CN113621946A - Laminated back film and preparation method thereof - Google Patents
Laminated back film and preparation method thereof Download PDFInfo
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- CN113621946A CN113621946A CN202110884411.1A CN202110884411A CN113621946A CN 113621946 A CN113621946 A CN 113621946A CN 202110884411 A CN202110884411 A CN 202110884411A CN 113621946 A CN113621946 A CN 113621946A
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- 238000002360 preparation method Methods 0.000 title abstract description 16
- 238000000151 deposition Methods 0.000 claims abstract description 126
- 239000010703 silicon Substances 0.000 claims abstract description 95
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 95
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 93
- 230000008021 deposition Effects 0.000 claims abstract description 87
- 239000007789 gas Substances 0.000 claims abstract description 78
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims abstract description 65
- 229910052581 Si3N4 Inorganic materials 0.000 claims abstract description 60
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims abstract description 59
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 36
- 229910052814 silicon oxide Inorganic materials 0.000 claims abstract description 35
- 239000011265 semifinished product Substances 0.000 claims abstract description 25
- 239000000047 product Substances 0.000 claims abstract description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 5
- 239000001301 oxygen Substances 0.000 claims abstract description 5
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 5
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 claims description 86
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims description 43
- 235000013842 nitrous oxide Nutrition 0.000 claims description 43
- 229910000077 silane Inorganic materials 0.000 claims description 42
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 36
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 34
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 32
- 229910002804 graphite Inorganic materials 0.000 claims description 32
- 239000010439 graphite Substances 0.000 claims description 32
- 238000000034 method Methods 0.000 claims description 26
- 229910052757 nitrogen Inorganic materials 0.000 claims description 18
- 238000011068 loading method Methods 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 11
- 229910021529 ammonia Inorganic materials 0.000 claims description 6
- 230000001681 protective effect Effects 0.000 claims description 6
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 4
- 229910052786 argon Inorganic materials 0.000 claims description 2
- 239000010410 layer Substances 0.000 abstract description 146
- 238000002161 passivation Methods 0.000 abstract description 27
- 230000000694 effects Effects 0.000 abstract description 26
- 239000002356 single layer Substances 0.000 abstract description 5
- 239000010408 film Substances 0.000 description 92
- 238000000231 atomic layer deposition Methods 0.000 description 18
- 239000001257 hydrogen Substances 0.000 description 17
- 229910052739 hydrogen Inorganic materials 0.000 description 17
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 10
- 238000012360 testing method Methods 0.000 description 9
- 238000007599 discharging Methods 0.000 description 8
- 239000007888 film coating Substances 0.000 description 8
- 238000009501 film coating Methods 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 8
- 238000003825 pressing Methods 0.000 description 8
- 239000000243 solution Substances 0.000 description 8
- 101001073212 Arabidopsis thaliana Peroxidase 33 Proteins 0.000 description 6
- 101001123325 Homo sapiens Peroxisome proliferator-activated receptor gamma coactivator 1-beta Proteins 0.000 description 6
- 102100028961 Peroxisome proliferator-activated receptor gamma coactivator 1-beta Human genes 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- 101100409194 Rattus norvegicus Ppargc1b gene Proteins 0.000 description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 5
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 5
- 239000013078 crystal Substances 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 4
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- -1 hydrogen ions Chemical class 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000007650 screen-printing Methods 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- UMVBXBACMIOFDO-UHFFFAOYSA-N [N].[Si] Chemical compound [N].[Si] UMVBXBACMIOFDO-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- PZPGRFITIJYNEJ-UHFFFAOYSA-N disilane Chemical compound [SiH3][SiH3] PZPGRFITIJYNEJ-UHFFFAOYSA-N 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
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- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
- C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
- C23C16/505—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using radio frequency discharges
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- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
- C23C16/308—Oxynitrides
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- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
- C23C16/34—Nitrides
- C23C16/345—Silicon nitride
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- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
- C23C16/40—Oxides
- C23C16/401—Oxides containing silicon
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- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
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- C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
- C23C16/40—Oxides
- C23C16/403—Oxides of aluminium, magnesium or beryllium
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- C23C16/45523—Pulsed gas flow or change of composition over time
- C23C16/45525—Atomic layer deposition [ALD]
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- H01L31/02—Details
- H01L31/0216—Coatings
- H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
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- H01L31/186—Particular post-treatment for the devices, e.g. annealing, impurity gettering, short-circuit elimination, recrystallisation
- H01L31/1868—Passivation
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Abstract
The invention provides a laminated back film and a preparation method thereof. The preparation method comprises the following steps: 1) placing a silicon wafer with an aluminum oxide layer deposited on one surface in a reactor, vacuumizing, and introducing first gas to perform pre-deposition on the aluminum oxide layer to obtain a first semi-finished product; the first gas is an oxygen-containing gas; 2) introducing a second gas, and depositing a silicon oxide layer on the aluminum oxide layer of the pretreated product to obtain a second semi-finished product; 3) introducing a third gas, and depositing a silicon oxynitride layer on the silicon oxide layer of the second semi-finished product to obtain a third semi-finished product; 4) and introducing fourth gas, and depositing a silicon nitride layer on the silicon oxynitride layer of the third semi-finished product to obtain the laminated back film. The surface negative charge density and the passivation effect can be enhanced by adopting the O-containing gas to pretreat the surface of the aluminum oxide. The single-layer silicon nitride film layer in the prior art is replaced by the back silicon oxide layer and the silicon oxynitride layer which are superposed, so that the LeTID phenomenon of the battery piece is improved.
Description
Technical Field
The invention belongs to the technical field of solar cells, relates to a laminated back film and a preparation method thereof, and particularly relates to a laminated back film suitable for a solar perc cell and a preparation method thereof.
Background
Solar single crystal perc cell technology is the mainstream in the industry at present. The p-type PERC + LDSE process flow comprises the following steps: alkali texturing → diffusion → LDSE → etching → oxidation → alumina → front and back PECVD → laser windowing → silk screen printing → sintering. The aluminum oxide in the PERC technology is a back passivation technology which is widely applied, the main reason is that the preparation process is simple and the conversion efficiency is high, and the aluminum oxide passivation layer is formed on the surface of the solar cell, so that the back electrical recombination can be greatly reduced, the open-circuit voltage and the short-circuit current of the cell are improved, and the conversion efficiency is improved.
