5
- 238000005245 sintering Methods 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 239000003513 alkali Substances 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 239000011521 glass Substances 0.000 description 4
- 239000003518 caustics Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000010301 surface-oxidation reaction Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- ILAHWRKJUDSMFH-UHFFFAOYSA-N boron tribromide Chemical compound BrB(Br)Br ILAHWRKJUDSMFH-UHFFFAOYSA-N 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 229910015845 BBr3 Inorganic materials 0.000 description 1
- 229910015844 BCl3 Inorganic materials 0.000 description 1
- 101100409194 Rattus norvegicus Ppargc1b gene Proteins 0.000 description 1
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- 239000002131 composite material Substances 0.000 description 1
- 229910021419 crystalline silicon Inorganic materials 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
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- 230000006872 improvement Effects 0.000 description 1
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- 230000007246 mechanism Effects 0.000 description 1
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- 238000011056 performance test Methods 0.000 description 1
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- 239000010453 quartz Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- FAQYAMRNWDIXMY-UHFFFAOYSA-N trichloroborane Chemical compound ClB(Cl)Cl FAQYAMRNWDIXMY-UHFFFAOYSA-N 0.000 description 1
- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 description 1
Classifications
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- 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
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Abstract
The application discloses a manufacturing method of an N-TOPCON battery, which fully utilizes passivation and contact technology of the N-TOPCON battery, and on the prior polysilicon structure, a tunneling silicon oxide layer with stable thickness and compactness is formed by laser heating and oxidation on the back surface of an N-type silicon substrate. The application does not use expensive materials or complex process methods, so the application has larger mass production practicability, has obvious effect on improving efficiency and greatly reduces production cost.
Description
Technical Field
The application relates to the technical field of solar cells, in particular to a manufacturing method of an N-TOPCON cell.
Background
With the gradual depletion of conventional energy, solar energy is definitely the most common, cleanest and most potential alternative energy among the current sustainable energy, the development and utilization of solar energy are particularly important, and a solar power generation device is also called a photovoltaic cell or a solar battery, and the power generation principle is based on the photovoltaic effect of a semiconductor PN junction, so that solar energy can be directly converted into a battery.
The tunneling oxide passivation contact (Tunnel Oxide Passivated Contact, TOPCon) solar cell is a high-efficiency solar cell technology for passivation contact of a tunneling silicon oxide layer based on a selective carrier principle, and is one of methods for realizing high efficiency in a crystalline silicon solar cell production process. In recent years, with the continuous expansion of the capacity of the TOPCO battery, the TOPCO battery assembly is increasingly favored by market terminals because the double-sided battery structure of the TOPCO battery has higher conversion efficiency and double-sided rate than the perc battery, and can effectively reduce the installation cost of the power station.
The TOPCON battery is used for preparing an ultrathin silicon oxide layer on the back of the battery, then a thin doped silicon layer is deposited, and the silicon oxide layer and the doped silicon layer jointly form a passivation contact structure, so that surface recombination and metal contact recombination are effectively reduced, the open-circuit voltage of the solar battery is improved, and the conversion efficiency of the solar battery is improved. Therefore, the uniform tunneling ultrathin silicon oxide layer has good guarantee on tunneling and passivation, and the efficiency is improved more stably. However, stability in terms of efficiency of the TOPCon battery still has some problems at present, and especially stability of thickness and uniformity of the silicon oxide layer is poor due to the introduction of the tunneling ultrathin silicon oxide layer on the back of the battery, so that development of an efficient and stable back tunneling silicon oxide layer passivation battery is urgent.
At present, TOPCon batteries are grown at high temperatureIn the form of (a) a Low Pressure Chemical Vapor Deposition (LPCVD) process, the polysilicon layer is heavily doped with phosphorus to form a good back contact layer. However, the thickness of the silicon oxide layer is only 1.4-1.8nm, the influence of tunneling effect beyond the range is larger, and the thickness, uniformity and stability fluctuation of the tunneling silicon oxide layer are larger due to the adoption of the low-pressure chemical vapor deposition process under the influence of a quartz boat carrier, oxygen flow, pressure, temperature and the like in the low-pressure chemical vapor deposition process. Therefore, the P-diffusion heavily doped is performed after the polysilicon layer is continuously deposited, and the subsequent P-diffusion doped is easy to cause P to penetrate through the silicon oxide layer into the intrinsic silicon due to the poor thickness, uniformity and stability of the silicon oxide layer, thereby increasing the recombination of the intrinsic silicon and reducing the N formed subsequently + The contact capability of the polysilicon layer causes reduced open-voltage and fill, resulting in lower cell conversion efficiency.
