CN110911271A - Rework process of monocrystalline silicon battery piece - Google Patents
Rework process of monocrystalline silicon battery piece Download PDFInfo
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- CN110911271A CN110911271A CN201911269361.5A CN201911269361A CN110911271A CN 110911271 A CN110911271 A CN 110911271A CN 201911269361 A CN201911269361 A CN 201911269361A CN 110911271 A CN110911271 A CN 110911271A
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- 238000000034 method Methods 0.000 title claims abstract description 58
- 229910021421 monocrystalline silicon Inorganic materials 0.000 title claims abstract description 24
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims abstract description 178
- 239000000243 solution Substances 0.000 claims abstract description 100
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 85
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 85
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 74
- 239000011259 mixed solution Substances 0.000 claims abstract description 59
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 39
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- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims abstract description 30
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 26
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000012535 impurity Substances 0.000 claims abstract description 20
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 16
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 38
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- ZEFWRWWINDLIIV-UHFFFAOYSA-N tetrafluorosilane;dihydrofluoride Chemical compound F.F.F[Si](F)(F)F ZEFWRWWINDLIIV-UHFFFAOYSA-N 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic System
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02002—Preparing wafers
- H01L21/02005—Preparing bulk and homogeneous wafers
- H01L21/02008—Multistep processes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02002—Preparing wafers
- H01L21/02005—Preparing bulk and homogeneous wafers
- H01L21/02008—Multistep processes
- H01L21/0201—Specific process step
- H01L21/02019—Chemical etching
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02002—Preparing wafers
- H01L21/02005—Preparing bulk and homogeneous wafers
- H01L21/02032—Preparing bulk and homogeneous wafers by reclaiming or re-processing
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
The embodiment of the invention relates to a rework process of a monocrystalline silicon battery piece. The process comprises the following steps: removing aluminum paste, an oxide film and a silicon nitride film on the front and back surfaces of the cell simultaneously by using a mixed solution of hydrochloric acid and hydrofluoric acid; removing residual silver paste by using a nitric acid solution; and removing impurities on the surface of the silicon wafer of the cell slice by using a mixed solution of nitric acid and hydrofluoric acid. The invention improves the EL yield of the reworked cell, reduces the reworking steps of the cell and reduces the breakage rate of the monocrystalline silicon cell in the reworking process.
Description
Technical Field
The embodiment of the invention relates to the technical field of solar cells, in particular to a reworking process of a monocrystalline silicon cell.
Background
The production process of the monocrystalline silicon battery piece mainly comprises the steps of wool making and acid washing, diffusion and laser SE, etching and back polishing, oxidation and front and back surface coating, laser grooving, screen printing, sintering, electric injection or light injection, testing and sorting. In these processes, a certain proportion of the finished battery pieces with grade C are not good, and these grade C battery pieces are sold at low price, resulting in waste of resources.
In the related art, the C-level cells are reworked and reduced to be the original silicon wafer and then are reprocessed. With regard to the above technical solutions, the inventors have found that at least some of the following technical problems exist: for example, the existing rework process causes a large amount of chipping phenomena in the reduction process of a single crystal PERC cell with a double-sided plated film, and in addition, due to the characteristic of the double-sided plated film of the single crystal PERC cell, the silicon wafer is prevented from further reacting with alkali in the rework process, so that an alloy layer and impurities are more difficult to remove, and EL (electroluminescence) defects and the like are easy to occur. Accordingly, there is a need to ameliorate one or more of the problems with the related art solutions described above.
It is noted that this section is intended to provide a background or context to the embodiments of the invention that are recited in the claims. The description herein is not admitted to be prior art by inclusion in this section.
Disclosure of Invention
An object of the embodiments of the present invention is to provide a rework process of a single crystal silicon battery piece, so as to overcome one or more problems caused by the limitations and disadvantages of the related art at least to a certain extent.
The rework process of the monocrystalline silicon battery piece provided by the embodiment of the invention comprises the following steps:
removing aluminum paste, an oxide film and a silicon nitride film on the front and back surfaces of the cell simultaneously by using a mixed solution of hydrochloric acid and hydrofluoric acid;
removing residual silver paste by using a nitric acid solution;
and removing impurities on the surface of the silicon wafer of the cell slice by using a mixed solution of nitric acid and hydrofluoric acid.