In the existing perc cell technology, the aluminum oxide passivation layer is generally formed by Atomic Layer Deposition (ALD) and tubular PECVD.
CN111416002A discloses a battery back silicon nitride film layer, a PERC battery and a preparation method, and belongs to the field of single crystal PERC battery manufacturing. The battery comprises a front silicon nitride film layer, a back aluminum oxide film layer and a back silicon nitride film layer, wherein the back silicon nitride film layer is of a five-layer structure. In the scheme of the back film in the document, the silicon-nitrogen ratio is gradually reduced, namely, the refractive index of the back film layer is gradually reduced from the inner side to the outer film layer from the bottom silicon layer, so that the wavelength response is poor, and the conversion efficiency is influenced. And all use the special gas containing hydrogen, can produce a large amount of hydrogen ions in the course of technology, can lead to the battery to appear light and heat decay (LeTID), influence the reliability of battery.
CN111029436A the invention provides a method for manufacturing a P-type single crystal PERC battery capable of improving the LeTID phenomenon. The hydrogen source sources are reduced by changing the structure of the battery film layer, manufacturing raw materials and a corresponding process optimization method, redundant hydrogen atoms in the solar cell are reduced, and the technical effect of improving the LeTID phenomenon of the solar cell is achieved. In order to improve the LeTID phenomenon, the back film passivation layer is mainly a silicon oxynitride film with the thickness of 110nm, so that the content of the whole hydrogen ions is low, the passivation effect of hydrogen is weakened in the electric injection/light injection process, the light attenuation of a battery is increased, and the PID reliability of the assembly is influenced.
Disclosure of Invention
In view of the above-mentioned disadvantages in the prior art, the present invention is directed to a laminated back film and a method for manufacturing the same. The laminated back film preparation method provided by the invention has lower requirement on the thickness of the aluminum oxide layer, the thinner aluminum oxide can achieve excellent passivation effect, and meanwhile, the preparation method provided by the invention can reduce the LeTID phenomenon of the solar cell.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for preparing a laminated back film, the method comprising the steps of:
(1) placing a silicon wafer with an aluminum oxide layer deposited on one surface in a reactor, vacuumizing, and introducing first gas to perform pre-deposition on the aluminum oxide layer to obtain a first semi-finished product; the first gas is an oxygen-containing gas;
(2) introducing a second gas, and depositing a silicon oxide layer on the aluminum oxide layer of the pretreated product in the step (1) to obtain a second semi-finished product;
(3) introducing a third gas, and depositing a silicon oxynitride layer on the silicon oxide layer of the second semi-finished product in the step (2) to obtain a third semi-finished product;
(4) and (4) introducing fourth gas, and depositing a silicon nitride layer on the silicon oxynitride layer of the third semi-finished product in the step (3) to obtain the laminated back film.
The applicant has found that in perc cell technology, the alumina layer prepared by Atomic Layer Deposition (ALD) has good uniformity and the quality and thickness of the passivation layer can be accurately controlled, but the production speed is slow. In order to increase the yield and reduce the cost, the thickness of the aluminum oxide layer needs to be reduced. After the thickness of the aluminum oxide layer is reduced, the passivation effect of the aluminum oxide is weakened, and the conversion efficiency of the cell is reduced.
Further, the conventional solar perc cell has Light Induced Degradation (LID) and light-heat degradation (LeTID) phenomena. Research shows that the LeTID is mainly caused by the existence of redundant hydrogen atoms, impurities, defects and the like in the battery piece. Wherein hydrogen atoms are generated during the normal process of preparing the battery: when the front SiyNx thin film is deposited by the PECVD method and the SiyNx laminated film is deposited on the back, a large amount of hydrogen-containing gas is used, and finally, a large amount of hydrogen atoms appear in the cell, so that the LeTID phenomenon is aggravated.
According to the preparation method provided by the invention, the surface of the aluminum oxide is pretreated by adopting the gas containing O, so that the surface negative charge density can be enhanced, the passivation effect can be enhanced, and the passivation effect of the back film can be enhanced by adopting the silicon oxynitride film layer. Through the method, the problems that negative charges on the passivated surface of the aluminum oxide are reduced and the passivation effect of the aluminum oxide is weakened after the thickness of the aluminum oxide layer is reduced are solved.
The preparation method provided by the invention also replaces the single-layer silicon nitride film layer in the prior art by superposing the silicon nitride layer on the back silicon oxide layer and the silicon oxynitride layer, so that the use amount of hydrogen-containing source gases (ammonia gas and the like) is reduced, the hydrogen atomic weight in the battery is reduced, and the LeTID phenomenon of the battery piece is improved.
The following is a preferred technical solution of the present invention, but not a limitation to the technical solution provided by the present invention, and the technical objects and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solution.
As a preferred technical solution of the present invention, the method of placing in a reactor in step (1) comprises: and loading the silicon wafer with the aluminum oxide layer deposited on one surface into a graphite boat, and then placing the graphite boat into a reactor.
Preferably, the thickness of the aluminum oxide layer of the silicon wafer with the aluminum oxide layer deposited on one side in the step (1) is 3-4 μm, such as 3 μm, 3.5 μm or 4 μm. The aluminum oxide layer with the smaller thickness can realize good passivation effect by the method provided by the invention.
Preferably, a PN junction is arranged in the silicon wafer with the aluminum oxide layer deposited on one surface in the step (1).
As a preferred technical solution of the present invention, the first gas in step (1) comprises laughing gas.
Preferably, the flow rate of the first gas in step (1) is 2000sccm and 5000sccm, such as 2000sccm, 3000sccm, 4000sccm, or 5000 sccm.
Preferably, the temperature for the pre-deposition in step (1) is 350-. In the invention, if the temperature of the pre-deposition is too high, the alumina layer can be damaged due to strong oxidizing property of laughing gas; if the thickness of the pre-deposition is too low, the pre-treatment effect is reduced.
