CN114059037B - Method for solving EL center dark spot of PERC battery, PERC battery and application thereof - Google Patents
Method for solving EL center dark spot of PERC battery, PERC battery and application thereof Download PDFInfo
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- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims abstract description 22
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- 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
- C23C16/02—Pretreatment of the material to be coated
- C23C16/0227—Pretreatment of the material to be coated by cleaning or etching
- C23C16/0245—Pretreatment of the material to be coated by cleaning or etching by etching with a plasma
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- 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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- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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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
- C23C16/403—Oxides of aluminium, magnesium or beryllium
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- 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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Abstract
The invention provides a method for solving the problem of dark spots at the center of a PERC battery EL, a PERC battery and application thereof, wherein the method comprises the steps of sequentially coating and sintering; the coating method comprises the following steps: introducing laughing gas under radio frequency power to pretreat the silicon wafer, keeping the pressure constant after the silicon wafer is pretreated, and then sequentially depositing aluminum oxide and silicon nitride; the sintering comprises the following steps: the high-temperature main burning zone adopts a three-peak curve sintering mode, and the peak temperature is 775-785 ℃. The invention solves the problem of the EL center dark spot of the PERC battery by improving the coating and sintering processes in the preparation process of the PERC battery. The laughing gas ionized into plasma is adopted to ensure the high cleanliness of the growth substrate of the passive film; the density of the aluminum oxide is improved by improving a method for coating a film on a silicon wafer; by adjusting the sintering process, the damage of the back membrane caused by temperature mutation is avoided, and the problem of chapping of local loose alumina after high-temperature sintering is solved.
Description
Technical Field
The invention belongs to the field of crystalline silicon solar PERC (Positive emitter resistance) batteries, relates to a method for solving EL (electroluminescence) center dark spots, and particularly relates to a method for solving the EL center dark spots of a PERC battery, the PERC battery and application of the PERC battery.
Background
The PERC (Passivated Emitter and reader Cell) battery enhances the internal back reflection of light on a silicon substrate by performing a passivation technology on the back of the battery, reduces back recombination, has lower modification cost and also has the advantage of extremely high efficiency. In recent years, PERC cells have replaced conventional cells and become the prevalent solar cell in the industry.
At present, the PERC battery has EL (electroluminescence) defect, which is a physical phenomenon that an electric field is generated by voltages applied to two electrodes, electrons excited by the electric field collide with a luminescence center, and the jump, change and recombination of electronic energy levels cause luminescence. Therefore, the process of manufacturing the PERC cell is very strict, such as ultra-high cleanliness, strict transmission equipment and tool fixtures, which have strict requirements. The EL center exploded in the mass production of the PERC battery is dark and dark, and is more obvious in display under the back passivation process.
CN 109326684A discloses a method for solving the black spots of EL of PERC battery, wherein the aperture size of the water film spraying needle is 0.8mm, the water film device can slowly cover the silicon wafer, the water spraying pressure of the water film covering the silicon wafer is relieved, the pressure for covering the silicon wafer is reduced, the bad condition that the water film splashes around to pollute the surrounding silicon wafer is effectively reduced on the premise of ensuring the consistent water flow, the problem of the black spots of EL of PERC battery can be effectively solved, the pressure of the water film device can be relieved, the falling of the water film spraying needle can be effectively solved, the problem of pinhole blockage caused by long time and over-etching caused by insufficient water can be avoided, and equipment personnel need to replace and maintain irregularly.
CN 110277472A discloses a method for manufacturing a PERC battery, which comprises the steps of feeding a semi-finished product of a battery piece after oxidation treatment into a reaction cavity, and only enabling the back surface of the semi-finished product to be in contact with gas in the reaction cavity; vacuumizing the reaction cavity, introducing protective gas under a set pressure, heating the reaction cavity until the temperature and the vacuum degree in the reaction cavity reach set requirements, and introducing the reaction gas; and decomposing reaction gas molecules into plasma by using a radio frequency technology, wherein the plasma moves in the reaction cavity and impacts the back surface of the semi-finished product of the cell, so that the dirt on the back surface of the semi-finished product of the cell is separated from the semi-finished product of the cell.
CN 110931601A discloses a method for improving the PID resistance of a crystalline silicon solar cell, the method comprising the following steps: sending the PERC battery semi-finished silicon wafer plated with the aluminum oxide film layer into a coating machine, vacuumizing and heating to enable the cavity of the coating machine to reach a certain vacuum degree and temperature; introducing inert gas, simultaneously opening a vacuum pump valve to ensure that a certain pressure is maintained in the cavity, electrifying the radio frequency power supply to excite the inert gas into plasma, and pretreating the alumina film layer by using the plasma gas; exciting the pretreated silicon wafer into plasma by using mixed gas of silane and ammonia gas, and depositing a back silicon nitride film on the alumina film layer.
Based on the above research, how to provide a PERC cell with high cleanliness of the passivation film growth substrate and high compactness of the passivation film, and the passivation film is not easy to crack after high temperature sintering, has become a problem to be solved urgently.