In an embodiment of the present invention, the step of simultaneously removing the aluminum paste, the oxide film and the silicon nitride film on the front and back surfaces of the cell by using the mixed solution of hydrochloric acid and hydrofluoric acid includes:
uniformly mixing a hydrochloric acid solution, a hydrofluoric acid solution and water in a volume ratio of 1-3:1-3:14-18 to obtain a mixed solution of hydrochloric acid and hydrofluoric acid, wherein the concentration of the hydrochloric acid solution is 35-38%, and the concentration of the hydrofluoric acid solution is 48.5-49.5%;
and soaking the battery piece in the mixed solution of the hydrochloric acid and the hydrofluoric acid.
In an embodiment of the invention, in the step of immersing the battery piece in the mixed solution of hydrochloric acid and hydrofluoric acid, the immersion time is 600-1800 seconds.
In an embodiment of the present invention, the step of removing the residual silver paste with the nitric acid solution includes:
uniformly mixing a concentrated nitric acid solution and water in a volume ratio of 1-5:25-33 to obtain a nitric acid solution, wherein the concentration of the concentrated nitric acid solution is 65-68%.
And soaking the cell piece with the aluminum paste, the oxide film and the silicon nitride film removed in the nitric acid solution.
In an embodiment of the invention, in the step of soaking the cell with the aluminum paste, the oxide film and the silicon nitride film removed in the nitric acid solution, the soaking time is 300-1500 s.
In an embodiment of the invention, in the step of soaking the cell without the aluminum paste, the oxide film and the silicon nitride film in the nitric acid solution, the soaking temperature is 40-70 ℃.
In an embodiment of the present invention, the step of removing impurities on the surface of the silicon wafer of the battery piece by using a mixed solution of nitric acid and hydrofluoric acid includes:
uniformly mixing a concentrated nitric acid solution, a hydrofluoric acid solution and water in a volume ratio of 1-3:4-12:5-15 to obtain a mixed solution of nitric acid and hydrofluoric acid, wherein the concentration of the concentrated nitric acid solution is 65-68%, and the concentration of the hydrofluoric acid solution is 48.5-49.5%;
and soaking the battery piece in the mixed solution of the nitric acid and the hydrofluoric acid.
In an embodiment of the invention, in the step of immersing the battery piece in the mixed solution of nitric acid and hydrofluoric acid, the immersion time is 50-150 seconds.
In an embodiment of the invention, in the step of immersing the battery piece in the mixed solution of nitric acid and hydrofluoric acid, the immersion temperature is 7-13 DEG C
In an embodiment of the invention, after the step of immersing the battery piece in the mixed solution of nitric acid and hydrofluoric acid, the method further comprises the step of producing the battery piece according to an alkaline texturing process.
The technical scheme provided by the embodiment of the invention can have the following beneficial effects:
in the embodiment of the invention, hydrochloric acid and hydrofluoric acid can react with aluminum, and hydrofluoric acid can react with silicon oxide, aluminum oxide and silicon nitride, and the two solutions are mixed, so that the reaction effect is not influenced, aluminum paste, an oxide film and a silicon nitride film on the front surface and the back surface of the cell can be removed simultaneously, the reworking steps of the cell are reduced, and compared with the method of simply using hydrofluoric acid solution, the method for removing the aluminum paste by using the mixed solution of hydrochloric acid and hydrofluoric acid reduces the treatment capacity of F ions in waste liquid; secondly, silver paste remained on the silicon chip of the cell can be thoroughly removed by using a nitric acid solution; and finally, removing the rest impurities on the silicon wafer of the cell by using the corrosion effect of the mixed solution of nitric acid and hydrofluoric acid, so that the cell is recovered to be in a pure state. On one hand, the method disclosed by the invention is treated by using an acidic solution, so that impurity metal ions caused by the use of an alkaline solution are avoided, and the removal of impurities and an alloy layer is more thorough, so that the finally obtained silicon wafer is purer, and the EL yield of the reworked cell is improved to a certain extent; on the other hand, the invention reduces the rework steps of the cell, improves the rework efficiency, and simultaneously reduces the breakage rate of the monocrystalline silicon cell in the rework process to a certain extent.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure. It is to be understood that the drawings in the following description are merely exemplary of the disclosure, and that other drawings may be derived from those drawings by one of ordinary skill in the art without the exercise of inventive faculty.