Preferably, the RF power for the pre-deposition in step (1) is 4000-.
Preferably, the duty cycle of the pre-deposition of step (1) is 1: (10-30), for example, 1: 10. 1: 15. 1: 20. 1: 25 or 1:30, etc.
Preferably, the pressure of the pre-deposition reactor in the step (1) is 200-250Pa, such as 200Pa, 210Pa, 220Pa, 230Pa, 240Pa or 250Pa, etc.
As a preferred technical solution of the present invention, the second gas in step (2) includes laughing gas and silane. In the present invention, the silane means a compound of silicon and hydrogen, such as monosilane (SiH)4) Disilane (Si)2H6) And the like.
Preferably, the flow rate of laughing gas in the second gas is 4000-7000sccm, such as 4000sccm, 5000sccm, 6000sccm or 7000sccm, and the flow rate of silane is 500-1000sccm, such as 500sccm, 600sccm, 700sccm, 800sccm, 900sccm or 1000 sccm.
Preferably, the deposition temperature in step (2) is 450-550 ℃, such as 450 ℃, 475 ℃, 500 ℃, 525 ℃ or 550 ℃, etc.
Preferably, the RF power for the deposition in step (2) is 5000-8000W, such as 5000W, 6000W, 7000W or 8000W.
Preferably, the duty cycle of the deposition of step (2) is 1: (10-30), for example, 1: 10. 1:20 or 1:30, etc.
Preferably, the pressure of the reactor for the deposition in the step (2) is 200-250Pa, such as 200Pa, 210Pa, 220Pa, 230Pa, 240Pa or 250Pa, etc.
Preferably, the silicon oxide layer deposited in step (2) has a thickness of 5-10 μm, such as 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. In the invention, the thickness of the silicon oxide layer is too high, and the subsequent wire mesh metallization sintering and electrical injection hydrogen passivation effects are influenced by the too thick silicon oxide layer due to good compactness; the thickness of the silicon oxide layer is too low, so that the thickness of the whole back film is too low, other film layers are required to be thickened, hydrogen atoms are excessively introduced, and the LeTID phenomenon is increased.
As a preferred technical scheme of the invention, the third gas in the step (3) comprises laughing gas, silane and ammonia gas.
Preferably, in the third gas, the flow rate of laughing gas is 1500-.
Preferably, the deposition temperature in step (3) is 450-550 ℃, such as 450 ℃, 470 ℃, 490 ℃, 510 ℃, 530 ℃ or 550 ℃.
Preferably, the RF power for the deposition in step (3) is 5000-12000W, such as 5000W, 6000W, 7000W, 8000W or 12000W.
Preferably, the duty cycle of the deposition of step (3) is 1: (10-30), for example, 1: 10. 1: 15. 1: 20. 1: 25 or 1:30, etc.
Preferably, the pressure of the reactor for the deposition in the step (3) is 200-250Pa, such as 200Pa, 210Pa, 220Pa, 230Pa, 240Pa or 250Pa, etc.
Preferably, the silicon oxynitride layer deposited in step (3) has a thickness of 60-90 μm, such as 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, or 90 μm. In the invention, if the thickness of the silicon oxynitride layer is too high, the yield of a back film process is reduced, and the contact position of the local part of the silicon wafer and the graphite boat is burnt and cracked due to an excessively thick film layer; if the thickness of the silicon oxynitride layer is too low, the passivation effect of the back film is weakened, and the efficiency of the cell is affected.
Preferably, the refractive index of the silicon oxynitride layer deposited in step (3) is 1.85-2.0, such as 1.85, 1.9, 1.95, or 2.0.
As a preferred technical scheme of the invention, the fourth gas in the step (4) comprises silane and ammonia.
Preferably, the flow rate of silane in the fourth gas is 500-1500sccm, such as 500sccm, 800sccm, 1000sccm, 1300sccm or 1500sccm, etc., and the flow rate of ammonia is 5000-10000sccm, such as 5000sccm, 6000sccm, 7000sccm, 8000sccm, 9000sccm or 10000sccm, etc.
Preferably, the deposition temperature in step (4) is 450-550 ℃, such as 450 ℃, 460 ℃, 470 ℃, 480 ℃, 490 ℃, 500 ℃ or 550 ℃.
Preferably, the RF power of the deposition in step (4) is 9000-13000W, such as 9000W, 10000W, 11000W, 12000W or 13000W.
Preferably, the duty cycle of the deposition of step (4) is 1: (5-20), for example 1: 5. 1: 10. 1:15 or 1:20, etc.
Preferably, the pressure of the reactor for the deposition in the step (4) is 200-250Pa, such as 200Pa, 210Pa, 220Pa, 230Pa, 240Pa or 250Pa, etc.
Preferably, the silicon nitride layer deposited in step (4) has a thickness of 50-80 μm, such as 50 μm, 60 μm, 70 μm, or 80 μm. In the invention, if the thickness of the silicon nitride layer is too high, the overall yield of the back process is reduced, and the excessively thick silicon nitride layer affects the laser windowing effect (the laser power is increased and the windowing speed is reduced) of the subsequent process; if the thickness of the silicon nitride layer is too low, the passivation effect is weakened, and the efficiency of the cell is affected.
Preferably, the deposited silicon nitride layer of step (4) has a refractive index of 2.0-2.1, such as 2.0, 2.05 or 2.1.
As a preferred technical solution of the present invention, the method further comprises: after the silicon nitride layer is deposited, the operations of vacuumizing and introducing protective gas are repeated, and then the product is taken out.
Preferably, the protective gas comprises nitrogen and/or argon.