Disclosure of Invention
The application discloses a manufacturing method of an N-TOPCON battery, which aims to solve the problem that the thickness, uniformity and stability of a tunneling silicon oxide layer are poor due to the adoption of an LPCVD (low pressure chemical vapor deposition) process.
In order to achieve the above object, the embodiment of the present specification adopts the following technical solutions:
the manufacturing method of the N-TOPCON battery comprises the following steps:
(A) Boron impurity expansion is carried out on the front surface of the N-type silicon substrate after texturing, and a P+ layer and a borosilicate glass layer are formed on the front surface of the N-type silicon substrate;
(B) Polishing the back surface of the N-type silicon substrate;
(C) Under the oxygen atmosphere, laser treatment is adopted on the back surface of the N-type silicon substrate, a silicon oxide layer is formed on the back surface of the N-type silicon substrate, and then a polysilicon layer is grown on the silicon oxide layer;
(D) Performing phosphorus diffusion on the polysilicon layer on the back surface of the N-type silicon substrate to form an N+ polysilicon layer and a phosphosilicate glass layer;
(E) Removing the borosilicate glass layer on the front side of the N-type silicon substrate, and removing the phosphosilicate glass layer on the back side of the N-type silicon substrate;
(F) Forming an aluminum oxide layer on the front P+ layer of the N-type silicon substrate;
(G) Forming doped silicon layers on the front and back surfaces of the N-type silicon substrate;
(H) Electrodes were prepared to give N-TOPCon cells.
Optionally, the front surface of the N-type silicon substrate after the texturing is subjected to boron impurity expansion in the step (A) by introducing BCl 3 Or BBr 3 The gas undergoes boron impurity expansion.
Optionally, the back surface of the N-type silicon substrate is polished in step (B) by an alkaline cleaning method.
Optionally, the oxygen flow rate in the oxygen atmosphere in the step (C) is 1000-3000sccm.
Optionally, the thickness of the silicon oxide layer in step (C) is 1.5-1.75nm.
Optionally, the thickness of the polysilicon layer in step (C) is 80-130nm.
Optionally, the sheet resistance of the n+ polysilicon layer in the step (D) is 40-50Ω.
Optionally, in the step (E), removing the borosilicate glass layer on the front side of the N-type silicon substrate by adopting an acid washing method, and removing the phosphosilicate glass layer on the back side of the N-type silicon substrate.
Optionally, the thickness of the aluminum oxide layer in step (F) is 3.5-4.5nm.
Optionally, in the step (G), the thickness of the doped silicon layer formed on the front surface of the N-type silicon substrate is 70-72nm, and the thickness of the doped silicon layer formed on the back surface of the N-type silicon substrate is 78-80nm.
The above at least one technical scheme adopted by the embodiment of the application can achieve the following beneficial effects:
according to the application, the passivation and contact technology of the N-TOPCON battery is fully utilized, on the basis of the existing polysilicon structure, the laser heating and the oxidation are used for forming the tunneling silicon oxide layer with stable thickness and compactness on the back surface of the N-type silicon substrate, the surface oxidation treatment can be completed in a short time by the method, the thickness and uniformity of the silicon oxide layer can be controlled, and the polysilicon and P expansion are matched, so that a relatively stable and efficient tunneling and contact structure is obtained, and the efficiency can be stably improved. The application does not use expensive materials or complex process methods, so the application has larger mass production practicability, has obvious effect on improving efficiency and greatly reduces production cost.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:
fig. 1 is a schematic diagram of the structure of the N-TOPCon cell obtained in examples 1-3 of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be clearly and completely described below with reference to specific embodiments of the present application and corresponding drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
According to one embodiment of the present application, there is provided a method for manufacturing an N-TOPCon battery, comprising the steps of:
(1) Boron impurity expansion is carried out on the front surface of the N-type silicon substrate after texturing, and a P+ layer and a borosilicate glass layer are formed on the front surface of the N-type silicon substrate;
(2) Polishing the back surface of the N-type silicon substrate;
(3) Under the oxygen atmosphere, laser treatment is adopted on the back surface of the N-type silicon substrate, a silicon oxide layer is formed on the back surface of the N-type silicon substrate, and then a polysilicon layer is grown on the silicon oxide layer;
(4) Performing phosphorus diffusion on the polysilicon layer on the back surface of the N-type silicon substrate to form an N+ polysilicon layer and a phosphosilicate glass layer;
(5) Removing the borosilicate glass layer on the front side of the N-type silicon substrate, and removing the phosphosilicate glass layer on the back side of the N-type silicon substrate;
(6) Forming an aluminum oxide layer on the front P+ layer of the N-type silicon substrate;
(7) Forming doped silicon layers on the front and back surfaces of the N-type silicon substrate;
(8) Electrodes were prepared to give N-TOPCon cells.