Fig. 1 shows a flow chart of a rework process of a single crystal silicon cell piece in an exemplary embodiment of the invention.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
With the development of the industry, the single-crystal PERC and the N-type PERT high-efficiency battery with the double-sided coating has basically replaced the conventional single-crystal battery with the single-sided coating. The double-sided coating is to plate a silicon nitride film on the front surface of a P-type silicon wafer and a composite film of aluminum oxide and silicon nitride on the back surface of the P-type silicon wafer, wherein the front surface and the back surface of an N-type silicon wafer are opposite to the P-type silicon wafer, or the composite film of aluminum oxide and silicon nitride is uniformly plated on the front surface and the back surface of the silicon wafer by adopting a process of combining silicon dioxide, silicon nitride and the like. In the rework process of the battery piece, due to the double-sided coating, after the aluminum paste is removed, the coating layer can prevent the silicon wafer from further reacting with alkali, so that the alloy layer and residual impurities on the battery piece are more difficult to completely remove.
In addition, single crystal PERC and N-type PERT cells have higher requirements for cleanliness, contamination sources, impurities, etc. than conventional single crystal cells, and poor EL may be caused by a few defects occurring in any step after the time returns. EL inspection, a common method used to inspect crystalline silicon solar cells for defects. As for the PERC battery, the PERC battery is the most different from a conventional battery in the passivation of a back surface dielectric film, and the PERC battery adopts local metal contact, so that the back surface recombination rate is greatly reduced, the light reflection of the back surface is improved, and the conversion efficiency is greatly improved. Just because of the significant decrease in the recombination rate of the back surface, very small impurities and defects of the back surface are shaded under the EL test, and the EL is considered to be poor.
On the other hand, for the single crystal PERC battery, in order to realize good contact of the back surface, a laser grooving process is generally used in the manufacturing process, the laser process can cause certain damage to the silicon wafer, and during rework, the problems that the more process links are, the more fragments are easy to break exist.
Based on this, the present exemplary embodiment provides a rework process of a single crystal silicon cell piece, as shown with reference to fig. 1, the process including the steps of:
step S101: removing aluminum paste, an oxide film and a silicon nitride film on the front and back surfaces of the cell simultaneously by using a mixed solution of hydrochloric acid and hydrofluoric acid;
step S102: removing residual silver paste by using a nitric acid solution;
step S103: and removing impurities on the surface of the silicon wafer of the cell slice by using a mixed solution of nitric acid and hydrofluoric acid.
In the embodiment of the invention, hydrochloric acid and hydrofluoric acid can react with aluminum, and hydrofluoric acid can react with silicon oxide, aluminum oxide and silicon nitride, and the two solutions are mixed, so that the reaction effect is not influenced, aluminum paste, an oxide film and a silicon nitride film on the front surface and the back surface of the cell can be removed simultaneously, the reworking steps of the cell are reduced, and compared with the method of simply using hydrofluoric acid solution, the treatment amount of fluoride ions in waste liquid is reduced by using the mixed solution of hydrochloric acid and hydrofluoric acid to remove the aluminum paste; secondly, in the previous step, the silver paste attached to the oxide film and the silicon nitride film can fall off along with the reaction of the oxide film, the silicon nitride film and hydrofluoric acid, but some residual silver paste exists on the silicon wafer, and the residual silver paste on the silicon wafer of the cell can be completely removed by using a nitric acid solution; and finally, removing the rest impurities on the silicon wafer of the cell by using the corrosion effect of the mixed solution of nitric acid and hydrofluoric acid, so that the cell is recovered to be in a pure state. On one hand, the method disclosed by the invention is treated by using an acidic solution, so that impurity metal ions caused by the use of an alkaline solution are avoided, and the removal of impurities and an alloy layer is more thorough, so that the finally obtained silicon wafer is purer, and the EL yield of the reworked cell is improved to a certain extent; on the other hand, the invention reduces the rework steps of the cell, improves the rework efficiency, and simultaneously reduces the breakage rate of the monocrystalline silicon cell in the rework process to a certain extent.
