CN220731539U - Layered aluminum oxide passivation film and crystalline silicon solar cell prepared based on same - Google Patents
Layered aluminum oxide passivation film and crystalline silicon solar cell prepared based on same Download PDFInfo
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- CN220731539U CN220731539U CN202321843440.4U CN202321843440U CN220731539U CN 220731539 U CN220731539 U CN 220731539U CN 202321843440 U CN202321843440 U CN 202321843440U CN 220731539 U CN220731539 U CN 220731539U
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- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 title claims abstract description 69
- 238000002161 passivation Methods 0.000 title claims abstract description 68
- 229910021419 crystalline silicon Inorganic materials 0.000 title claims abstract description 25
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 97
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 76
- 239000001301 oxygen Substances 0.000 claims abstract description 62
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 56
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 54
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 53
- 239000010703 silicon Substances 0.000 claims abstract description 53
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 44
- 239000000758 substrate Substances 0.000 claims abstract description 43
- 229910052814 silicon oxide Inorganic materials 0.000 claims abstract description 40
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims description 19
- 229920005591 polysilicon Polymers 0.000 claims description 9
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 8
- 229910052796 boron Inorganic materials 0.000 claims description 8
- 229910052751 metal Inorganic materials 0.000 claims description 8
- 239000002184 metal Substances 0.000 claims description 8
- 230000005641 tunneling Effects 0.000 claims description 7
- 229910021421 monocrystalline silicon Inorganic materials 0.000 claims description 4
- 101100409194 Rattus norvegicus Ppargc1b gene Proteins 0.000 claims description 3
- 238000000034 method Methods 0.000 abstract description 33
- 238000000151 deposition Methods 0.000 abstract description 31
- 238000005273 aeration Methods 0.000 abstract description 25
- 238000006243 chemical reaction Methods 0.000 abstract description 12
- 238000002360 preparation method Methods 0.000 abstract description 8
- 239000000969 carrier Substances 0.000 abstract description 2
- 238000000605 extraction Methods 0.000 abstract description 2
- 238000009423 ventilation Methods 0.000 abstract description 2
- 239000010410 layer Substances 0.000 description 178
- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 description 18
- 230000003647 oxidation Effects 0.000 description 17
- 238000007254 oxidation reaction Methods 0.000 description 17
- 230000008021 deposition Effects 0.000 description 16
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 15
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 12
- 229910017604 nitric acid Inorganic materials 0.000 description 12
- 239000007789 gas Substances 0.000 description 11
- 238000000231 atomic layer deposition Methods 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- 238000009792 diffusion process Methods 0.000 description 9
- 229910004298 SiO 2 Inorganic materials 0.000 description 8
- ILAHWRKJUDSMFH-UHFFFAOYSA-N boron tribromide Chemical compound BrB(Br)Br ILAHWRKJUDSMFH-UHFFFAOYSA-N 0.000 description 8
- 239000002356 single layer Substances 0.000 description 8
- 238000000137 annealing Methods 0.000 description 7
- 229910014299 N-Si Inorganic materials 0.000 description 4
- 238000000026 X-ray photoelectron spectrum Methods 0.000 description 4
- 239000002253 acid Substances 0.000 description 4
- 230000032798 delamination Effects 0.000 description 4
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 3
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 3
- 230000002950 deficient Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000010306 acid treatment Methods 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 230000006798 recombination Effects 0.000 description 2
- 238000005215 recombination Methods 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- AFCARXCZXQIEQB-UHFFFAOYSA-N N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CCNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 AFCARXCZXQIEQB-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000003667 anti-reflective effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000006388 chemical passivation reaction Methods 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 238000004518 low pressure chemical vapour deposition Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 125000004437 phosphorous atom Chemical group 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000004151 rapid thermal annealing Methods 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- -1 silver-aluminum Chemical compound 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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- Formation Of Insulating Films (AREA)
Abstract
The utility model provides a layered aluminum oxide passivation film and a crystalline silicon solar cell prepared based on the same. The structure of the layered alumina passivation film sequentially comprises a silicon substrate, a silicon oxide layer, an under-oxidized alumina layer and an oxygen-enriched alumina layer from bottom to top; the under-oxygen alumina layer and the oxygen-rich alumina layer are prepared by controlling H in the process of preparing alumina 2 O or O 3 Is obtained by the aeration time of (1) when preparing an under-oxidized aluminum oxide layer H 2 O or O 3 Is less than H in the preparation of an oxygen-enriched alumina layer 2 O or O 3 Is used for the ventilation time of the air bag. The utility model realizes the aluminaThe gradient field passivation of the silicon solar cell can enhance the extraction of majority carriers and improve the conversion efficiency of the silicon solar cell; in addition, the utility model does not need to increase the cost, and the method for depositing the alumina is changed on the basis of the existing mature process.