Disclosure of Invention
The invention aims to provide a method for solving the central dark spot of a PERC battery EL, a PERC battery and application thereof, and aims to solve the defect of the central dark spot of the PERC battery by improving coating and sintering processes in the preparation process of the PERC battery, and avoid the problems that a dielectric layer is locally loose, and a passivation layer is cracked and damaged and locally fails after high-temperature sintering due to insufficient cleanliness of a growth substrate.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for solving the problem of dark spots in the center of an EL of a PERC cell, the method comprising coating and sintering in sequence;
the coating method comprises the following steps: introducing laughing gas under radio frequency power to pretreat the silicon wafer, keeping the pressure constant after the pretreatment of the silicon wafer, and then sequentially depositing aluminum oxide and silicon nitride;
the sintering comprises the following steps: the high-temperature main burning zone adopts a three-peak curve sintering mode, and the peak temperature is 775-785 ℃.
The peak temperature is 775 to 785 ℃, for example 775 ℃, 777 ℃, 779 ℃, 781 ℃, 783 ℃ or 785 ℃, but not limited to the values recited, other values not recited within the range of values are also applicable.
The preparation method of the PERC battery comprises the general process flows of texturing, diffusion, SE laser, oxidation, etching, annealing, back membrane, front membrane, back membrane laser grooving, screen printing, sintering, light injection or electric injection, test and sorting; the problem of dark spots in the center of the EL of the PERC battery is solved by improving a film coating method and a sintering process in the back film.
The invention adopts the laughing gas ionized into plasma to bombard the back surface of the silicon wafer under the acceleration of the electric field, thereby cleaning the ion and dust residue on the back surface and ensuring the high cleanliness of the growth substrate of the passive film; the invention improves the vacuum degree during film plating, reduces the power, prolongs the duty ratio, reduces the film plating rate and realizes the purpose of enhancing the compactness of the formed film of the aluminum oxide; by adjusting the sintering process, the back sintering mode is changed from a single peak value to a three-peak value mode, the temperature rising and falling slope of a sintering curve of the three-peak value mode becomes slow, the back membrane damage caused by temperature mutation is avoided, meanwhile, the temperature of a high-temperature main sintering area can be lowered to 775-785 ℃, and the problem of chapping caused by partial loosening of aluminum oxide after high-temperature sintering is solved.
The three-peak mode sintering refers to the fact that three peak temperatures exist in a sintering curve, and damage to a back membrane caused by single-peak mode sintering temperature mutation can be avoided.
Illustratively, the equipment used for coating the film comprises a PECVD alumina two-in-one furnace tube; the sintering furnace for sintering of the present invention comprises: the device comprises a drying zone, a pre-burning zone, a high-temperature main burning zone and a cooling zone.
Preferably, the pressure of the pretreated silicon wafer is 900-1100 mtorr, the flow rate of laughing gas is 5000-5500 sccm, the radio frequency power is 7500-8500W, and the pulse on-off ratio is (8-10): 190-210).
The pressure of the pretreated silicon wafer is 900-1100 mtorr, such as 900mtorr, 950mtorr, 1000mtorr, 1050mtorr or 1100mtorr, but is not limited to the values listed, and other values not listed in the range of values are equally applicable.
The flow rate of the laughing gas of the pretreated silicon wafer is 5000 to 5500sccm, for example, 5000sccm, 5100sccm, 5200sccm, 5300sccm, 5400sccm or 5500sccm, but is not limited to the values listed, and other values not listed within the range of values are also applicable.
The pulse switching ratio of the pretreated silicon wafer is (8-10) to (190-210), and can be, for example, 8.
Preferably, the constant pressure has a pressure of 750 to 850mtorr, a time of 15 to 25s, and a temperature of 330 to 350 ℃.
The pressure of the isopiestic pressure is 750 to 850mtorr, and may be, for example, 750mtorr, 770mtorr, 790mtorr, 810mtorr, 830mtorr or 850mtorr, but is not limited to the values recited, and other values not recited within the range of values are equally applicable.
The constant pressure is for a time of 15 to 25s, for example 15s, 17s, 19s, 21s, 23 or 25s, but is not limited to the values listed, and other values not listed in the numerical range are equally applicable.
The constant pressure temperature is 330 to 350 ℃, for example 330 ℃, 340 ℃ or 350 ℃, but is not limited to the values listed, and other values not listed in the numerical range are also applicable.
Preferably, TMA (trimethylaluminum) and laughing gas are pre-introduced at a constant pressure, and the flow rate of laughing gas is 5000 to 5500sccm, for example 5000sccm, 5100sccm, 5200sccm, 5300sccm, 5400sccm or 5500sccm, but the invention is not limited to the recited values, and other unrecited values within the range of values are equally applicable.
Preferably, in the mixed gas of the pre-introduced TMA and the laughing gas, TMA accounts for 50-60 vol%, for example, 50vol%, 55vol% or 60vol%, but the above-mentioned values are not limited thereto, and other values in the range of the values not listed are also applicable.