In the embodiment of the present disclosure, the N-type silicon substrate after the texturing in the step (1) is a nano-sized textured surface formed on the front and back surfaces of the N-type silicon substrate by texturing the N-type silicon substrate, which has an anti-reflection effect. In the step (1), any boron source can be adopted to carry out boron impurity expansion on the front surface of the N-type silicon substrate after the texturing, and the application is not limited to the boron impurity expansion. Alternatively, by passing through BCl 3 Or BBr 3 The gas undergoes boron impurity expansion.
And (2) when the P+ layer and the borosilicate glass layer are formed on the front surface of the N-type silicon substrate, the borosilicate glass layer is formed on the back surface of the N-type silicon substrate. When boron impurity expansion is carried out on the front surface of the N-type silicon substrate after the texturing, BCl3 or BBr3 gas is introduced in the doping process, so that a P+ layer is formed, and a borosilicate glass layer is formed on the surface of the P+ layer. And forming a borosilicate glass layer around the back surface plated on the N-type silicon substrate while forming the borosilicate glass layer on the front surface of the N-type silicon substrate. In the embodiment of the present disclosure, in the step (2), the borosilicate glass layer on the back surface of the N-type silicon substrate is removed and polished. Any method may be used in the embodiments of the present disclosure to remove the borosilicate glass layer on the back side of the N-type silicon substrate, which is not limited in this disclosure. Optionally, removing the borosilicate glass layer on the back surface of the N-type silicon substrate by adopting an acid washing method, wherein the acid can be hydrofluoric acid.
In the embodiment of the present disclosure, the back surface of the N-type silicon substrate may be polished in step (2) by any method, which is not limited in the present disclosure, so as to ensure that a flat surface structure can be formed on the back surface of the N-type silicon substrate. Optionally, the back surface of the N-type silicon substrate is polished by an alkali washing method, wherein the alkali can be sodium hydroxide alkali liquor.
In the embodiment of the present specification, the laser oxidation is to heat the surface of the N-type silicon substrate by using a laser beam to reach the oxidation temperature, and then perform the oxidation reaction in an oxygen atmosphere to form the silicon oxide layer. The method can complete surface oxidation treatment in a short time, and can control the thickness and uniformity of a silicon oxide layer, which can also be called a tunneling silicon oxide layer, so as to improve the performance of the surface of an N-type silicon substrate.
In the embodiment of the present disclosure, the flow rate of oxygen in the oxygen atmosphere in the step (3) is 1000-3000sccm, and under this flow rate, the amount of oxygen introduced can be stabilized, so that the oxidation reaction proceeds smoothly. Alternatively, the oxygen flow rate in the oxygen atmosphere may be 1000sccm, 1200sccm, 1400sccm, 1600sccm, 1800sccm, 2000sccm, 2200sccm, 2400sccm, 2600sccm, 2800sccm, 3000sccm, or any value therebetween.
In the embodiment of the present disclosure, the thickness of the silicon oxide layer in the step (3) is 1.5-1.75nm, and the silicon oxide layer is limited in this thickness range, which can better ensure tunneling and passivation of the N-TOPCon battery. Alternatively, the thickness of the silicon oxide layer may be 1.5nm, 1.55nm, 1.6nm, 1.65nm, 1.7nm, 1.75nm, or any value therebetween.
In the embodiment of the present disclosure, the thickness of the polysilicon layer in the step (3) is 80-130nm, and the polysilicon layer is limited to the thickness range, and N is formed subsequently + Polysilicon layer capable of preventing N penetration of metal paste for forming silver electrode + The polysilicon layer causes problems of intrinsic silicon recombination and low open-pressure. Alternatively, the thickness of the polysilicon layer may be 80nm, 85nm, 90nm, 95nm, 100nm, 105nm, 110nm, 115nm, 120nm, 125nm, 130nm, or any value therebetween.
In the embodiment of the specification, the laser treatment is performed on the whole area of the back surface of the N-type silicon substrate, so that the process precision requirement is not so high, and the process flow is simple compared with the process flow of the partial area treatment on the back surface of the N-type silicon substrate.