Description
Technical Field
The utility model relates to the technical field of solar cells, in particular to a layered aluminum oxide passivation film and a crystalline silicon solar cell prepared based on the layered aluminum oxide passivation film.
Background
In the field of photovoltaic cells, the production cost of the crystalline silicon solar cell is reduced, and the conversion efficiency of the crystalline silicon solar cell is further improved, so that the method is still a pursued goal. In the whole battery structure, because of the disordered arrangement of silicon atoms, a large number of dangling bonds exist on the surface of the silicon wafer, electrons are easily captured by the dangling bonds, the surface recombination of the battery is increased, and the battery efficiency is reduced. In order to improve the efficiency of crystalline silicon solar cells and reduce surface recombination, a layer of very thin dielectric or semiconductor material is typically deposited on the device surface, i.e., surface passivation. Alumina, an oxide having semiconducting properties, has a chemical passivation effect on the silicon surface. In addition, due to the existence of aluminum vacancies in the aluminum oxide, the aluminum oxide presents electronegativity, and the deposited P-type emitter side of the crystalline silicon solar cell presents field passivation effect. At present, the aluminum oxide film is widely applied to P-type perc batteries and N-type TOPCO batteries.
Disclosure of Invention
The utility model aims to provide a layered aluminum oxide passivation film and a crystalline silicon solar cell prepared based on the layered aluminum oxide passivation film, so as to realize gradient field passivation of aluminum oxide and improve the conversion efficiency of the crystalline silicon solar cell.
The utility model is realized in the following way:
a layered alumina passivation film comprises a silicon substrate, a silicon oxide layer, an under-oxidized alumina layer and an oxygen-enriched alumina layer from bottom to top in sequence; the silicon substrate is P-type monocrystalline silicon, P-type polycrystalline silicon or N-type monocrystalline silicon or N-type polycrystalline silicon after boron doping.
The utility model deposits an under-oxygen alumina film on one side of a P-type emitter of a crystalline silicon substrate with a silicon oxide layer, and then deposits an oxygen-rich alumina film by changing a growth process, wherein the growth temperature of the alumina film is 250 ℃. Then high-temperature annealing is carried out to form layered Al in the form of under-oxidized aluminum oxide/rich-oxidized aluminum oxide 2 O 3 And (3) a passivation film.
Specific: the crystalline silicon substrate is P-type single/polycrystalline silicon or N-type single/polycrystalline silicon which forms PN junction after boron doping, and the resistivity is 0.1-10 omega cm.
The silicon oxide layer is generated on the surface of the crystalline silicon substrate by adopting a high-temperature thermal oxidation method or a wet chemical oxidation method, the thickness of the silicon oxide layer is 0.5 nm-3 nm, and the thickness of the silicon oxide layer is preferably 1-2 nm.