Next, each step of the above-described method in the present exemplary embodiment will be described in more detail.
In one embodiment, the battery cell mentioned in step S101 is a finished battery cell with poor C-level, and specifically, step S101 further includes the following steps:
step S1011: uniformly mixing a hydrochloric acid solution, a hydrofluoric acid solution and water in a volume ratio of 1-3:1-3:14-18 to obtain a mixed solution of hydrochloric acid and hydrofluoric acid, wherein the concentration of the hydrochloric acid solution is 35-38%, and the concentration of the hydrofluoric acid solution is 48.5-49.5%;
step S1012: and soaking the battery piece in a mixed solution of hydrochloric acid and hydrofluoric acid.
Hydrofluoric acid itself is a weak acid and is very corrosive, and the corrosivity of hydrofluoric acid is due to fluoride ions, HF ═ H﹢+F﹣The radius of the fluorine ions in hydrofluoric acid is small, even smaller than that of oxygen ions, which results in strong permeability.
The removal of the aluminum paste, the oxide film and the silicon nitride film on the front and back surfaces of the single crystal PERC cell can also be performed separately, for example, by removing the aluminum paste with hydrochloric acid and then removing the oxide film and the silicon nitride film with hydrofluoric acid, or by removing the aluminum paste, the oxide film and the silicon nitride film with pure hydrofluoric acid solution.
However, when the aluminum paste is removed by hydrochloric acid and then the oxide film and the silicon nitride film are removed by hydrofluoric acid, the solution is washed with water each time, and the procedures are multiple, and time and labor are wasted. When the hydrofluoric acid is used alone to remove aluminum paste, oxide films and silicon nitride films on the front and back surfaces of the cell, the amount of the hydrofluoric acid needed is large, the amount of introduced fluorine ions is high, the reaction time is difficult to control, and the waste liquid is difficult to treat.
According to the invention, after hydrofluoric acid and hydrochloric acid are mixed, two steps which are originally separately performed are changed into a step of reducing the rework of the battery piece, meanwhile, the addition of hydrochloric acid reduces the concentration of fluorine ions in the waste liquid, namely, the corrosivity of hydrofluoric acid is reduced, the difficulty of waste liquid treatment is reduced, and the optimal balance point is selected by adjusting the concentration of the mixed solution, so that the optimal treatment effect is achieved.
Experiments show that more than 98% of mixed film layers consisting of aluminum paste, oxide films and silicon nitride films can be removed by soaking the battery piece into mixed liquid consisting of 35-38% hydrochloric acid solution, 48.5-49.5% hydrofluoric acid solution and water in a volume ratio of 1-3:1-3: 14-18.
Preferably, the battery piece is soaked in the mixed solution of hydrochloric acid and hydrofluoric acid for 600-1800 s, and the temperature of the mixed solution is kept at normal temperature.
After step S1012 is completed, the battery piece should be taken out from the mixed solution of hydrochloric acid and hydrofluoric acid, and washed with water for 30-60S, and then the next step is performed.
In one embodiment, step S102 further comprises the steps of:
step S1021: uniformly mixing a concentrated nitric acid solution and water in a volume ratio of 1-5:25-33 to obtain a nitric acid solution, wherein the concentration of the concentrated nitric acid solution is 65-68%;
step S1022: and (4) soaking the cell piece with the aluminum paste, the oxide film and the silicon nitride film removed in a nitric acid solution.
In the reaction process of step S101, the removal of the mixed film layer is accompanied by the detachment of the silver paste partially adhering to the oxide film and the silicon nitride film, but the silver paste on the silicon wafer is not completely removed. Even if the concentration of hydrofluoric acid in step S101 is increased, the silver paste is not completely removed, but the reaction rate is increased, which is very likely to cause chipping, and is not favorable for operation. Therefore, nitric acid can be used for reacting with silver, and then residual silver paste is removed.