And (3) forming a polysilicon layer on the borosilicate glass layer on the front surface of the N-type silicon substrate. When the polysilicon layer is formed by a Low Pressure Chemical Vapor Deposition (LPCVD) method, the polysilicon layer is formed around the front side plated to the N-type silicon substrate while the polysilicon layer is formed on the back side of the N-type silicon substrate. When the polysilicon layer is formed by a Plasma Enhanced Chemical Vapor Deposition (PECVD) method, the polysilicon layer is not formed on the borosilicate glass layer on the front side of the N-type silicon substrate. When N-type silicon baseWhen the polysilicon layer is formed on the borosilicate glass layer on the front surface of the substrate, the step (4) is to form N on the front surface of the N-type silicon substrate when phosphorus diffusion is carried out on the polysilicon layer on the back surface of the N-type silicon substrate + A polysilicon layer and a phosphosilicate glass layer. At the same time, in the step (5), N on the front surface of the N-type silicon substrate is required + And removing the polysilicon layer and the phosphosilicate glass layer. In the embodiment of the present disclosure, any method may be used to remove N on the front surface of the N-type silicon substrate + A polysilicon layer and a phosphosilicate glass layer, to which the present application is not limited. Optionally, the phosphosilicate glass layer on the front side of the N-type silicon substrate is removed by an acid washing method, and the n+ polysilicon layer on the front side of the N-type silicon substrate is removed by an alkali washing method, which is a common method in the field. Specifically, the alkaline washing method can adopt sodium hydroxide alkaline washing, the acid washing method can adopt hydrofluoric acid washing, firstly, a roller running chain type acid washing method is adopted to remove the phosphosilicate glass layer on the front side of the N-type silicon substrate, then a groove type alkaline washing method is adopted to remove the N+ polysilicon layer on the front side of the N-type silicon substrate, finally, the borosilicate glass layer on the front side of the N-type silicon substrate is removed, and the phosphosilicate glass layer on the back side of the N-type silicon substrate is removed.
The purpose of phosphorus diffusion in the step (4) is to dope and deposit phosphorus on the polysilicon layer on the back surface of the N-type silicon substrate to form an N+ polysilicon layer, and the doping and the phosphorus deposition are realized by introducing oxygen and a phosphorus source, so that a phosphosilicate glass layer can be formed on the surface of the N+ polysilicon layer, the phosphorus diffusion process is carried out at high temperature, phosphorus in the phosphosilicate glass layer can promote to form the N+ polysilicon layer, and the phosphosilicate glass layer still remains on the surface of the N+ polysilicon layer.
In the embodiment of the present disclosure, the sheet resistance of the n+ polysilicon layer in the step (4) is 40-50Ω, and the sheet resistance of the n+ polysilicon layer is limited within this numerical range, so that the problem that the n+ polysilicon layer is burned through by the metal paste for forming the silver electrode later, which causes intrinsic silicon recombination and low open-circuit voltage can be prevented. Alternatively, the sheet resistance of the n+ polysilicon layer may be 40Ω, 41Ω, 42Ω, 43Ω, 44Ω, 45Ω, 46 Ω, 47 Ω, 48Ω, 49Ω, 50Ω, or any value therebetween.
In the embodiment of the present disclosure, in step (5), any method may be used to remove the borosilicate glass layer on the front side of the N-type silicon substrate and remove the phosphosilicate glass layer on the back side of the N-type silicon substrate, which is not limited in the present disclosure. Optionally, an acid washing method is used to remove the borosilicate glass layer on the front side of the N-type silicon substrate and the phosphosilicate glass layer on the back side of the N-type silicon substrate, and the acid washing method is also a common method for removing the borosilicate glass layer and the phosphosilicate glass layer in the field, and the removal can be performed synchronously or stepwise. Specifically, the pickling method can adopt hydrofluoric acid pickling and a groove type HF pickling method for removal.
In the embodiment of the present disclosure, in step (6), an optional method may be used to form an aluminum oxide layer on the p+ layer on the front surface of the N-type silicon substrate, which is not limited in the present disclosure. Optionally introducing water/TMA/N on the P+ layer on the front surface of the N-type silicon substrate at 270-300deg.C under vacuum 2 Deposition of Al using ALD 2 O 3 An aluminum oxide layer is formed to a thickness of 3.5-4.5nm, where ALD is atomic layer deposition Atom Layer Deposition and TMA is trimethylaluminum.