As a further preferable technical scheme of the preparation method, the method comprises the following steps:
(1) loading a silicon wafer with an aluminum oxide layer deposited on one surface into a graphite boat, then placing the graphite boat into a reactor, vacuumizing, and introducing first gas to pre-deposit the aluminum oxide layer to obtain a first semi-finished product; the first gas is an oxygen-containing gas; the first gas comprises laughing gas, and the flow rate of the laughing gas is 2000-; the temperature of the pre-deposition is 350-400 ℃; the radio frequency power of the pre-deposition is 4000-; duty cycle of predeposition is 1: (10-30); the pressure of the pre-deposition reactor is 200-250 Pa;
(2) introducing a second gas, and depositing a silicon oxide layer on the aluminum oxide layer of the pretreated product in the step (1) to obtain a second semi-finished product; the second gas comprises laughing gas and silane, wherein the flow rate of the laughing gas is 4000-7000sccm, and the flow rate of the silane is 500-1000 sccm; the deposition temperature in the step (2) is 450-: (10-30), the pressure of the deposition reactor is 200-250 Pa;
(3) introducing a third gas, and depositing a silicon oxynitride layer on the silicon oxide layer of the second semi-finished product in the step (2) to obtain a third semi-finished product; the third gas comprises laughing gas, silane and ammonia gas, wherein the flow rate of the laughing gas is 1500-; the deposition temperature in the step (3) is 450-: (10-30), the pressure of the deposition reactor is 200-250 Pa;
(4) introducing fourth gas, depositing a silicon nitride layer on the silicon oxynitride layer of the third semi-finished product in the step (3), repeatedly vacuumizing and introducing protective gas, and taking out the graphite boat to obtain the laminated back film; the fourth gas comprises silane and ammonia, the flow rate of the silane is 500-; the deposition temperature in the step (4) is 450-: (5-20), the pressure of the deposition reactor is 200-250 Pa.
In a second aspect, the present invention provides a laminated back film prepared by the method of the first aspect.
In a preferred embodiment of the present invention, the back surface of the silicon wafer of the laminated back film is laminated with an aluminum oxide layer, a silicon oxynitride layer, and a silicon nitride layer in this order.
Preferably, a PN junction is arranged in the silicon wafer of the laminated back film.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the preparation method provided by the invention, the surface of the aluminum oxide is pretreated by adopting the gas containing O, so that the surface negative charge density can be enhanced, the passivation effect can be enhanced, and the passivation effect of the back film can be enhanced by adopting the silicon oxynitride film layer. By the method, the problems that negative charges on the passivated surface of the aluminum oxide are reduced and the passivation effect of the aluminum oxide is weakened after the thickness of the aluminum oxide layer is reduced are solved; and a silicon nitride layer is superposed on the back silicon oxide layer and the silicon oxynitride layer to replace a single-layer silicon nitride film layer in the prior art, so that the use amount of hydrogen-containing source gases (ammonia gas and the like) is reduced, the hydrogen atomic weight in the battery is reduced, and the LeTID phenomenon of the battery piece is improved.
(2) The laminated back film provided by the invention reduces the usage amount of hydrogen-containing source gas, reduces the hydrogen atomic weight in the battery piece, weakens LeTID, increases the reliability of the battery, can enhance the back passivation effect and further improves the conversion efficiency of the battery by adjusting the structure of the passivation layer.
Drawings
Fig. 1 is a schematic flow chart of a method for preparing a laminated back film provided in example 1;
fig. 2 is a schematic structural diagram of a laminated back film obtained by the preparation method provided in embodiment 1, wherein the laminated back film includes a 1-silicon wafer, a 2-aluminum oxide layer, a 3-silicon oxide layer, a 4-silicon oxynitride layer, a 5-silicon nitride layer, and a 6-PN junction.
Detailed Description
In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
The following are typical but non-limiting embodiments of the present invention, in which the switching ratio time of the rf power supply is the duty ratio:
example 1
This example prepares a laminated back film as follows:
(1) preparing and feeding a tube, namely loading a silicon wafer (one surface of which is provided with an aluminum oxide layer with the thickness of 4 mu m after ALD (atomic layer deposition), and the silicon wafer contains PN (positive-negative) junctions) into a graphite boat, conveying the graphite boat into a film coating tube, and heating the graphite boat to 350 ℃;
(2) pre-deposition: the temperature in the furnace is kept at 350 ℃, the laughing gas is 4000sccm, the pressure is kept at 230Pa, the radio frequency power is 5000W, and the radio frequency power supply switch ratio time is 1:20, the treatment time is 1.5 minutes;
(3) depositing silicon oxide: the temperature in the furnace is kept at 500 ℃, silane is introduced at 550sccm, laughing gas is introduced at 5000sccm, the pressure is kept at 230Pa, the radio frequency power is 8000W, and the radio frequency power supply switching ratio time is 1:20, deposition time 2 minutes; the thickness of the silicon oxide film is 5 mu m;
(4) depositing silicon oxynitride: the temperature in the furnace is kept at 500 ℃, 400sccm of silane, 6000sccm of ammonia gas and 2000sccm of laughing gas are introduced, the pressure is kept at 230Pa, the radio frequency power is 12000W, the on-off ratio time of the radio frequency power supply is 1:10, and the deposition time is 7 minutes; the thickness of the silicon oxynitride film layer is 60 mu m; the refractive index of the oxynitride film is 1.88;
(5) depositing high-folding silicon nitride: keeping the temperature in the furnace at 490 ℃, introducing 1000sccm of silane and 5000sccm of ammonia gas, keeping the pressure at 230Pa, keeping the radio frequency power at 12500W, keeping the radio frequency power supply on-off ratio time at 1:10, and keeping the deposition time at 8 minutes; the thickness of the silicon nitride layer is 80 mu m; the refractive index of silicon nitride is 2.13;
(6) evacuating, back-pressing, repeatedly vacuumizing, introducing nitrogen, and replacing special gas in the tube to ensure that the tube is full of nitrogen;
(7) and (5) discharging the boat and blanking.
The flow chart of the preparation method of the laminated back film provided by the embodiment is shown in fig. 1.
As shown in fig. 2, the laminated back film structure provided in this embodiment includes an aluminum oxide layer 2, a silicon oxide layer 3, a silicon oxynitride layer 4, and a silicon nitride layer 5 stacked in sequence on the back surface of a silicon wafer 1 of the laminated back film, and a PN junction 6 is disposed in the silicon wafer 1 of the laminated back film.