The layered alumina passivation film in the form of under-oxidized alumina/rich-oxidized alumina has a structure of two or more layers, namely: for oxygen gradient alumina structures formed due to different oxygen contents in alumina, a two-layer gradient structure or a three-layer or more gradient structure is adopted, and the layered alumina passivation film is obtained by adopting an ALD (atomic layer deposition) but is not limited to an ALD deposition method. ALD process using trimethylaluminum and H 2 O gas or trimethylaluminum and O 3 The gas, the process temperature is 250 ℃, and the layered alumina in the form of the underoxidized alumina/the enriched oxidized alumina adopts different H 2 O or O 3 The aeration time method is obtained. During the deposition of the under-oxidized alumina, H in one alumina growth cycle 2 O or O 3 The aeration time of (2) is 1-5 seconds, the optimal aeration time is 3 seconds, the aeration time of trimethylaluminum is 1-10 seconds, and the optimal aeration time is 5 seconds. In the deposition of oxygen-enriched alumina, H in one alumina growth cycle 2 O or O 3 The aeration time of (2) is 6-10 seconds, the optimal aeration time is 6 seconds, the aeration time of trimethylaluminum is 1-10 seconds, and the optimal aeration time is 5 seconds. H during the preparation of the under-oxidized aluminum oxide in an aluminum oxide growth cycle 2 O orO 3 Is less in aeration time than H in the preparation of oxygen-enriched alumina 2 O or O 3 Is used for the ventilation time of the air bag. The thickness of the prepared under-oxygen alumina and the thickness of the prepared rich-oxygen alumina are both 0.5-5nm.
High-temperature annealing is needed after aluminum oxide deposition, and the high-temperature annealing is carried out in a fast heating tube furnace at 300-650 ℃ for 10-120 min.
The utility model provides a layered aluminum oxide passivation film and a crystalline silicon solar cell prepared based on the same. By controlling the growth process of alumina, firstly depositing an oxygen-deficient alumina film and then depositing an oxygen-enriched alumina film. For example, ALD deposition methods can be used to form a layered Al of suboxyalumina/oxyalumina-rich 2 O 3 And the passivation film is used for realizing gradient field passivation of aluminum oxide and improving the conversion efficiency of the crystalline silicon solar cell.
The layered alumina passivation film provided by the utility model can be applied to a P-type perc battery or an N-type TOPCON battery.
Specifically, the structure of the N-type TOPCON cell comprises an N-type silicon substrate, wherein a P+ doped layer, a silicon oxide layer, an under-oxidized aluminum oxide layer, an oxygen-enriched aluminum oxide layer and a first SiN layer are sequentially arranged on the front surface of the N-type silicon substrate x A tunneling oxide layer, an N+ doped polysilicon layer and a second SiN layer are sequentially arranged on the back surface of the N-type silicon substrate x Layer, second metal electrode.
The utility model has the technical advantages that: (1) The gradient field passivation of the alumina is realized, the extraction of majority carriers can be enhanced, and the conversion efficiency of the crystalline silicon solar cell is improved. (2) The method does not need to increase the cost, and can change the alumina deposition process method based on the existing mature process.
Drawings
Fig. 1 is a schematic structural view of a layered alumina passivation film provided in example 1 of the present utility model.
Fig. 2 is an XPS spectrum of an alumina rich layer of a layered alumina passivation film structure in example 1 of the present utility model.
Fig. 3 is an XPS spectrum of an under-oxidized aluminum oxide layer of a layered aluminum oxide passivation film structure in example 1 of the present utility model.
Fig. 4 is a schematic structural view of a layered alumina passivation film provided in example 2 of the present utility model.
Fig. 5 is a schematic structural diagram of a device with a double-sided symmetrical passivation structure according to embodiment 3 of the present utility model.
Fig. 6 is a schematic structural view of a double-sided symmetrical passivation structure device provided in comparative example 1 of the present utility model.
Fig. 7 is a graph comparing the iVoc test results of the double-sided symmetrical passivation structure devices obtained in example 3 and comparative example 1 of the present utility model.
Fig. 8 is a schematic structural diagram of a crystalline silicon solar cell according to embodiment 4 of the present utility model.
In the figure: 1. an oxygen-enriched alumina layer; 2. an under-oxidized aluminum oxide layer; 3. a silicon oxide layer; 4. a P-type silicon substrate; 5. a P+ doped layer; 6. an N-type silicon substrate; 7. a first p+ doped layer; 8. a first silicon oxide layer; 9. a first under-oxidized aluminum oxide layer; 10. a first oxygen-enriched alumina layer; 11. first SiN x A layer; 12. a second p+ doped layer; 13. a second silicon dioxide layer; 14. a second under-oxidized aluminum oxide layer; 15. a second oxygen-enriched alumina layer; 16. second SiN x A layer; 17. a first aluminum oxide layer; 18. a second aluminum oxide layer; 19. a first metal electrode; 20. tunneling oxide layer; 21. an n+ doped polysilicon layer; 22. a second metal electrode.