Experiments prove that the nitric acid solution obtained by uniformly mixing the concentrated nitric acid solution with the concentration of 65-68% and water in the volume ratio of 1-5:25-33 reduces the concentration of nitric acid, is more convenient to control the reaction speed, has low reaction degree and reduces the probability of fragment breakage.
Preferably, when the cell piece is placed into a nitric acid solution for soaking, the soaking temperature can be kept at 40-70 ℃, and the reaction speed can be accelerated by heating the nitric acid solution.
Through experiments, the residual silver paste can be completely removed by putting the cell into a nitric acid solution and soaking for 300-1500 s.
After the step S1022 is completed, the cell should be taken out of the nitric acid solution, washed with water for 30-60S, and then carried out to the next step.
In one embodiment, step S103 further comprises the steps of:
step S1031: uniformly mixing a concentrated nitric acid solution, a hydrofluoric acid solution and water in a volume ratio of 1-3:4-12:5-15 to obtain a mixed solution of nitric acid and hydrofluoric acid, wherein the concentration of the concentrated nitric acid solution is 65-68%, and the concentration of the hydrofluoric acid solution is 48.5-49.5%;
step S1032: and soaking the cell in a mixed solution of nitric acid and hydrofluoric acid.
After the steps S101 and S102, the cell pieces have been reduced into silicon pieces, but some impurities and alloys remain on the silicon pieces. The mixed solution of nitric acid and hydrofluoric acid has strong acidity, strong oxidizing property and strong corrosivity, and reacts with silicon to form Si +4HNO3+6HF＝＝H2SiF6+4NO2Therefore, impurities and alloys remaining on the silicon wafer are removed as the silicon is corroded in the presence of the ions ↓ +4H 2O. In addition, the mixed solution of nitric acid and hydrofluoric acid can also eliminate the influence of laser grooving on the texturing link in the subsequent reworking process during the manufacturing of the single crystal PERC battery.
Experiments show that the reaction time can be well controlled by soaking the cell in a mixed solution consisting of 65-68% concentrated nitric acid solution, 48.5-49.5% hydrofluoric acid solution and water in a volume ratio of 1-3:4-12:5-15, so that the cell can not be cracked due to too fast operation, or the reaction time is too long, and the thickness of the silicon wafer is greatly reduced.
Preferably, when the cell is placed into a mixed solution of nitric acid and hydrofluoric acid for soaking, the temperature of the mixed solution is kept at 7-13 ℃, and the phenomenon that the cell is broken due to too high temperature and violent reaction is avoided.
Specifically, the soaking time of the cell in the mixed solution of nitric acid and hydrofluoric acid can be controlled within 50-150 s, so that the thickness of the silicon wafer is kept to be 1-10 mu m optimally.
After step S1032 is completed, the cell should be taken out from the mixed solution of nitric acid and hydrofluoric acid, washed with water, and dried for use.
In an embodiment, after step S103, step S104 is further included, and the battery piece after the above steps is produced according to an alkali texturing process, and the specific operation process of the process may refer to the prior art, and is not described in detail herein.
According to the invention, the hydrochloric acid solution, the hydrofluoric acid solution and the concentrated nitric acid solution for preparing the mixed solution are purchased from the market, the concentration of the purchased hydrochloric acid solution is 35-38%, the concentration of the purchased hydrofluoric acid solution is 48.5-49.5%, and the concentration of the purchased concentrated nitric acid solution is 65-68%.
Detailed description of the preferred embodiment 1
Taking the finished product single crystal PERC grade cell of 156.75 × 156.75 such as non-subfissure, perforation, concentric circle and the like as an example, the method is processed according to the following reworking process steps:
soaking the battery piece in a mixed solution of 35-38% hydrochloric acid solution, 48.5-49.5% hydrofluoric acid solution and water in a volume ratio of 1:3:14 for 600s, and washing with water for 30 s;
soaking the cell piece in a nitric acid solution formed by mixing 65-68% concentrated nitric acid solution and water in a ratio of 1:33 for 1500 seconds, keeping the temperature of the nitric acid solution at 40 ℃, and then washing the cell piece with water for 30 seconds;
soaking the cell piece in a mixed solution of 65-68% concentrated nitric acid solution, 48.5-49.5% hydrofluoric acid solution and water in a volume ratio of 3:4:15 for 50s, keeping the temperature of the mixed solution of nitric acid and hydrofluoric acid at 7 ℃, and then washing and drying;
and (3) producing the silicon wafer after washing and drying according to an alkali texturing process, and re-preparing the silicon wafer into a single crystal PERC battery piece, wherein the EL yield is 90%, and the fragment rate is 1.5%.