Example 2
This example prepares a laminated back film as follows:
(1) preparing and feeding a tube, namely loading a silicon wafer (one surface of which is provided with an aluminum oxide layer with the thickness of 4 mu m after ALD (atomic layer deposition), and the silicon wafer contains PN (positive-negative) junctions) into a graphite boat, conveying the graphite boat into a film coating tube, and heating the graphite boat to 350 ℃;
(2) pre-deposition: the temperature in the furnace is kept at 350 ℃, the laughing gas is 4000sccm, the pressure is kept at 230Pa, the radio frequency power is 5000W, and the radio frequency power supply switch ratio time is 1:20, the treatment time is 1.5 minutes;
(3) depositing silicon oxide: the temperature in the furnace is kept at 500 ℃, silane is introduced at 550sccm, laughing gas is introduced at 5000sccm, the pressure is kept at 230Pa, the radio frequency power is 8000W, and the radio frequency power supply switching ratio time is 1:20, deposition time 2 minutes; the thickness of the silicon oxide film is 5 mu m;
(4) depositing silicon oxynitride: the temperature in the furnace is kept at 500 ℃, 400sccm of silane, 4000sccm of ammonia gas and 4000sccm of laughing gas are introduced, the pressure is kept at 230Pa, the radio frequency power is 12000W, the on-off ratio time of the radio frequency power supply is 1:10, and the deposition time is 7 minutes; the thickness of the silicon oxynitride film layer is 60 mu m; the refractive index of the oxynitride film was 1.83;
(5) depositing high-folding silicon nitride: keeping the temperature in the furnace at 490 ℃, introducing 1000sccm of silane and 5000sccm of ammonia gas, keeping the pressure at 230Pa, keeping the radio frequency power at 12500W, keeping the radio frequency power supply on-off ratio time at 1:10, and keeping the deposition time at 8 minutes; the thickness of the silicon nitride layer is 80 mu m; the refractive index of silicon nitride is 2.13;
(6) evacuating, back-pressing, repeatedly vacuumizing, introducing nitrogen, and replacing special gas in the tube to ensure that the tube is full of nitrogen;
(7) and (5) discharging the boat and blanking.
The laminated back film provided by the embodiment has an aluminum oxide layer, a silicon oxynitride layer and a silicon nitride layer laminated in sequence on the back surface of a silicon wafer, and a PN junction is arranged in the silicon wafer of the laminated back film.
Example 3
This example prepares a laminated back film as follows:
(1) preparing and feeding a tube, namely loading a silicon wafer (one surface of which is provided with an aluminum oxide layer with the thickness of 4 mu m after ALD (atomic layer deposition), and the silicon wafer contains PN (positive-negative) junctions) into a graphite boat, conveying the graphite boat into a film coating tube, and heating the graphite boat to 350 ℃;
(2) pre-deposition: the temperature in the furnace is kept at 350 ℃, the laughing gas is 4000sccm, the pressure is kept at 230Pa, the radio frequency power is 5000W, and the radio frequency power supply switch ratio time is 1:20, the treatment time is 1.5 minutes;
(3) depositing silicon oxide: the temperature in the furnace is kept at 500 ℃, silane is introduced at 550sccm, laughing gas is introduced at 5000sccm, the pressure is kept at 230Pa, the radio frequency power is 8000W, and the radio frequency power supply switching ratio time is 1:20, deposition time 2 minutes; the thickness of the silicon oxide film is 5 mu m;
(4) depositing silicon oxynitride: keeping the temperature in the furnace at 500 ℃, introducing 400sccm of silane, 6000sccm of ammonia gas and 2000sccm of laughing gas, keeping the pressure at 230Pa, the radio frequency power at 12000W, switching on and off the radio frequency power supply for 1:10, and depositing for 9 minutes; the thickness of the silicon oxynitride film layer is 80 mu m; the refractive index of the oxynitride film is 1.89;
(5) depositing high-folding silicon nitride: keeping the temperature in the furnace at 490 ℃, introducing 1000sccm of silane and 5000sccm of ammonia gas, keeping the pressure at 230Pa, keeping the radio frequency power at 12500W, keeping the radio frequency power supply on-off ratio time at 1:10, and keeping the deposition time at 8 minutes; the thickness of the silicon nitride layer is 80 mu m; the refractive index of silicon nitride is 2.13;
(6) evacuating, back-pressing, repeatedly vacuumizing, introducing nitrogen, and replacing special gas in the tube to ensure that the tube is full of nitrogen;
(7) and (5) discharging the boat and blanking.
The laminated back film provided by the embodiment has an aluminum oxide layer, a silicon oxynitride layer and a silicon nitride layer laminated in sequence on the back surface of a silicon wafer, and a PN junction is arranged in the silicon wafer of the laminated back film.
Example 4
This example prepares a laminated back film as follows:
(1) preparing and feeding a tube, namely loading a silicon wafer (one surface of which is provided with an aluminum oxide layer with the thickness of 4 mu m after ALD (atomic layer deposition), and the silicon wafer contains PN (positive-negative) junctions) into a graphite boat, conveying the graphite boat into a film coating tube, and heating the graphite boat to 350 ℃;
(2) pre-deposition: the temperature in the furnace is kept at 350 ℃, the laughing gas is 4000sccm, the pressure is kept at 230Pa, the radio frequency power is 5000W, and the radio frequency power supply switch ratio time is 1:20, the treatment time is 1.5 minutes;
(3) depositing silicon oxide: the temperature in the furnace is kept at 500 ℃, silane is introduced at 550sccm, laughing gas is introduced at 5000sccm, the pressure is kept at 230Pa, the radio frequency power is 8000W, and the radio frequency power supply switching ratio time is 1:20, deposition time 2 minutes; the thickness of the silicon oxide film is 5 mu m;
(4) depositing silicon oxynitride: keeping the temperature in the furnace at 500 ℃, introducing 400sccm of silane, 6000sccm of ammonia gas and 2000sccm of laughing gas, keeping the pressure at 230Pa, the radio frequency power at 12000W, switching on and off the radio frequency power supply for 1:10, and depositing for 9 minutes; the thickness of the silicon oxynitride film layer is 60 mu m; the refractive index of the oxynitride film is 1.88;
(5) depositing high-folding silicon nitride: keeping the temperature in the furnace at 490 ℃, introducing 1000sccm of silane and 5000sccm of ammonia gas, keeping the pressure at 230Pa, keeping the radio frequency power at 12500W, keeping the radio frequency power supply on-off ratio time at 1:10, and keeping the deposition time at 6 minutes; the thickness of the silicon nitride layer is 60 mu m; the refractive index of silicon nitride is 2.11;
(6) evacuating, back-pressing, repeatedly vacuumizing, introducing nitrogen, and replacing special gas in the tube to ensure that the tube is full of nitrogen;
(7) and (5) discharging the boat and blanking.