Preferably, the pressure at which the alumina is deposited is 700 to 900mtorr, such as 700mtorr, 750mtorr, 800mtorr, 850mtorr or 900mtorr, but is not limited to the values recited and other values not recited in the range of values are equally applicable.
Preferably, the temperature of the deposited alumina is 330-350 ℃, the radio frequency power is 6000-7000W, and the pulse on-off ratio is 1 (50-70).
The temperature at which the alumina is deposited is 330 to 350 c, which may be, for example, 330 c, 340 c or 350 c, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.
The RF power of the deposited alumina is 6000-7000W, such as 6000W, 6200W, 6400W, 6600W, 6800W or 7000W, but is not limited to the recited values, and other values not recited in the range of values are equally applicable.
The pulse on/off ratio of the deposited alumina is 1 (50-70), and can be, for example, 1.
Preferably, the atmosphere when the aluminum oxide is deposited is a mixed atmosphere of laughing gas and TMA, and the constant temperature and pressure time is 130-140 s.
The constant temperature and pressure of the deposited alumina is 130 to 140s, for example 130s, 132s, 134s, 136s, 138s or 140s, but not limited to the values recited, and other values not recited in the range of values are equally applicable.
According to the invention, when the alumina is deposited, the vacuum degree of the cavity is improved by reducing the flow of TMA and laughing gas, and meanwhile, the duty ratio is prolonged by reducing the radio frequency power, so that the density of the alumina is improved under the condition of realizing high-vacuum low-speed deposition.
Preferably, the flow rate of the mixed atmosphere is 5000 to 5500sccm, for example, 5000sccm, 5100sccm, 5200sccm, 5300sccm, 5400sccm or 5500sccm, but is not limited to the values listed, and other values not listed in the numerical range are also applicable.
Preferably, TMA is present in the mixed atmosphere in an amount of 50 to 60vol%, for example 50vol%, 55vol% or 60vol%, but not limited to the values recited, and other values not recited within the numerical range are also applicable.
Preferably, the coating method further comprises vacuumizing and ionizing between depositing aluminum oxide and depositing silicon nitride.
Preferably, the ionization temperature is 460-480 ℃, the time is 280-320 s, the pressure is 800-1000 mtorr, the radio frequency power is 6000-7000W, and the pulse on-off ratio is 5 (16-20).
Preferably, the ionized atmosphere is a mixed atmosphere of laughing gas and ammonia gas, wherein the flow rate of the laughing gas is 2400-2600 sccm, and the flow rate of the ammonia gas is 2400-2600 sccm.
The ionization temperature is 460 to 480 ℃, for example 460 ℃, 470 ℃ or 480 ℃, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.
The ionization time is 280 to 320s, for example 280s, 290s, 300s, 310s or 320s, but is not limited to the values listed, and other values not listed in the range of values are equally applicable.
The pressure of ionization is 800 to 1000mtorr, such as 800mtorr, 850mtorr, 900mtorr, 950mtorr or 1000mtorr, but is not limited to the values recited, and other values not recited in the range of values are equally applicable.
The ionizing rf power is 6000-7000W, such as 6000W, 6200W, 6400W, 6600W, 6800W or 7000W, but is not limited to the recited values, and other values not recited in the range of values are also applicable.
The ionization pulse on-off ratio is 5 (16 to 20), and can be, for example, 5.
The flow rate of laughing gas in the ionized atmosphere is 2400 to 2600sccm, which can be 2400sccm, 2500sccm, or 2600sccm, for example, but is not limited to the values listed, and other values not listed within the range of values are also applicable.
The flow rate of the ammonia gas in the ionized atmosphere is 2400 to 2600sccm, for example 2400sccm, 2500sccm or 2600sccm, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the vacuum is applied for 15 to 25 seconds, such as 15 seconds, 20 seconds, or 25 seconds, before the silicon nitride is deposited, but not limited to the recited values, and other values not recited in the range of values are equally applicable.
Preferably, the depositing of the silicon nitride includes sequentially depositing a first silicon nitride layer, a second silicon nitride layer and a third silicon nitride layer.
Preferably, the time for depositing the first silicon nitride layer is 280-320 s, the temperature is 460-480 ℃, the pressure is 1600-1800 mtorr, the flow rate of silane is 1000-1200 sccm, the flow rate of ammonia is 4800-4900 sccm, the radio frequency power is 13000-14000W, and the pulse switch ratio is 5 (65-75).
The time for depositing the first silicon nitride layer is 280s to 320s, for example, 280s, 290s, 300s, 310s or 320s, but is not limited to the values listed, and other values not listed in the range of values are also applicable.
The temperature at which the first silicon nitride layer is deposited is 460 to 480 c, and may be, for example, 460 c, 470 c or 480 c, but is not limited to the recited values, and other values within the range are equally applicable.
The pressure at which the first silicon nitride layer is deposited is 1600 to 1800mtorr, which may be, for example, 1600mtorr, 1700mtorr or 1800mtorr, but is not limited to the values recited, and other values within the range that are not recited are equally applicable.