Detailed Description
According to the utility model, the efficiency of the crystalline silicon solar cell is further improved under the condition of not increasing the equipment and process cost, so that the production cost of the commercial photovoltaic module is reduced, and the conversion of energy consumption modes is facilitated.
The present utility model will be described in detail with reference to specific examples, but the following examples are not to be construed as limiting the utility model.
Example 1
As shown in fig. 1, the structure of the layered alumina passivation film provided in this embodiment includes, from bottom to top, a P-type silicon substrate 4, a silicon oxide layer 3, an under-oxidized alumina layer 2, and an oxygen-enriched alumina layer 1. Under-oxidized alumina layer 2 and richAlumina layer 1, i.e. layered Al forming an oxygen gradient 2 O 3 And (3) a passivation film. The thickness of the silicon oxide layer is 1nm, the thickness of the under-oxygen alumina layer is 0.5nm, and the thickness of the oxygen-rich alumina layer is 0.5nm.
The preparation process of the layered alumina passivation film specifically comprises the following steps:
(1) P-type silicon with the thickness of 150-170 mu m and the resistivity of 0.3-2 omega cm and the size of 156.75mm multiplied by 156.75mm is selected as a substrate, and HF acid is adopted to remove the surface natural oxide layer.
(2) And preparing an ultrathin silicon oxide layer on one side of the etched P-type silicon by adopting a high-temperature thermal oxidation method. Specifically, under the conditions of normal pressure, pure oxygen and 1040 ℃, the reaction is carried out for 10min, and the thickness of the silicon oxide layer is 1nm.
In this step, the silicon oxide layer may be prepared by a nitric acid oxidation method or an ozone oxidation method; wherein, the nitric acid oxidation method adopts 45-60% nitric acid solution by mass fraction, and reacts for 4-10 min at the reaction temperature of 90-115 ℃.
(3) Deposition of layered Al on a silicon oxide layer 2 O 3 Passivation film, layered Al 2 O 3 The passivation film is divided into an under-oxidized alumina layer 2 and an oxygen-enriched alumina layer 1. Trimethylaluminum and H using ALD deposition methods 2 O gas, the process temperature is 250 ℃. First, an under-oxidized alumina layer 2 is deposited, and H is a growth cycle of alumina 2 The aeration time of O is 3 seconds, and the aeration time of trimethylaluminum is 5 seconds; the thickness of the under-oxidized aluminum oxide layer is 0.5nm after a plurality of cycles. Redeposit of the oxygen-enriched alumina layer 1, H during an alumina growth cycle 2 The aeration time of O is 6 seconds, and the aeration time of trimethylaluminum is 5 seconds; the thickness of the oxygen-enriched alumina layer after a plurality of cycles is 0.5nm. Deposition of layered Al 2 O 3 After passivating the film, it was annealed at a high temperature of 350℃for 30min.
In this example, the XPS spectrum of the alumina rich layer 1 is shown in FIG. 2, and a distinct oxygen characteristic peak can be found. The XPS spectrum of the under-oxidized alumina layer 2 is shown in FIG. 3, and no characteristic peak of oxygen is found in FIG. 3. This indicates that the oxygen content in the oxygen-enriched alumina film in this example is higher than that in the oxygen-deficient alumina film. This also means that the present example successfully achieved layered alumina films with graded changes, the structure having a graded field passivation effect.
Example 2
As shown in fig. 4, the structure of the layered alumina passivation film provided in this embodiment sequentially includes, from bottom to top: an N-type silicon substrate 6, a P+ doped layer 5, a silicon oxide layer 3, an under-oxidized aluminum oxide layer 2 and an oxygen-enriched aluminum oxide layer 1. The underoxidized alumina layer 2 and the oxygen-enriched alumina layer 1 are layered Al forming oxygen gradient 2 O 3 And (3) a passivation film. The thickness of the silicon oxide layer is 1nm, the thickness of the under-oxygen alumina layer is 0.5nm, and the thickness of the oxygen-rich alumina layer is 0.5nm.