The laminated back film provided by the embodiment has an aluminum oxide layer, a silicon oxynitride layer and a silicon nitride layer laminated in sequence on the back surface of a silicon wafer, and a PN junction is arranged in the silicon wafer of the laminated back film.
Example 5
This example prepares a laminated back film as follows:
(1) preparing and feeding a tube, namely loading a silicon wafer (one surface of which is provided with an aluminum oxide layer with the thickness of 3 mu m after ALD (atomic layer deposition), and the silicon wafer contains PN (positive-negative) junctions) into a graphite boat, conveying the graphite boat into a film coating tube, and heating the graphite boat to 350 ℃;
(2) pre-deposition: the temperature in the furnace is kept at 380 ℃, the laughing gas is 2000sccm, the pressure is kept at 200Pa, the radio frequency power is 4000W, and the radio frequency power supply switch ratio time is 1:10, treatment time 2 minutes;
(3) depositing silicon oxide: the temperature in the furnace is kept at 450 ℃, 500sccm of silane and 4000sccm of laughing gas are introduced, the pressure is kept at 200Pa, the radio frequency power is 5000W, and the radio frequency power switch ratio time is 1:10, deposition time 3 minutes; the thickness of the silicon oxide film is 7 μm;
(4) depositing silicon oxynitride: keeping the temperature in the furnace at 450 ℃, introducing 500sccm of silane, 8000sccm of ammonia gas and 4000sccm of laughing gas, keeping the pressure at 200Pa, 5000W of radio frequency power, switching ratio time of a radio frequency power supply of 1:15 and deposition time of 10 minutes; the thickness of the silicon oxynitride film layer is 75 micrometers; the refractive index of the oxynitride film was 1.73;
(5) depositing high-folding silicon nitride: keeping the temperature in the furnace at 450 ℃, introducing 500sccm of silane and 7000sccm of ammonia gas, keeping the pressure at 200Pa, keeping the radio frequency power at 9000W, keeping the radio frequency power supply on-off ratio time at 1:5, and keeping the deposition time at 7 minutes; the thickness of the silicon nitride layer is 70 μm; the refractive index of silicon nitride is 2.03;
(6) evacuating, back-pressing, repeatedly vacuumizing, introducing nitrogen, and replacing special gas in the tube to ensure that the tube is full of nitrogen;
(7) and (5) discharging the boat and blanking.
The laminated back film provided by the embodiment has an aluminum oxide layer, a silicon oxynitride layer and a silicon nitride layer laminated in sequence on the back surface of a silicon wafer, and a PN junction is arranged in the silicon wafer of the laminated back film.
Example 6
This example prepares a laminated back film as follows:
(1) preparing and feeding a tube, namely loading a silicon wafer (one surface of which is provided with an aluminum oxide layer with the thickness of 3.5 mu m after ALD and contains PN junctions) into a graphite boat, conveying the graphite boat into a film coating tube, and heating to 400 ℃;
(2) pre-deposition: the temperature in the furnace is kept at 400 ℃, the laughing gas is 5000sccm, the pressure is kept at 250Pa, the radio frequency power is 8000W, and the radio frequency power supply switching ratio time is 1:10, treatment time 1.5 minutes;
(3) depositing silicon oxide: the temperature in the furnace is kept at 550 ℃, silane is introduced into the furnace at 1000sccm and laughing gas is introduced into the furnace at 7000sccm, the pressure is kept at 250Pa, the radio frequency power is 8000W, and the radio frequency power supply switching ratio time is 1:30, deposition time 4 minutes; the thickness of the silicon oxide film is 10 mu m;
(4) depositing silicon oxynitride: keeping the temperature in the furnace at 550 ℃, introducing silane 1500, ammonia gas 10000sccm, laughing gas 3000sccm, keeping the pressure at 250Pa, radio frequency power 10000W, switching ratio time of a radio frequency power supply to be 1:30, and deposition time to be 12 minutes; the thickness of the silicon oxynitride film layer is 90 mu m; the refractive index of the oxynitride film is 2.04;
(5) depositing high-folding silicon nitride: keeping the temperature in the furnace at 550 ℃, introducing 1500sccm of silane and 10000sccm of ammonia gas, keeping the pressure at 250Pa, keeping the radio frequency power at 13000W, keeping the on-off ratio time of the radio frequency power supply at 1:20, and keeping the deposition time at 5 minutes; the thickness of the silicon nitride layer is 50 μm; the refractive index of silicon nitride is 2.23;
(6) evacuating, back-pressing, repeatedly vacuumizing, introducing nitrogen, and replacing special gas in the tube to ensure that the tube is full of nitrogen;
(7) and (5) discharging the boat and blanking.
The laminated back film provided by the embodiment has an aluminum oxide layer, a silicon oxynitride layer and a silicon nitride layer laminated in sequence on the back surface of a silicon wafer, and a PN junction is arranged in the silicon wafer of the laminated back film.
Example 7
The difference between this example and example 1 is that the temperature for the pre-deposition in step (2) of this example is 450 ℃.
Example 8
The difference between this example and example 1 is that the temperature for the pre-deposition in step (2) of this example is 300 ℃.