Specific example 2
Taking the finished product single crystal PERC grade cell of 156.75 × 156.75 such as non-subfissure, perforation, concentric circle and the like as an example, the method is processed according to the following reworking process steps:
soaking the battery piece in a mixed solution of 35-38% hydrochloric acid solution, 48.5-49.5% hydrofluoric acid solution and water in a volume ratio of 3:2:18 for 1800 seconds, and washing the battery piece with water for 60 seconds;
soaking the cell piece in a nitric acid solution formed by mixing 65-68% concentrated nitric acid solution and water in a ratio of 1:5 for 300s, keeping the temperature of the nitric acid solution at 70 ℃, and then washing the cell piece with water for 60 s;
soaking the cell piece in a mixed solution of 65-68% concentrated nitric acid solution, 48.5-49.5% hydrofluoric acid solution and water in a volume ratio of 1:12:15 for 150s, keeping the temperature of the mixed solution of nitric acid and hydrofluoric acid at 13 ℃, and then washing and drying with water;
and (3) producing the silicon wafer after washing and drying according to an alkali texturing process, and re-preparing the silicon wafer into a single crystal PERC battery piece, wherein the EL yield is 94% and the fragment rate is 1.8%.
Specific example 3
Taking a finished product single crystal N-type PERT non-subfissure, perforation, concentric circle and other C-grade cell pieces of 156.75 × 156.75 as an example, the processing is carried out according to the following reworking process steps:
soaking the cell piece in a mixed solution of 35-38% hydrochloric acid solution, 48.5-49.5% hydrofluoric acid solution and water in a volume ratio of 2:1:15 for 1000s, and washing with water for 50 s;
soaking the cell piece in an acid solution formed by mixing 65-68% concentrated nitric acid solution and water in a ratio of 1:10 for 700s, keeping the temperature of the nitric acid solution at 50 ℃, and then washing the cell piece with water for 60 s;
soaking the cell piece in a mixed solution of 65-68% concentrated nitric acid solution, 48.5-49.5% hydrofluoric acid solution and water in a volume ratio of 2:10:10 for 110s, keeping the temperature of the mixed solution of nitric acid and hydrofluoric acid at 10 ℃, and then washing and drying with water;
and (3) producing the silicon wafer after washing and drying according to an alkali texturing process, and re-preparing the silicon wafer into a single crystal N-type PERT battery piece, wherein the EL yield is 93%, and the fragment rate is 1.1%.
Specific example 4
Taking the finished product single crystal of 156.75 × 156.75, such as C-grade cell slices with non-subfissure, perforation, concentric circles and the like as an example, the processing is carried out according to the following reworking process steps:
soaking the cell piece in a mixed solution of 35-38% hydrochloric acid solution, 48.5-49.5% hydrofluoric acid solution and water in a volume ratio of 3:3:16 for 1300s, and washing with water for 40 s;
soaking the cell piece in a nitric acid solution formed by mixing 65-68% of concentrated nitric acid solution and water in a ratio of 1:15 for 1200s, keeping the temperature of the nitric acid solution at 60 ℃, and then washing the cell piece with water for 60 s;
soaking the cell piece in a mixed solution of 65-68% concentrated nitric acid solution, 48.5-49.5% hydrofluoric acid solution and water in a volume ratio of 3:5:5 for 70s, keeping the temperature of the mixed solution of nitric acid and hydrofluoric acid at 12 ℃, and then washing and drying;
and (3) producing the silicon wafer after washing and drying according to an alkali texturing process, and re-preparing the silicon wafer into a single crystal battery piece, wherein the EL yield is 96%, and the fragment rate is 1.0%.