The preparation process of the layered alumina passivation film specifically comprises the following steps:
(1) N-type silicon with the thickness of 150-170 mu m and the resistivity of 0.3-2 omega cm and the size of 156.75mm multiplied by 156.75mm is selected as a substrate, and HF acid is adopted to remove the surface natural oxide layer.
(2) And preparing a P+ doped region on the surface of the treated N-type silicon by adopting boron tribromide as a boron source, wherein the diffusion temperature is 850-1000 ℃, the diffusion time is 50-80 min, and the sheet resistance is 80-100 omega/sq, so that a P+ doped layer is formed.
(3) And preparing an ultrathin silicon oxide layer on the P+ doped layer by adopting a high-temperature thermal oxidation method. Specifically, under the conditions of normal pressure, pure oxygen and 1040 ℃, the reaction is carried out for 10min, and the thickness of the silicon oxide layer is 1nm.
In this step, the silicon oxide layer may be prepared by a nitric acid oxidation method or an ozone oxidation method; wherein, the nitric acid oxidation method adopts 45-60% nitric acid solution by mass fraction, and reacts for 4-10 min at the reaction temperature of 90-115 ℃.
(4) Deposition of layered Al on a silicon oxide layer 2 O 3 Passivation film, layered Al 2 O 3 The passivation film is divided into an under-oxidized aluminum oxide layer and an oxygen-enriched aluminum oxide layer. Trimethylaluminum and O using ALD deposition 3 The gas, the process temperature was 250 ℃. Firstly, depositing an under-oxidized alumina layer, O in an alumina growth cycle 3 Is 2 seconds, and trimethylaluminum is aeratedThe time is 4 seconds; the thickness of the deposited under-oxidized aluminum oxide layer was 0.5nm. Redeposition of the oxygen-enriched alumina layer, O during an alumina growth cycle 3 The aeration time of (2) was 7 seconds and that of trimethylaluminum was 4 seconds; the thickness of the deposited oxygen enriched alumina layer was 0.5nm. Deposition of layered Al 2 O 3 After passivating the film, it was annealed at a high temperature of 350℃for 30min.
Also, layered Al obtained in the present example 2 O 3 Passivation film and layered Al in example 1 2 O 3 The passivation film is similar in that the oxygen content in the oxygen-enriched alumina film is higher than the oxygen content in the oxygen-deficient alumina film.
Example 3
The present embodiment provides a SiN x Delamination Al 2 O 3 /SiO 2 P+ doped/N-Si/P+ doped/SiO 2 Delamination Al 2 O 3 /SiN x As shown in FIG. 5, the device comprises an N-type silicon substrate 6, a first P+ doped layer 7, a first silicon oxide layer 8, a first under-oxidized aluminum oxide layer 9, a first oxygen-enriched aluminum oxide layer 10, and a first SiN sequentially arranged on the front surface of the N-type silicon substrate 6 x A layer 11, a second P+ doped layer 12, a second silicon dioxide layer 13, a second under-oxidized aluminum oxide layer 14, a second oxygen-enriched aluminum oxide layer 15, and a second SiN are sequentially arranged on the back surface of the N-type silicon substrate 6 x Layer 16.
SiN of the present embodiment x Delamination Al 2 O 3 /SiO 2 P+ doped/N-Si/P+ doped/SiO 2 Delamination Al 2 O 3 /SiN x The preparation method of the double-sided symmetrical passivation structure device comprises the following steps:
(1) N-type silicon with the thickness of 150-170 mu m and the resistivity of 0.3-2 omega cm and the size of 156.75mm multiplied by 156.75mm is selected as a substrate, and HF acid is adopted to clean surface natural oxide.
(2) And preparing a double-sided P+ doped region on the surface of the N-type silicon subjected to acid treatment by adopting boron tribromide as a boron source, wherein the diffusion temperature is 850-1000 ℃, the diffusion time is 50-80 min, the sheet resistance is 80-100 omega/sq, and a first P+ doped layer and a second P+ doped layer are respectively formed on the front surface and the back surface of the N-type silicon substrate.
(3) And (3) nitric acid oxidation is carried out on the P+ doped regions on two sides of the N-type silicon to form a first silicon oxide layer and a second silicon oxide layer respectively.