Comparative example 1
This comparative example a laminated backsheet was prepared as follows:
(1) preparing and feeding a tube, namely loading a silicon wafer (one surface of which is provided with an aluminum oxide layer with the thickness of 3.5 mu m after ALD and contains PN junctions) into a graphite boat, conveying the graphite boat into a film coating tube, and heating to 500 ℃;
(2) and (3) depositing silicon nitride: the temperature in the furnace is kept at 490 ℃, silane is introduced at 1000sccm, ammonia gas is introduced at 10000sccm, the pressure is kept at 230Pa, the radio frequency power is 12500W, the radio frequency power switch ratio time is 1:10, and the deposition time is 15 minutes; the thickness of the silicon nitride layer is 145 μm
(3) Evacuating, back-pressing, repeatedly vacuumizing, introducing nitrogen, and replacing special gas in the tube to ensure that the tube is full of nitrogen;
(4) and (5) discharging the boat and blanking.
Comparative example 2
This comparative example a laminated backsheet was prepared as follows:
(1) preparing and feeding a tube, namely loading a silicon wafer (one surface of which is provided with an aluminum oxide layer with the thickness of 3.5 mu m after ALD and contains PN junctions) into a graphite boat, conveying the graphite boat into a film coating tube, and heating to 500 ℃;
(2) depositing silicon oxynitride: keeping the temperature in the furnace at 500 ℃, introducing 400sccm of silane, 6000sccm of ammonia gas and 2000sccm of laughing gas, keeping the pressure at 230Pa, the radio frequency power at 12000W, switching on and off the radio frequency power supply for 1:10, and depositing for 9 minutes; the thickness of the silicon oxynitride film layer is 80 mu m;
(3) and (3) depositing silicon nitride: the temperature in the furnace is kept at 490 ℃, silane is introduced at 1000sccm, ammonia gas is introduced at 10000sccm, the pressure is kept at 230Pa, the radio frequency power is 12500W, the radio frequency power switch ratio time is 1:10, and the deposition time is 15 minutes; the thickness of the silicon nitride layer is 60 μm
(4) Evacuating, back-pressing, repeatedly vacuumizing, introducing nitrogen, and replacing special gas in the tube to ensure that the tube is full of nitrogen;
(5) and (5) discharging the boat and blanking.
The test method comprises the following steps:
the laminated back film products provided by each embodiment and comparative example are prepared into the P-type single crystal PERC battery by using the same silk-screen printing line to carry out subsequent production steps, the electrical property conditions are respectively counted, and the LeTID is tested. Wherein, the test conditions of the electrical property test are that the intensity of the simulated light source is as follows: 1000w/cm 2; simulating a spectrum: AM1.5 (mass of air); and (3) testing temperature: at 25 ℃. The test conditions of the LeTID are simulated light source intensity: 400w/cm2, test temperature: at 75 ℃. The test results are given in the following table:
table 1 electrical property test results
In the table, Uoc represents the open circuit voltage; isc represents the short circuit current; rs represents a series resistor; rsh represents a parallel resistance; FF represents a fill factor; EFF stands for conversion efficiency.
As seen from the data in Table 1, the efficiency of the comparative example 1 is lower by 0.03% compared with that of the comparative example 2 after the thickness of the aluminum oxide film is reduced, mainly the open pressure is reduced, and the surface passivation effect is weakened; and compared with the embodiment 1, the efficiency is improved by the pretreatment of the aluminum oxide layer and the adjustment of the laminated back film structure. The embodiment 3 has the best efficiency, mainly the thickest film and the best passivation effect. Examples 5 and 6 increased the silica thickness, which decreased FF and decreased overall efficiency.
TABLE 2LeTID test results (test temperature 75 ℃ C.)
From the data in table 2, the LeTID phenomenon is reduced for the adjustment of the laminate backing film structure: example 4 is the most effective, the silicon nitride layer accounts for the largest proportion (about 55%) in the film layer, and the hydrogen content in the cell is the least; examples 1 and 2 had the same film structure, but the LeTID data for example 2 was small because the ammonia usage in example 2 was lower than in example 1.
It can be seen from the above examples and comparative examples that in example 1, after the aluminum oxide layer is formed on the silicon wafer ALD, an optimized aluminum oxide layer is pre-deposited, a silicon oxide layer is deposited, a silicon oxynitride film is coated thereon, and a high refractive index silicon nitride film is coated thereon. Example 2 the flow ratio of the silicon oxynitride film was adjusted based on example 1. Example 3 the thickness of the silicon oxynitride film was adjusted based on example 1. Example 4 the thickness of the silicon nitride film layer was adjusted based on example 1. In the embodiments 1 to 6, the surface of the aluminum oxide is pretreated by the gas containing O, so that the surface negative charge density and the passivation effect can be enhanced, and the passivation effect of the back film can be enhanced by the silicon oxynitride film layer; the back silicon oxide layer and the silicon oxynitride layer are superposed with the silicon nitride layer to replace a single-layer silicon nitride film layer in the prior art, so that the use amount of hydrogen-containing source gases (ammonia gas and the like) is reduced, the atomic weight of hydrogen in the battery is reduced, and the LeTID phenomenon of the battery piece is improved.
Example 7 because the pre-deposition temperature is higher, the alumina is damaged, the passivation effect is weakened, and the efficiency is reduced.
Example 8 because the pre-deposition temperature is lower, the effect of oxygen atoms ionized from laughing gas to repair the aluminum oxide layer is poor, and the efficiency is reduced.
Comparative example 1 the overall efficiency was lowest and the LeTID was severe because the alumina layer thickness decreased and the subsequent stack was a single layer of silicon nitride.
Comparative example 2 the aluminum oxide layer thickness was decreased compared to the other examples, resulting in a weak overall passivation effect, and the pretreatment layer (step 1) and the silicon oxide layer were not present, resulting in still lower efficiency than the other examples, and a poor LeTID.