In the embodiment of the present disclosure, in step (7), a doped silicon layer may be formed on the front surface of the N-type silicon substrate by any method, which is not limited in the present disclosure, and the thickness is 70-72nm. Alternatively, the doped silicon layer may be a SiN layer, a SiON layer, or a SiN, siON mixed layer. Specifically, NH is introduced under vacuum 3 、SiH 4 A SiN layer with the thickness of 70-72nm can be formed on the aluminum oxide layer on the front surface of the N-type silicon substrate by PECVD deposition; or introducing NH under vacuum 3 、N 2 O、SiH 4 Forming a SiON layer with the thickness of 70-72nm on the aluminum oxide layer on the front surface of the N-type silicon substrate by PECVD deposition; or introducing NH under vacuum 3 、N 2 O、SiH 4 And forming a SiN and SiON mixed layer with the thickness of 70-72nm on the aluminum oxide layer on the front surface of the N-type silicon substrate by PECVD deposition. Wherein PECVD is plasma enhanced chemical vapor deposition Plasma Enhanced Chemical Vapor Deposition.
In the embodiment of the present disclosure, in step (7), the doped silicon layer may be formed on the back surface of the N-type silicon substrate by any method, which is not limited in the present disclosure, and has a thickness of 78-80nm. Alternatively, the doped silicon layer may be a SiN layer, a SiON layer, or a SiN, siON mixed layer. Specifically, NH is introduced under vacuum 3 、SiH 4 Forming a SiN layer with the thickness of 78-80nm on the N+ polycrystalline silicon layer on the back surface of the N-type silicon substrate by PECVD deposition; or introducing NH under vacuum 3 、N 2 O、SiH 4 Forming a SiON layer with the thickness of 78-80nm on the N+ polycrystalline silicon layer on the back surface of the N-type silicon substrate by PECVD deposition; or introducing NH under vacuum 3 、N 2 O、SiH 4 And forming a SiN and SiON mixed layer with the thickness of 78-80nm on the N+ polycrystalline silicon layer on the back surface of the N-type silicon substrate by PECVD deposition.
In the examples herein, the electrode may be prepared in step (8) by any method to obtain an N-TOPCon battery, which is not limited in the present application. Optionally, electrode printing is performed on the front side and the back side of the N-type silicon substrate, sintering and light attenuation are performed to form a silver electrode, and the N-TOPCO battery is obtained, wherein the silver electrode is positioned on the P+ layer, the aluminum oxide layer and the doped silicon layer on the front side of the N-type silicon substrate, and the silver electrode is positioned on the N+ polycrystalline silicon layer and the doped silicon layer on the back side of the N-type silicon substrate.
The following describes in detail the technical solutions provided by the embodiments of the present application with reference to the accompanying drawings.
Example 1:
the manufacturing method of the N-TOPCON battery comprises the following steps:
(1) The N-type silicon substrate is subjected to texturing, and nanoscale textured surfaces are formed on the front surface and the back surface of the N-type silicon substrate;
(2) Introducing BCl 3 Boron diffusion doping is carried out on the front side of the N-type silicon substrate after texturing by gas, a doped P+ layer and a borosilicate glass layer are formed on the front side of the N-type silicon substrate, and a borosilicate glass layer is formed on the back side of the N-type silicon substrate;
(3) Removing the borosilicate glass layer on the back surface of the N-type silicon substrate by hydrofluoric acid pickling, and performing caustic washing and polishing on the back surface of the N-type silicon substrate by sodium hydroxide solution to form a flat surface structure;
(4) Under the oxygen atmosphere with the oxygen flow of 2000sccm, carrying out laser treatment on the whole back surface of the N-type silicon substrate, forming a silicon oxide layer with the thickness of 1.6nm on the whole back surface of the N-type silicon substrate, growing on the silicon oxide layer to form a polysilicon layer with the thickness of 110nm, and forming a polysilicon layer on a borosilicate glass layer on the front surface of the N-type silicon substrate;
(5) Performing phosphorus diffusion on the polysilicon layer on the back surface of the N-type silicon substrate to form an N+ polysilicon layer and a phosphosilicate glass layer, wherein the sheet resistance of the N+ polysilicon layer is 45Ω, and simultaneously, the N+ polysilicon layer and the phosphosilicate glass layer are formed on the front surface of the N-type silicon substrate;
(6) Firstly removing a phosphorosilicate glass layer on the front side of an N-type silicon substrate by adopting a roller running chain type hydrofluoric acid pickling method, then removing an N+ polysilicon layer on the front side of the N-type silicon substrate by adopting a groove type sodium hydroxide solution alkaline cleaning method, and finally removing a borosilicate glass layer on the front side of the N-type silicon substrate and a phosphorosilicate glass layer on the back side of the N-type silicon substrate by adopting a groove type hydrofluoric acid pickling method;
(7) On the P+ layer on the front side of the N-type silicon substrate, under the vacuum 300 ℃, water/TMA/N is introduced 2 Depositing aluminum oxide by ALD to form an aluminum oxide layer with the thickness of 4 nm;
(8) NH is introduced into the aluminum oxide layer on the front side of the N-type silicon substrate under vacuum 3 、SiH 4 Forming a SiN layer with the thickness of 72nm by PECVD deposition;
(9) NH is introduced into the N+ polysilicon layer on the back of the N-type silicon substrate under vacuum 3 、SiH 4 Depositing by PECVD to form a SiN layer with the thickness of 80 nm;
(10) And (3) electrode printing is carried out on the front surface and the back surface of the N-type silicon substrate, then sintering and light attenuation are carried out, and a silver electrode is formed, so that the N-TOPCO battery is obtained, and the specific structure of the N-TOPCO battery is shown in figure 1.