The silane flow rate for depositing the first silicon nitride layer is 1000sccm to 1200sccm, such as 1000sccm, 1100sccm, or 1200sccm, but is not limited to the values recited, and other values not recited within the range of values are equally applicable.
The flow rate of the ammonia gas to deposit the first silicon nitride layer can be 4800sccm to 4900sccm, such as 4800sccm, 4850sccm, or 4900sccm, but is not limited to the values recited, and other values not recited within the range of values are equally suitable.
The rf power for depositing the first silicon nitride layer is 13000-14000W, and can be, for example, 13000W, 13500W, or 14000W, but is not limited to the values recited, and other values not recited in the range of values are equally applicable.
The pulse on/off ratio for depositing the first silicon nitride layer is 5 (65-75), and may be, for example, 5.
Preferably, the second silicon nitride layer is deposited for 30-50 s at 460-480 deg.C under 1600-1800 mtorr, with silane flow of 1000-1200 sccm, ammonia flow of 6300-6700 sccm, RF power of 14000-15000W, and pulse on/off ratio of 5 (55-65).
The time for depositing the second silicon nitride layer is 30 to 50s, and may be, for example, 30s, 40s, or 50s, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.
The temperature at which the second silicon nitride layer is deposited is 460 to 480 c, and may be, for example, 460 c, 470 c or 480 c, and is not limited to the values recited, and other values not recited within the range of values are equally applicable.
The pressure at which the second silicon nitride layer is deposited is 1600 to 1800mtorr, which may be, for example, 1600mtorr, 1700mtorr or 1800mtorr, but is not limited to the values recited and other values not recited within the range of values are equally suitable.
The flow rate of silane for depositing the second silicon nitride layer is 1000 to 1200sccm, such as 1000sccm, 1100sccm, or 1200sccm, but is not limited to the values recited, and other values not recited within the range of values are equally applicable.
The flow rate of the ammonia gas for depositing the second silicon nitride layer is 6300 to 6700sccm, and may be, for example, 6300sccm, 6500sccm or 6700sccm, but is not limited to the values recited, and other values not recited within the range of values are also applicable.
The rf power for depositing the second silicon nitride layer is 14000W to 15000W, and may be, for example, 14000W, 14500W or 15000W, but is not limited to the values recited, and other values not recited within the range of values are equally applicable.
The pulse on/off ratio for depositing the second silicon nitride layer is 5 (65-75), and may be, for example, 5.
Preferably, the third silicon nitride layer is deposited for 230-270 s at 460-480 deg.c and 1600-1800 mtorr at 790-800 sccm silane flow rate, 6300-6700 sccm ammonia gas flow rate, 14000-15000W radio frequency power and 5 (55-65) pulse on-off ratio.
The deposition time of the third silicon nitride layer is 230 to 270s, and may be, for example, 230s, 240s, 250s, 260s, or 270s, but is not limited to the values recited, and other values not recited in the range of values are also applicable.
The temperature at which the third silicon nitride layer is deposited is 460 to 480 c, and may be, for example, 460 c, 470 c or 480 c, but is not limited to the recited values, and other values within the range are equally applicable.
The pressure at which the third silicon nitride layer is deposited is 1600 to 1800mtorr, which may be 1600mtorr, 1700mtorr or 1800mtorr, for example, but is not limited to the values recited, and other values not recited in the range of values are equally applicable.
The flow rate of silane for depositing the third silicon nitride layer is 790 to 800sccm, such as 790sccm, 795sccm, or 800sccm, but is not limited to the values recited, and other values not recited within the range of values are equally applicable.
The flow rate of the ammonia gas for depositing the third silicon nitride layer is 6300sccm to 6700sccm, such as 6300sccm, 6500sccm, or 6700sccm, but is not limited to the values recited, and other values not recited within the range of values are equally applicable.
The rf power for depositing the third silicon nitride layer is 14000W to 15000W, which can be, for example, 14000W, 14500W or 15000W, but is not limited to the values recited and other values not recited within the range of values are equally applicable.
The pulse on/off ratio for depositing the third silicon nitride layer is 5 (65-75), and may be, for example, 5.
Preferably, the method comprises the steps of heating, vacuumizing and detecting leakage before pretreating the silicon wafer.
Preferably, the temperature rise is 340-360 ℃, the time is 250-300 s, and the pressure is 900-1100 mtorr.
The temperature of the elevated temperature is 340 to 360 ℃, for example 340 ℃, 350 ℃ or 360 ℃, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.
The temperature rise time is 250 to 300s, and may be, for example, 250s, 260s, 270s, 280s, 290s or 300s, but is not limited to the values listed, and other values not listed in the numerical range are also applicable.
The elevated temperature pressure is 900 to 1100mtorr, and may be, for example, 900mtorr, 1000mtorr or 1100mtorr, but is not limited to the values recited, and other values not recited within the range of values are also applicable.