(4) Layered Al is deposited on the silicon oxide layers on both sides of the substrate 2 O 3 And (3) a passivation film. Layered Al on a first silicon oxide layer 2 O 3 The passivation film comprises a first under-oxidized aluminum oxide layer and a first oxygen-enriched aluminum oxide layer, and layered Al on the second silicon oxide layer 2 O 3 The passivation film includes a second under-oxidized aluminum oxide layer and a second oxygen-enriched aluminum oxide layer. The first under-oxidized aluminum oxide layer, the first oxygen-enriched aluminum oxide layer, the second under-oxidized aluminum oxide layer and the second oxygen-enriched aluminum oxide layer are all prepared by adopting an ALD deposition method, and trimethylaluminum gas and H are adopted 2 O gas is used as a gas source, and the process temperature is set to be 250 ℃. In the deposition of the first and second under-oxidized aluminum oxide layers, H is in one alumina growth cycle 2 The aeration time of O is 3 seconds, and the aeration time of trimethylaluminum is 5 seconds; the thickness of the deposited first and second under-oxidized aluminum oxide layers was 0.5nm. In the deposition of the first oxygen-enriched alumina layer and the second oxygen-enriched alumina layer, H is in one alumina growth cycle 2 The aeration time of O is 8 seconds, and the aeration time of trimethylaluminum is 5 seconds; the thickness of the deposited first and second oxygen-enriched alumina layers was 0.5nm.
(5) Layered Al on both sides of the substrate 2 O 3 Respectively depositing a layer of SiN on the passivation film x Passivating the antireflection film. Deposition of SiN x Passivation of the anti-reflective film is performed at a high temperature of 600 ℃, and thus, layered Al is deposited in step (4) 2 O 3 The passivation film is not annealed at high temperature.
Comparative example 1
In comparison with example 3, this comparative example provides a SiN x Monolayer Al 2 O 3 /SiO 2 P+ doped/N-Si/P+ doped/SiO 2 Monolayer Al 2 O 3 /SiN x As shown in FIG. 6, the device with double-sided symmetrical passivation structure comprises an N-type silicon substrate 6, and a first P+ doped layer 7 and a first oxide layer are sequentially arranged on the front surface of the N-type silicon substrate 6Silicon layer 8, first aluminum oxide layer 17, first SiN x A second P+ doped layer 12, a second silicon oxide layer 13, a second aluminum oxide layer 18, and a second SiN layer are sequentially arranged on the back surface of the N-type silicon substrate 6 x Layer 16. This comparative example differs from example 3 in that in example 3 is layered Al 2 O 3 Passivation film (including under-oxidized aluminum oxide layer and oxygen-enriched aluminum oxide layer), in this comparative example, a single layer of Al 2 O 3 A film.
SiN provided in this comparative example x Monolayer Al 2 O 3 /SiO 2 P+ doped/N-Si/P+ doped/SiO 2 Monolayer Al 2 O 3 /SiN x The preparation method of the device with the double-sided symmetrical passivation structure comprises the following steps:
(1) N-type silicon with the thickness of 150-170 mu m and the resistivity of 0.3-2 omega cm and the size of 156.75mm multiplied by 156.75mm is selected as a substrate, and HF acid is adopted to clean surface natural oxide.
(2) And preparing a double-sided P+ doped region on the surface of the N-type silicon subjected to acid treatment by adopting boron tribromide as a boron source, wherein the diffusion temperature is 850-1000 ℃, the diffusion time is 50-80 min, the sheet resistance is 80-100 omega/sq, and a first P+ doped layer and a second P+ doped layer are respectively formed on the front surface and the back surface of the N-type silicon substrate.
(3) And (3) nitric acid oxidation is carried out on the P+ doped regions on two sides of the N-type silicon to form a first silicon oxide layer and a second silicon oxide layer respectively.