Compared with the existing method of forming the silicon oxide layer by thermal oxidation in the modes of LPCVD and the like, the method provided by the embodiment of the application has the advantages that the whole surface of the back surface of the N-type silicon substrate is subjected to high-temperature oxidation treatment by laser under the oxygen atmosphere, the compactness and uniformity of the obtained tunneling silicon oxide layer are excellent, and the thickness discrete range of the whole surface silicon oxide layer on the back surface of the N-type silicon substrate is narrower than that of a production line.
In the method for manufacturing the N-TOPCON battery of the embodiment, a stable and compact tunneling silicon oxide layer is deposited on the whole surface of the back surface of an N-type silicon substrate in a laser oxidation mode, and then a polycrystalline silicon layer is deposited to be matched with heavily doped P. Because the compactness and uniformity are effectively increased by laser oxidation, under heavily doped P, the tunneling silicon oxide layer effectively maintains the high doping capability of polysilicon, and simultaneously reduces the capability of P for internally expanding intrinsic silicon, so that a stable high-contact low-internal-expansion composite back structure is formed, the passivation capability of the back is improved, and meanwhile, the contact capability is improved, thereby improving the efficiency.
Example 2:
the manufacturing method of the N-TOPCON battery comprises the following steps:
(1) The N-type silicon substrate is subjected to texturing, and nanoscale textured surfaces are formed on the front surface and the back surface of the N-type silicon substrate;
(2) Pass through BBr 3 Boron diffusion doping is carried out on the front side of the N-type silicon substrate after texturing by gas, and a doped P+ layer and a borosilicate glass layer are formed on the front side of the N-type silicon substrate;
(3) Performing caustic washing and polishing on the back of the N-type silicon substrate by using sodium hydroxide solution to form a flat surface structure;
(4) Under the oxygen atmosphere with the oxygen flow of 1000sccm, carrying out laser treatment on the whole back surface of the N-type silicon substrate, forming a silicon oxide layer with the thickness of 1.5nm on the whole back surface of the N-type silicon substrate, and then growing on the silicon oxide layer to form a polysilicon layer with the thickness of 80 nm;
(5) Performing phosphorus diffusion on the polysilicon layer on the back surface of the N-type silicon substrate to form an N+ polysilicon layer and a phosphosilicate glass layer, wherein the sheet resistance of the N+ polysilicon layer is 40Ω;
(6) Removing the borosilicate glass layer on the front side of the N-type silicon substrate and the phosphosilicate glass layer on the back side of the N-type silicon substrate by adopting a groove type hydrofluoric acid pickling method;
(7) On the P+ layer on the front side of the N-type silicon substrate, under the vacuum of 270 ℃, water/TMA/N is introduced 2 Depositing aluminum oxide by ALD to form an aluminum oxide layer with the thickness of 3.5 nm;
(8) NH is introduced into the aluminum oxide layer on the front side of the N-type silicon substrate under vacuum 3 、SiH 4 Forming a SiN layer with the thickness of 70nm by PECVD deposition;
(9) NH is introduced into the N+ polysilicon layer on the back of the N-type silicon substrate under vacuum 3 、SiH 4 Forming a SiN layer with the thickness of 78nm by PECVD deposition;
(10) And (3) electrode printing is carried out on the front surface and the back surface of the N-type silicon substrate, then sintering and light attenuation are carried out, and a silver electrode is formed, so that the N-TOPCO battery is obtained, and the specific structure of the N-TOPCO battery is shown in figure 1.