Preferably, the time for raising the temperature and then evacuating is 280 to 300s, for example, 280s, 290s or 300s, but is not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, after the silicon nitride is deposited, vacuumizing is carried out, and the pressure returns to normal pressure, so that the film coating is completed.
Preferably, the time for vacuumizing after the silicon nitride is deposited is 20-30 s, and the temperature is 420-440 ℃.
The time for vacuuming after depositing the silicon nitride is 20 to 30s, for example, 20s, 25s or 30s, but is not limited to the recited values, and other values in the range of the recited values are also applicable.
The temperature of the vacuum after deposition of the silicon nitride is 420 to 440 ℃, for example, 420 ℃, 430 ℃ or 440 ℃, but not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the time for returning to the normal pressure is 80-100 s, the pressure is 900-1100 mtorr, and the flow of ammonia gas is 4800-5200 sccm.
The time to return to atmospheric pressure is 80 to 100s, and may be, for example, 80s, 90s or 100s, but is not limited to the values recited, and other values not recited in the numerical range are also applicable.
The return pressure to atmospheric pressure is from 900 to 1100mtorr, and may be, for example, 900mtorr, 1000mtorr or 1100mtorr, but is not limited to the values recited, and other values not recited within the range of values are equally applicable.
The flow rate of the ammonia gas under the atmospheric pressure is 4800 to 5200sccm, for example 4800sccm, 5000sccm or 5200sccm, but the present invention is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.
As a preferable technical scheme of the invention, the method comprises the steps of sequentially coating and sintering;
the coating method comprises the following steps:
(1) Sequentially heating, vacuumizing and detecting leakage;
(2) Pretreating a silicon wafer by using laughing gas, wherein the pressure of the pretreated silicon wafer is 900-1100 mtorr, the flow rate of the laughing gas is 5000-5500 sccm, the radio frequency power is 7500-8500W, and the pulse on-off ratio is (8-10) to (190-210);
(3) After the silicon chip is pretreated, the pressure is constant, the pressure of the constant pressure is 750-850 mtorr, the time is 15-25 s, and the temperature is 330-350 ℃;
TMA and laughing gas are introduced in advance at constant pressure, and the flow rate of the laughing gas is 5000-5500 sccm.
(4) Depositing aluminum oxide, wherein the pressure of the deposited aluminum oxide is 700-900 mtorr, the temperature is 330-350 ℃, the radio frequency power is 6000-7000W, the pulse switching ratio is 1 (50-70), the atmosphere is the mixed atmosphere of laughing gas and TMA, and the constant temperature and pressure time is 130-140 s;
(5) Carrying out ionization after vacuum pumping, wherein the ionization temperature is 460-480 ℃, the time is 280-320 s, the pressure is 800-1000 mtorr, the radio frequency power is 6000-7000W, the pulse switching ratio is 5 (16-20), the atmosphere is laughing gas and ammonia gas, the flow rate of the laughing gas is 2400-2600 sccm, and the flow rate of the ammonia gas is 2400-2600 sccm;
(6) Vacuumizing for 15-25 s after ionization, and then sequentially depositing a first silicon nitride layer, a second silicon nitride layer and a third silicon nitride layer;
(7) After three layers of silicon nitride are deposited, vacuumizing is carried out, and the pressure returns to normal pressure, so that film coating is completed;
the sintering comprises the following steps: the high-temperature main burning zone adopts a three-peak curve sintering mode, and the peak temperature is 775-785 ℃.
In a second aspect, the present invention provides a PERC cell obtained by the method of the first aspect.
In a third aspect, the invention provides a use of the PERC cell according to the second aspect, including a use in the field of photovoltaic modules.
Compared with the prior art, the invention has the following beneficial effects:
the invention solves the problem of the EL center dark spot of the PERC battery by improving the coating and sintering process in the preparation process of the PERC battery; the invention adopts laughing gas ionized into plasma to bombard the back surface of the silicon wafer under the acceleration of the electric field, thereby cleaning the residual ions and dust on the back surface and ensuring the high cleanliness of the growth substrate of the passive film; according to the invention, by improving the method for coating on the silicon wafer, the vacuum degree during coating is improved, the power is reduced, the duty ratio is prolonged, the coating speed is reduced, and the compactness of the alumina film is enhanced; by adjusting the sintering process, the back sintering mode is changed from a single peak value to a three-peak value mode, the temperature rising and falling slope of a sintering curve of the three-peak value mode becomes slow, the back membrane damage caused by temperature mutation is avoided, meanwhile, the temperature of a high-temperature main sintering area can be lowered to 775-785 ℃, and the problem of chapping caused by partial loosening of aluminum oxide after high-temperature sintering is solved.
Drawings
FIG. 1 is a graph of the sintering curves provided in example 1 and comparative example 1.
Fig. 2 is a partial enlarged view of the sintering profile provided in example 1 and comparative example 1.
Fig. 3 is an EL diagram of the PERC cell provided in example 1.
Fig. 4 is an EL diagram of the PERC cell provided in comparative example 1.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitation of the present invention.