(4) Depositing single-layer Al on silicon oxide layers on two sides of substrate 2 O 3 Passivation film, namely: a first aluminum oxide layer is deposited over the first silicon oxide layer and a second aluminum oxide layer is deposited over the second silicon oxide layer. Trimethylaluminum and H using ALD deposition methods 2 O gas is used as a gas source, and the process temperature is 250 ℃. In the deposition of the first alumina layer and the second alumina layer, H is in a growth cycle of alumina 2 The aeration time for O was 5 seconds and for trimethylaluminum 5 seconds. The thickness of the deposited first and second alumina layers was 1nm.
(5) Single layer of Al on both sides of the substrate 2 O 3 Respectively depositing a layer of SiN on the passivation film x The anti-reflection film is passivated and the anti-reflection film is also passivated,namely: depositing a first SiN on the first alumina layer x A layer of a second SiN deposited on the second alumina layer x A layer. Deposition of first SiN x Layer and second SiN x The layer is carried out at a high temperature of 600 ℃.
The device of the double-sided symmetrical passivation structure obtained in example 3 and comparative example 1 was subjected to the iVoc test, and as shown in fig. 7, it can be seen from fig. 7 that the device of the double-sided symmetrical passivation structure of the layered aluminum oxide film prepared in example 3 was higher than that of the device of the double-sided symmetrical passivation structure of the single-layered aluminum oxide film in comparative example 1.
Example 4
As shown in fig. 8, the present embodiment provides an N-type TOPCon passivation contact structure crystalline silicon solar cell, which comprises an N-type silicon substrate 6, wherein a p+ doped layer 5, a silicon oxide layer 3, an under-oxidized aluminum oxide layer 2, an oxygen-enriched aluminum oxide layer 1, and a first SiN are sequentially disposed on the front surface of the N-type silicon substrate 6 x A layer 11, a first metal electrode 19, a tunneling oxide layer 20, an N+ doped polysilicon layer 21, and a second SiN layer sequentially arranged on the back surface of the N-type silicon substrate 6 x Layer 16, second metal electrode 22.
The preparation method of the N-type TOPCon passivation contact structure crystalline silicon solar cell provided by the embodiment comprises the following steps:
(1) N-type silicon with the thickness of 150-170 mu m and the resistivity of 0.3-2 omega cm and the size of 156.75mm multiplied by 156.75mm is selected as a substrate for double-sided texturing treatment.
(2) And preparing a double-sided P+ doped region on the surface of the N-type silicon subjected to the texturing treatment by adopting boron tribromide as a boron source, wherein the diffusion temperature is 850-1000 ℃, the diffusion time is 50-80 min, the sheet resistance is 80-100 omega/sq, and P+ doped layers are formed on the front surface and the back surface of the N-type silicon substrate.
(3) The N-type silicon with double-sided boron diffusion is selected to be put into HF and HNO on the back 3 And H 2 SO 4 Etching in the mixed solution to remove the P+ doped region on the back surface and obtain a gentle pyramid surface after etching, wherein the volume ratio of each substance is HF to HNO 3 :H 2 SO 4 :H 2 O=1:4:0.6:3, hf mass fraction 20%.
(4) And preparing an ultrathin tunneling oxide layer on the back surface of the etched N-type silicon by adopting a high-temperature thermal oxidation method. Specifically, under the conditions of normal pressure, pure oxygen and temperature of more than 1000 ℃, the tunneling oxide layer is obtained by reacting for 10-20 min, and the thickness of the tunneling oxide layer is 1-3 nm.
It should be noted that, in this step, the tunnel oxide layer may also be prepared by setting a nitric acid oxidation method or an ozone oxidation method; wherein, the nitric acid oxidation method adopts 45-60% nitric acid solution by mass fraction, and the reaction is carried out for 4-10 min at the reaction temperature of 90-115 ℃.
(5) And preparing an N+ doped polycrystalline silicon film. An intrinsic polysilicon film is prepared by LPCVD. The deposition temperature of the intrinsic polycrystalline silicon layer is 550-650 ℃, the thickness of the intrinsic polycrystalline silicon layer is 50-400 nm, and the front surface can be subjected to coiling plating. And doping the intrinsic polycrystalline silicon layer in a manner of ion implantation of phosphorus atoms, specifically, the radio frequency power is 500-2000W, the process pressure is 1E-7-8E-5 Torr, and the reaction time is 1-20 min. Finally, the phosphorus doped polysilicon film is formed. And performing RCA cleaning on the doped N-type silicon to remove surface metal ions. Carrying out rapid thermal annealing treatment on the N-type silicon cleaned by RCA, and vacuumizing the annealing furnace to 10 -4 pa, and then charging nitrogen as a shielding gas. The vacuum degree of the annealing furnace is 500-950 mbar, the annealing time is 20-60 min, the annealing temperature is 800-900 ℃, and the N+ doped polysilicon layer is formed on the back surface of the annealed N-type silicon.