According to the monocrystalline silicon cell rework process provided by the invention, the acidic solution is used for treatment, so that impurity metal ions caused by the use of an alkaline solution are avoided, and the removal of impurities and an alloy layer is more thorough, so that the finally obtained silicon wafer is purer, and the EL yield of the reworked cell is improved to a certain extent; on the other hand, the invention reduces the rework steps of the cell, improves the rework efficiency, and simultaneously reduces the breakage rate of the monocrystalline silicon cell in the rework process to a certain extent.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples described in this specification can be combined and combined by those skilled in the art.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
Claims (10)
1. A rework process of a monocrystalline silicon battery piece is characterized by comprising the following steps:
removing aluminum paste, an oxide film and a silicon nitride film on the front and back surfaces of the cell simultaneously by using a mixed solution of hydrochloric acid and hydrofluoric acid;
removing residual silver paste by using a nitric acid solution;
and removing impurities on the surface of the silicon wafer of the cell slice by using a mixed solution of nitric acid and hydrofluoric acid.
2. The process for reworking a single-crystal silicon cell according to claim 1, wherein the step of simultaneously removing the aluminum paste, the oxide film and the silicon nitride film on the front and back surfaces of the cell using a mixed solution of hydrochloric acid and hydrofluoric acid comprises:
uniformly mixing a hydrochloric acid solution, a hydrofluoric acid solution and water in a volume ratio of 1-3:1-3:14-18 to obtain a mixed solution of hydrochloric acid and hydrofluoric acid, wherein the concentration of the hydrochloric acid solution is 35-38%, and the concentration of the hydrofluoric acid solution is 48.5-49.5%;
and soaking the battery piece in the mixed solution of the hydrochloric acid and the hydrofluoric acid.
3. The rework process of the single crystal silicon cell piece according to claim 2, wherein in the step of immersing the cell piece in the mixed solution of hydrochloric acid and hydrofluoric acid, the immersion time is 600-1800 s.
4. The rework process of single crystal silicon cell piece of claim 1, wherein the step of removing residual silver paste with nitric acid solution comprises:
uniformly mixing a concentrated nitric acid solution and water in a volume ratio of 1-5:25-33 to obtain a nitric acid solution, wherein the concentration of the concentrated nitric acid solution is 65-68%;
and soaking the cell piece with the aluminum paste, the oxide film and the silicon nitride film removed in the nitric acid solution.
5. The rework process of the single crystal silicon cell slice of claim 4, wherein in the step of soaking the cell slice with the aluminum paste, the oxide film and the silicon nitride film removed in a nitric acid solution, the soaking time is 300-1500 s.
6. The rework process of the single crystal silicon cell piece according to claim 4, wherein in the step of immersing the cell piece from which the aluminum paste, the oxide film and the silicon nitride film are removed in a nitric acid solution, the immersion temperature is 40-70 ℃.
7. The rework process of the single crystal silicon cell as claimed in claim 1, wherein the step of removing impurities on the surface of the silicon wafer of the cell with a mixture of nitric acid and hydrofluoric acid comprises:
uniformly mixing a concentrated nitric acid solution, a hydrofluoric acid solution and water in a volume ratio of 1-3:4-12:5-15 to obtain a mixed solution of nitric acid and hydrofluoric acid, wherein the concentration of the concentrated nitric acid solution is 65-68%, and the concentration of the hydrofluoric acid solution is 48.5-49.5%;
and soaking the battery piece in the mixed solution of the nitric acid and the hydrofluoric acid.
8. The rework process of the single crystal silicon cell slice of claim 7, wherein in the step of immersing the cell slice in the mixed solution of nitric acid and hydrofluoric acid, the immersion time is 50-150 s.
9. The rework process of the single crystal silicon cell piece according to claim 7, wherein in the step of immersing the cell piece in the mixed solution of nitric acid and hydrofluoric acid, the immersion temperature is 7-13 ℃.
10. The rework process of the single crystal silicon cell piece of claim 1, further comprising producing the cell piece according to an alkaline texturing process after the step of immersing the cell piece in the mixed solution of nitric acid and hydrofluoric acid.
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| CN117174573A (en) * | 2023-11-03 | 2023-12-05 | 山东有研艾斯半导体材料有限公司 | Method for removing aluminum metal film on surface of wafer |
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