The general process for the preparation of the PERC cell in the embodiment of the invention comprises texturing-diffusion-SE laser-oxidation-etching-annealing-back film-front film-back film laser grooving-screen printing-sintering-light injection-test sorting, with the exception of the specially emphasized coating and sintering process steps, the other operating parameters being the same for each example as for the comparative example.
Example 1
The preparation method of the PERC battery comprises the following general process flows of texturing, diffusion, SE laser, oxidation, etching, annealing, back film, front film, back film laser grooving, screen printing, sintering, light injection or electric injection, test sorting and the like, so that the PERC battery is obtained;
the coating comprises the following steps:
(1) Entering a boat: placing a silicon wafer on a graphite bearing clamp, and sending the silicon wafer into tubular PECVD coating equipment by a mechanical arm for 110s at the temperature of 350 ℃ and the pressure of 1000mtorr;
and (3) heating: the mechanical arm is drawn out of the furnace tube, the furnace is closed, and the temperature is raised for 280s at 350 ℃ and 1000mtorr;
vacuumizing: vacuumizing the furnace tube after heating for 290s at 350 ℃;
and (3) leak detection: testing whether vacuum leaks or not so as to ensure the process effect before process gas is introduced, wherein the leak detection time is 20s, the temperature is 350 ℃, and the pressure is 1000mtorr;
(2) Pretreating a silicon wafer by adopting laughing gas, wherein the pressure of the pretreated silicon wafer is 1000mtorr, the flow of the laughing gas is 5200sccm, the radio-frequency power is 8000W, and the pulse on-off ratio is 9;
(3) After the silicon wafer is pretreated, keeping the pressure at constant pressure, wherein the pressure at constant pressure is 800mtorr, the time is 20s, and the temperature is 340 ℃;
TMA and laughing gas are introduced in advance at constant pressure, and the flow rate of the laughing gas is 5200sccm;
(4) Depositing aluminum oxide, wherein the pressure of the deposited aluminum oxide is 800mtorr, the temperature is 340 ℃, the radio frequency power is 6500W, the pulse switching ratio is 1;
the flow rate of the mixed atmosphere is 5200sccm, wherein TMA accounts for 55vol%;
(5) Vacuumizing for 20s at 350 ℃, and pumping away redundant reaction gas;
performing ionization after vacuumizing, wherein the ionization temperature is 470 ℃, the time is 300s, the pressure is 900mtorr, the radio frequency power is 6500W, the pulse switching ratio is 5/18, the atmosphere is laughing gas and ammonia gas, the flow of the laughing gas is 2500sccm, and the flow of the ammonia gas is 2500sccm;
(6) Vacuumizing for 20s at 450 ℃ after ionization, and then sequentially depositing a first silicon nitride layer, a second silicon nitride layer and a third silicon nitride layer;
the time for depositing the first silicon nitride layer is 300s, the temperature is 470 ℃, the pressure is 1700mtorr, the silane flow is 1100sccm, the ammonia gas flow is 4880sccm, the radio frequency power is 13500W, and the pulse on-off ratio is 5;
the time for depositing the second silicon nitride layer is 40s, the temperature is 470 ℃, the pressure is 1700mtorr, the silane flow is 1066sccm, the ammonia gas flow is 6500sccm, the radio frequency power is 14500W, and the pulse on-off ratio is 5;
the time for depositing the third silicon nitride layer is 250s, the temperature is 470 ℃, the pressure is 1700mtorr, the silane flow is 793sccm, the ammonia gas flow is 6500sccm, the radio frequency power is 14500W, and the pulse on-off ratio is 5;
(7) After depositing silicon nitride, vacuumizing for 25s at 430 ℃, returning to normal pressure, opening a furnace door, taking a graphite boat, and finishing film coating;
the time for returning to the normal pressure is 90s, the temperature is 430 ℃, the pressure is 1000mtorr, and the flow of ammonia gas is 5000sccm.
The sintering comprises the following steps: the high-temperature main burning zone adopts a three-peak curve sintering mode, and the peak temperature is 780 ℃.
The sintering curve of this example is shown in fig. 1, a partial enlarged view of the sintering curve is shown in fig. 2, and the EL map of the PERC cell is shown in fig. 3.