(6) SiN is adopted for the N+ doped polysilicon layer on the back surface of the N-type silicon x A single-layer passivation structure of a passivation film, namely: forming a second SiN on the N+ doped polysilicon layer x And (3) carrying out BOE cleaning on the silicon wafer, washing off POLY coiling plating on the front surface, and carrying out nitric acid oxidation on the P+ doped region on the front surface of the N-type silicon by adopting silicon oxide to form a silicon oxide layer on the front surface.
(7) Deposition of layered Al on a silicon oxide layer on the front side of a substrate 2 O 3 Passivation film, layered Al 2 O 3 The passivation film includes an under-oxidized aluminum oxide layer and an oxygen-enriched aluminum oxide layer. The under-oxidized aluminum oxide layer and the oxygen-enriched aluminum oxide layer are prepared by adopting an ALD deposition method and are prepared by trimethyl aluminum and H 2 O gas asIs used as an air source, and the process temperature is 250 ℃. First, an under-oxidized alumina layer is deposited, H in an alumina growth cycle 2 The aeration time of O is 3 seconds, and the aeration time of trimethylaluminum is 5 seconds; the thickness of the deposited under-oxidized aluminum oxide layer was 0.5nm. Redeposition of the oxygen-enriched alumina layer, H in an alumina growth cycle 2 The aeration time of O is 6 seconds, and the aeration time of trimethylaluminum is 5 seconds; the thickness of the deposited oxygen enriched alumina layer was 0.5nm.
(8) Layered Al on the front side of the substrate 2 O 3 Depositing a layer of SiN on the passivation film x Passivation antireflection film, namely: formation of a first SiN on an oxygen-enriched alumina layer x A layer. Deposition of first SiN x The layer is carried out at a high temperature of 600 ℃.
(9) Printing a first metal electrode 19 on the front surface of the N-type silicon substrate by adopting silver-aluminum paste, and sintering at a high temperature; the second metal electrode 22 is printed with silver paste on the back side of the N-type silicon substrate and sintered at high temperature. Wherein the temperature is 700-900 ℃, and the number of the fine grids on the front and the back is 106.
Claims (4)
1. The layered alumina passivation film is characterized by sequentially comprising a silicon substrate, a silicon oxide layer, an under-oxidized alumina layer and an oxygen-enriched alumina layer from bottom to top; the silicon substrate is P-type monocrystalline silicon, P-type polycrystalline silicon or N-type monocrystalline silicon or N-type polycrystalline silicon after boron doping.
2. The layered aluminum oxide passivation film according to claim 1, wherein the thickness of the silicon oxide layer is 0.5nm to 3nm; the thickness of the under-oxidized aluminum oxide layer is 0.5-5nm, and the thickness of the oxygen-enriched aluminum oxide layer is 0.5-5nm.
3. The crystalline silicon solar cell prepared based on the layered alumina passivation film is characterized in that the crystalline silicon solar cell is a P-type perc cell or an N-type TOPCON cell; the layered aluminum oxide passivation film according to any one of claims 1 to 2 is used in the structure of the crystalline silicon solar cell.
4. The crystalline silicon solar cell of claim 3, wherein the crystalline silicon solar cell is an N-type TOPCon cell; the structure of the N-type TOPCON battery comprises an N-type silicon substrate, wherein a P+ doped layer, a silicon oxide layer, an under-oxidized aluminum oxide layer, an oxygen-enriched aluminum oxide layer and a first SiN are sequentially arranged on the front surface of the N-type silicon substrate x A tunneling oxide layer, an N+ doped polysilicon layer and a second SiN layer are sequentially arranged on the back surface of the N-type silicon substrate x Layer, second metal electrode.
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