Example 3:
the manufacturing method of the N-TOPCON battery comprises the following steps:
(1) The N-type silicon substrate is subjected to texturing, and nanoscale textured surfaces are formed on the front surface and the back surface of the N-type silicon substrate;
(2) Introducing BCl 3 Boron diffusion doping is carried out on the front side of the N-type silicon substrate after texturing by gas, and a doped P+ layer and a borosilicate glass layer are formed on the front side of the N-type silicon substrate;
(3) Performing alkaline washing and polishing on the back surface of the N-type silicon substrate by using a sodium hydroxide solution to form a flat surface structure;
(4) Under the oxygen atmosphere with the oxygen flow of 3000sccm, carrying out laser treatment on the whole back surface of the N-type silicon substrate, forming a silicon oxide layer with the thickness of 1.75nm on the whole back surface of the N-type silicon substrate, and then growing on the silicon oxide layer to form a polysilicon layer with the thickness of 130 nm;
(5) Performing phosphorus diffusion on the polysilicon layer on the back surface of the N-type silicon substrate to form an N+ polysilicon layer and a phosphosilicate glass layer, wherein the sheet resistance of the N+ polysilicon layer is 50Ω;
(6) Removing the borosilicate glass layer on the front side of the N-type silicon substrate and the phosphosilicate glass layer on the back side of the N-type silicon substrate by adopting a groove type hydrofluoric acid pickling method;
(7) On the P+ layer on the front side of the N-type silicon substrate, under the vacuum of 280 ℃, water/TMA/N is introduced 2 Depositing aluminum oxide by ALD to form an aluminum oxide layer with the thickness of 4.5 nm;
(8) NH is introduced into the aluminum oxide layer on the front side of the N-type silicon substrate under vacuum 3 、N 2 O、SiH 4 Forming a SiON layer with the thickness of 71nm by PECVD deposition;
(9) NH is introduced into the N+ polysilicon layer on the back of the N-type silicon substrate under vacuum 3 、N 2 O、SiH 4 Is good forDepositing by PECVD to form a SiON layer with the thickness of 79 nm;
(10) And (3) electrode printing is carried out on the front surface and the back surface of the N-type silicon substrate, then sintering and light attenuation are carried out, and a silver electrode is formed, so that the N-TOPCO battery is obtained, and the specific structure of the N-TOPCO battery is shown in figure 1.
Comparative example 1:
the manufacturing method of the N-TOPCON battery comprises the following steps:
(1) The N-type silicon substrate is subjected to texturing, and nanoscale textured surfaces are formed on the front surface and the back surface of the N-type silicon substrate;
(2) Introducing BCl 3 Boron diffusion doping is carried out on the front side of the N-type silicon substrate after texturing by gas, a doped P+ layer and a borosilicate glass layer are formed on the front side of the N-type silicon substrate, and a borosilicate glass layer is formed on the back side of the N-type silicon substrate;
(3) Removing the borosilicate glass layer on the back surface of the N-type silicon substrate by hydrofluoric acid pickling, and performing caustic washing and polishing on the back surface of the N-type silicon substrate by sodium hydroxide solution to form a flat surface structure;
(4) LPCVD treatment is adopted on the back surface of the N-type silicon substrate at the high temperature and the normal pressure of 600 ℃, a silicon oxide layer with the thickness of 1.6nm is firstly formed on the back surface of the N-type silicon substrate, then a polysilicon layer with the thickness of 100nm is grown on the silicon oxide layer, and meanwhile, a polysilicon layer is formed on a borosilicate glass layer on the front surface of the N-type silicon substrate;
(5) Performing phosphorus diffusion on the polysilicon layer on the back surface of the N-type silicon substrate to form an N+ polysilicon layer and a phosphosilicate glass layer, wherein the sheet resistance of the N+ polysilicon layer is 45Ω, and simultaneously, the N+ polysilicon layer and the phosphosilicate glass layer are formed on the front surface of the N-type silicon substrate;
(6) Firstly removing a phosphorosilicate glass layer on the front side of an N-type silicon substrate by adopting a roller running chain type hydrofluoric acid pickling method, then removing an N+ polysilicon layer on the front side of the N-type silicon substrate by adopting a groove type sodium hydroxide solution alkaline cleaning method, and finally removing a borosilicate glass layer on the front side of the N-type silicon substrate and a phosphorosilicate glass layer on the back side of the N-type silicon substrate by adopting a groove type hydrofluoric acid pickling method;
(7) On the P+ layer on the front side of the N-type silicon substrate, under the vacuum 300 ℃, water/TMA/N is introduced 2 Deposition of aluminum oxide using ALD to a thickness of 4nmIs a layer of aluminum oxide;
(8) NH is introduced into the aluminum oxide layer on the front side of the N-type silicon substrate under vacuum 3 、SiH 4 Forming a SiN layer with the thickness of 72nm by PECVD deposition;
(9) NH is introduced into the N+ polysilicon layer on the back of the N-type silicon substrate under vacuum 3 、SiH 4 Depositing by PECVD to form a SiN layer with the thickness of 80 nm;
(10) And (3) electrode printing is carried out on the front surface and the back surface of the N-type silicon substrate, then sintering and light attenuation are carried out, and a silver electrode is formed, so that the N-TOPCO battery is obtained.