Example 2
The preparation method of the PERC battery comprises the following general process flows of texturing, diffusion, SE laser, oxidation, etching, annealing, back film, front film, back film laser grooving, screen printing, sintering, light injection or electric injection, testing and sorting, and the PERC battery is obtained;
the coating comprises the following steps:
(1) Entering a boat: placing a silicon wafer on a graphite bearing clamp, and sending the silicon wafer into tubular PECVD coating equipment by a mechanical arm for 110s at the temperature of 350 ℃ and the pressure of 1000mtorr;
and (3) heating: the mechanical arm is drawn out of the furnace tube, the furnace is closed, and the temperature is raised for 280s at 350 ℃ and 1000mtorr;
vacuumizing: vacuumizing the furnace tube after heating for 290s at 350 ℃;
and (3) leak detection: testing whether vacuum leaks or not so as to ensure the process effect before process gas is introduced, wherein the leak detection time is 20s, the temperature is 350 ℃, and the pressure is 1000mtorr;
(2) Pretreating a silicon wafer by adopting laughing gas, wherein the pressure of the pretreated silicon wafer is 900mtorr, the flow rate of the laughing gas is 5000sccm, the radio frequency power is 7500W, and the pulse on-off ratio is 8;
(3) After the silicon wafer is pretreated, carrying out constant pressure, wherein the pressure of the constant pressure is 850mtorr, the time is 25s, and the temperature is 350 ℃;
TMA and laughing gas are introduced in advance at constant pressure, and the flow rate of the laughing gas is 5500sccm;
(4) Depositing alumina, wherein the pressure of the deposited alumina is 700mtorr, the temperature is 330 ℃, the radio frequency power is 6000W, the pulse switching ratio is 1;
(5) Vacuumizing for 20s at 350 ℃, and pumping away redundant reaction gas;
carrying out ionization after vacuumizing, wherein the ionization temperature is 460 ℃, the time is 280s, the pressure is 800mtorr, the radio-frequency power is 6000W, the pulse switching ratio is 5;
(6) Vacuumizing at 450 ℃ for 25s after ionization, and then sequentially depositing a first silicon nitride layer, a second silicon nitride layer and a third silicon nitride layer;
the time for depositing the first silicon nitride layer is 320s, the temperature is 480 ℃, the pressure is 1800mtorr, the silane flow is 1200sccm, the ammonia gas flow is 4900sccm, the radio frequency power is 14000W, and the pulse on-off ratio is 5;
the time for depositing the second silicon nitride layer is 30s, the temperature is 460 ℃, the pressure is 1600mtorr, the silane flow rate is 1000sccm, the ammonia gas flow rate is 6300sccm, the radio frequency power is 14000W, and the pulse on-off ratio is 5;
the third silicon nitride layer is deposited for 270s at 480 ℃ and under 1800mtorr, the silane flow rate is 800sccm, the ammonia gas flow rate is 6700sccm, the radio frequency power is 15000W, and the pulse on-off ratio is 5;
(7) After depositing silicon nitride, vacuumizing for 25s at 430 ℃, returning to normal pressure, opening a furnace door, taking a graphite boat, and finishing film coating;
the time for returning to the normal pressure is 80s, the pressure is 900mtorr, and the flow of the ammonia gas is 4800sccm.
The sintering comprises the following steps: the high-temperature main burning zone adopts a three-peak curve sintering mode, and the peak temperature is 785 ℃.
Example 3
The preparation method of the PERC battery comprises the following general process flows of texturing, diffusion, SE laser, oxidation, etching, annealing, back film, front film, back film laser grooving, screen printing, sintering, light injection or electric injection, test sorting and the like, so that the PERC battery is obtained;
the coating comprises the following steps:
(1) Entering a boat: placing a silicon wafer on a graphite bearing clamp, and sending the silicon wafer into tubular PECVD coating equipment by a mechanical arm for 110s at the temperature of 350 ℃ and the pressure of 1000mtorr;
and (3) heating: the mechanical arm is drawn out of the furnace tube, the furnace is closed, and the temperature is raised for 280s at 350 ℃ and 1000mtorr;
vacuumizing: vacuumizing the furnace tube after heating, wherein the time is 290s, and the temperature is 350 ℃;
and (3) leak detection: testing whether vacuum leaks or not so as to ensure the process effect before process gas is introduced, wherein the leak detection time is 20s, the temperature is 350 ℃, and the pressure is 1000mtorr;
(2) Pretreating a silicon wafer by adopting laughing gas, wherein the pressure of the pretreated silicon wafer is 1100mtorr, the flow of the laughing gas is 5500sccm, the radio frequency power is 8500W, and the pulse on-off ratio is 10;
(3) After the silicon wafer is pretreated, keeping the pressure at 750mtorr, the time at 15s and the temperature at 330 ℃;
TMA and laughing gas are introduced in advance during constant pressure, and the flow rate of the laughing gas is 5000sccm;
(4) Depositing aluminum oxide, wherein the pressure of the deposited aluminum oxide is 900mtorr, the temperature is 350 ℃, the radio frequency power is 7000W, the pulse on-off ratio is 1 to 70, the atmosphere is a mixed atmosphere of laughing gas and TMA, and the time of constant temperature and constant pressure is 140s;
(5) Vacuumizing for 20s at 350 ℃, and pumping away redundant reaction gas;
performing ionization after vacuumizing, wherein the ionization temperature is 480 ℃, the time is 320s, the pressure is 1000mtorr, the radio frequency power is 7000W, the pulse on-off ratio is 5;
(6) Vacuumizing for 15s at 450 ℃ after ionization, and then sequentially depositing a first silicon nitride layer, a second silicon nitride layer and a third silicon nitride layer;
the time for depositing the first silicon nitride layer is 280s, the temperature is 460 ℃, the pressure is 1600mtorr, the silane flow is 1000sccm, the ammonia gas flow is 4800sccm, the radio frequency power is 13000W, and the pulse on-off ratio is 5;
the time for depositing the second silicon nitride layer is 50s, the temperature is 480 ℃, the pressure is 1800mtorr, the silane flow is 1200sccm, the ammonia gas flow is 6700sccm, the radio frequency power is 15000W, and the pulse on-off ratio is 5;
the time for depositing the third silicon nitride layer is 230s, the temperature is 460 ℃, the pressure is 1600mtorr, the silane flow is 700sccm, the ammonia gas flow is 6300sccm, the radio frequency power is 14000W, and the pulse on-off ratio is 5;
(7) After depositing silicon nitride, vacuumizing for 25s at 430 ℃, returning to normal pressure, opening a furnace door, taking a graphite boat, and finishing film coating;
the time for returning to the normal pressure is 100s, the pressure is 1100mtorr, and the flow of the ammonia gas is 5200sccm.