The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (10)
1. A method of making a laminated back film, comprising the steps of:
(1) placing a silicon wafer with an aluminum oxide layer deposited on one surface in a reactor, vacuumizing, and introducing first gas to perform pre-deposition on the aluminum oxide layer to obtain a first semi-finished product; the first gas is an oxygen-containing gas;
(2) introducing a second gas, and depositing a silicon oxide layer on the aluminum oxide layer of the pretreated product in the step (1) to obtain a second semi-finished product;
(3) introducing a third gas, and depositing a silicon oxynitride layer on the silicon oxide layer of the second semi-finished product in the step (2) to obtain a third semi-finished product;
(4) and (4) introducing fourth gas, and depositing a silicon nitride layer on the silicon oxynitride layer of the third semi-finished product in the step (3) to obtain the laminated back film.
2. The method of claim 1, wherein the step (1) of placing in a reactor comprises: loading a silicon wafer with an aluminum oxide layer deposited on one surface into a graphite boat, and then placing the graphite boat into a reactor;
preferably, the thickness of the aluminum oxide layer of the silicon wafer with the aluminum oxide layer deposited on one surface in the step (1) is 3-4 μm;
preferably, a PN junction is arranged in the silicon wafer with the aluminum oxide layer deposited on one surface in the step (1).
3. The production method according to claim 1 or 2, wherein the first gas of step (1) comprises laughing gas;
preferably, the flow rate of the first gas in the step (1) is 2000-;
preferably, the temperature of the pre-deposition in the step (1) is 350-400 ℃;
preferably, the RF power for the pre-deposition in the step (1) is 4000-;
preferably, the duty cycle of the pre-deposition of step (1) is 1: (10-30);
preferably, the pressure of the pre-deposition reactor in the step (1) is 200-250 Pa.
4. The production method according to any one of claims 1 to 3, wherein the second gas in step (2) comprises laughing gas and silane;
preferably, in the second gas, the laughing gas flow rate is 4000-7000sccm, and the silane flow rate is 500-1000 sccm;
preferably, the temperature of the deposition in the step (2) is 450-550 ℃;
preferably, the RF power of the deposition in the step (2) is 5000-;
preferably, the duty cycle of the deposition of step (2) is 1: (10-30);
preferably, the pressure of the reactor for deposition in the step (2) is 200-250 Pa;
preferably, the thickness of the silicon oxide layer obtained by deposition in the step (2) is 5-10 μm.
5. The production method according to any one of claims 1 to 4, wherein the third gas in step (3) comprises laughing gas, silane, and ammonia gas;
preferably, in the third gas, the laughing gas flow rate is 1500-;
preferably, the deposition temperature in step (3) is 450-550 ℃;
preferably, the RF power for the deposition in step (3) is 5000-;
preferably, the duty cycle of the deposition of step (3) is 1: (10-30);
preferably, the pressure of the reactor for deposition in the step (3) is 200-250 Pa;
preferably, the thickness of the silicon oxynitride layer obtained by deposition in the step (3) is 60-90 μm;
preferably, the refractive index of the silicon oxynitride layer deposited in the step (3) is 1.85-2.0.
6. The production method according to any one of claims 1 to 5, wherein the fourth gas in the step (4) comprises silane and ammonia;
preferably, the flow rate of silane in the fourth gas is 500-;
preferably, the deposition temperature in step (4) is 450-550 ℃;
preferably, the RF power of the deposition in the step (4) is 9000-;
preferably, the duty cycle of the deposition of step (4) is 1: (5-20);
preferably, the pressure of the reactor for deposition in the step (4) is 200-250 Pa;
preferably, the thickness of the silicon nitride layer obtained by the deposition in the step (4) is 50-80 μm;
preferably, the refractive index of the silicon nitride layer obtained by the deposition in the step (4) is 2.0-2.1.
7. The method of any one of claims 1-6, further comprising: after the silicon nitride layer is deposited, repeatedly carrying out operations of vacuumizing and introducing protective gas, and then taking out a product;
preferably, the protective gas comprises nitrogen and/or argon.
8. The method for preparing according to any one of claims 1 to 7, characterized in that it comprises the steps of:
(1) loading a silicon wafer with an aluminum oxide layer deposited on one surface into a graphite boat, then placing the graphite boat into a reactor, vacuumizing, and introducing first gas to pre-deposit the aluminum oxide layer to obtain a first semi-finished product; the first gas is an oxygen-containing gas; the first gas comprises laughing gas, and the flow rate of the laughing gas is 2000-; the temperature of the pre-deposition is 350-400 ℃; the pre-deposition radio frequency power is 4000-; duty cycle of predeposition is 1: (10-30); the pressure of the pre-deposition reactor is 200-250 Pa;
(2) introducing a second gas, and depositing a silicon oxide layer on the aluminum oxide layer of the pretreated product in the step (1) to obtain a second semi-finished product; the second gas comprises laughing gas and silane, wherein the flow rate of the laughing gas is 4000-7000sccm, and the flow rate of the silane is 500-1000 sccm; the deposition temperature in the step (2) is 450-: (10-30), the pressure of the deposition reactor is 200-250 Pa;
(3) introducing a third gas, and depositing a silicon oxynitride layer on the silicon oxide layer of the second semi-finished product in the step (2) to obtain a third semi-finished product; the third gas comprises laughing gas, silane and ammonia gas, wherein the flow rate of the laughing gas is 1500-; the deposition temperature in the step (3) is 450-: (10-30), the pressure of the deposition reactor is 200-250 Pa;
(4) introducing fourth gas, depositing a silicon nitride layer on the silicon oxynitride layer of the third semi-finished product in the step (3), repeatedly vacuumizing and introducing protective gas, and taking out the graphite boat to obtain the laminated back film; the fourth gas comprises silane and ammonia, the flow rate of the silane is 500-; the deposition temperature in the step (4) is 450-: (5-20), the pressure of the deposition reactor is 200-250 Pa.
9. A laminated backing film prepared according to the method of any one of claims 1 to 8.
10. The laminated back film of claim 9, wherein an aluminum oxide layer, a silicon oxynitride layer, and a silicon nitride layer are sequentially laminated on the silicon wafer back surface of the laminated back film;
preferably, a PN junction is arranged in the silicon wafer of the laminated back film.
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