Performance test:
the N-TOPCon batteries of example 1, example 2, example 3 and comparative example 1 were selected for performance testing, and the test results are shown in the following table.
Taking the example 1 of the application as an example, the uniformity of the tunneling silicon oxide layer is 0.6% better than that of the comparative example 1 through the spectroscopic ellipsometer test; the conversion efficiency (eta) of the N-TOPCon cell obtained by the IV tester was 0.09% higher than that of the N-TOPCon cell obtained in comparative example 1, specifically, the open pressure (uoc) was 1.5mV higher, the short flow (isc) was substantially flat, the rs (string resistance) was decreased by 0.03mΩ, and the filling (ff) was increased by 0.1%. Therefore, the N-TOPCon battery obtained by the preparation method increases tunneling compactness, ensures contact property due to high doping concentration of polysilicon, improves filling ff value, reduces the risk of inward expansion of an N-type silicon substrate, improves opening pressure uoc value, accords with mechanism, and improves performance to meet expectations.
The N-TOPCO battery provided by the application has the advantages that the laser heating and the oxidation are used for forming the tunneling silicon oxide layer with stable thickness and compactness on the back surface of the N-type silicon substrate, the surface oxidation treatment can be completed in a short time by the method, the thickness and uniformity of the silicon oxide layer can be controlled, and the polysilicon and the P diffusion are matched, so that a relatively stable and efficient tunneling and contact structure is obtained, and the efficiency can be stably improved.
The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and variations of the present application will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the application are to be included in the scope of the claims of the present application.
Claims (10)
1. The manufacturing method of the N-TOPCON battery is characterized by comprising the following steps of:
(A) Boron impurity expansion is carried out on the front surface of the N-type silicon substrate after texturing, and a P+ layer and a borosilicate glass layer are formed on the front surface of the N-type silicon substrate;
(B) Polishing the back surface of the N-type silicon substrate;
(C) Under the oxygen atmosphere, laser treatment is adopted on the back surface of the N-type silicon substrate, a silicon oxide layer is formed on the back surface of the N-type silicon substrate, and then a polysilicon layer is grown on the silicon oxide layer;
(D) Performing phosphorus diffusion on the polysilicon layer on the back surface of the N-type silicon substrate to form an N+ polysilicon layer and a phosphosilicate glass layer;
(E) Removing the borosilicate glass layer on the front side of the N-type silicon substrate, and removing the phosphosilicate glass layer on the back side of the N-type silicon substrate;
(F) Forming an aluminum oxide layer on the front P+ layer of the N-type silicon substrate;
(G) Forming doped silicon layers on the front and back surfaces of the N-type silicon substrate;
(H) And preparing an electrode to obtain the N-TOPCO battery.
2. The method of claim 1, wherein the boron doping of the front surface of the textured N-type silicon substrate in step (A) is performed by introducing BCl 3 Or BBr 3 The gas undergoes boron impurity expansion.
3. The method of claim 1, wherein the back surface of the N-type silicon substrate is polished in step (B) by an alkaline cleaning method.
4. The method according to claim 1, wherein the oxygen flow rate in the oxygen atmosphere in the step (C) is 1000-3000sccm.
5. The method of claim 1, wherein the thickness of the silicon oxide layer in step (C) is 1.5-1.75nm.
6. The method of claim 1, wherein the thickness of the polysilicon layer in step (C) is 80-130nm.
7. The method of claim 1, wherein the n+ polysilicon layer in step (D) has a sheet resistance of 40-50Ω.
8. The method of claim 1, wherein in step (E), an acid washing method is used to remove the borosilicate glass layer on the front side of the N-type silicon substrate, and to remove the phosphosilicate glass layer on the back side of the N-type silicon substrate.
9. The method of claim 1, wherein the thickness of the aluminum oxide layer in step (F) is 3.5-4.5nm.
10. The method of claim 1, wherein the N-type silicon substrate in step (G) has a front side with a doped silicon layer having a thickness of 70-72nm and a back side with a doped silicon layer having a thickness of 78-80nm.
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