The sintering comprises the following steps: the high-temperature main burning zone adopts a three-peak curve sintering mode, and the peak temperature is 775 ℃.
Example 4
The preparation method of the PERC battery comprises the following general process flows of texturing, diffusion, SE laser, oxidation, etching, annealing, back film, front film, back film laser grooving, screen printing, sintering, light injection or electric injection, testing and sorting, and the PERC battery is obtained;
the coating is the same as that of example 1 except that the pressure for depositing the alumina in the step (4) is 1000mtorr;
the sintering method was the same as in example 1.
Example 5
The preparation method of the PERC battery comprises the following general process flows of texturing, diffusion, SE laser, oxidation, etching, annealing, back film, front film, back film laser grooving, screen printing, sintering, light injection or electric injection, testing and sorting, and the PERC battery is obtained;
the coating is the same as that of the embodiment 1 except that the radio frequency power of the deposited alumina in the step (4) is 7500W;
the sintering method was the same as in example 1.
Example 6
The preparation method of the PERC battery comprises the following general process flows of texturing, diffusion, SE laser, oxidation, etching, annealing, back film, front film, back film laser grooving, screen printing, sintering, light injection or electric injection, test sorting and the like, so that the PERC battery is obtained;
the coating is the same as that of the embodiment 1 except that the pressure of the deposited alumina in the step (4) is 1000mtorr and the radio frequency power is 7500W;
the sintering method was the same as in example 1.
Comparative example 1
The present comparative example provides a PERC cell (M6-9 BB PERC cell) prepared by a method comprising the general process flow of texturing-diffusion-SE laser-oxidation-etching-annealing-back film-front film-back film laser grooving-screen printing-sintering-photo-injection or electro-injection-test sorting;
the sintering curve provided by this comparative example is shown in fig. 1, a partial enlarged view of the sintering curve is shown in fig. 2, and the EL map of the PERC cell is shown in fig. 4.
Comparative example 2
The present comparative example provides a PERC cell, the method of making the PERC cell comprising the general process flow of texturing-diffusion-SE laser-oxidation-etching-annealing-back film-front film-back film laser grooving-screen printing-sintering-light injection or electrical injection-test sorting;
the preparation method of the PERC battery is the same as that of the embodiment 1 except that the film plating does not comprise the laughing gas pretreatment in the step (2).
The sintering method was the same as in example 1.
Comparative example 3
The preparation method of the PERC battery comprises the following general process flows of texturing, diffusion, SE laser-oxidation, etching, annealing, back film, positive film, back film laser grooving, screen printing, sintering, light injection or electric injection, test and sorting to obtain the PERC battery;
the coating method in the back film is the same as that of the embodiment 1.
The sintering comprises the following steps: the high-temperature main burning zone adopts a unimodal value sintering mode, and the peak temperature is 800 ℃.
The electrical performance test methods (using the hall test standard) and results for the PERC cells obtained in the above examples and comparative examples are as follows:
the test results are shown in table 1:
TABLE 1
| Uoc/V | Isc/A | Rser/mΩ | Rshunt/Ω | FF/％ | Eta/％ | IRev2/A | |
| Example 1 | 0.6919 | 11.218 | 0.00021 | 1177 | 80.70 | 22.85 | 0.057 |
| Example 2 | 0.6915 | 11.210 | 0.00021 | 1100 | 80.65 | 22.80 | 0.077 |
| Example 3 | 0.6910 | 11.205 | 0.00020 | 1099 | 80.60 | 22.76 | 0.096 |
| Example 4 | 0.6908 | 11.208 | 0.00022 | 1188 | 80.63 | 22.77 | 0.085 |
| Example 5 | 0.6912 | 11.200 | 0.00022 | 1143 | 80.63 | 22.77 | 0.085 |
| Example 6 | 0.6909 | 11.205 | 0.00022 | 1377 | 80.63 | 22.77 | 0.085 |
| Comparative example 1 | 0.6883 | 11.185 | 0.00227 | 1553 | 80.00 | 22.47 | 0.052 |
| Comparative example 2 | 0.6873 | 11.170 | 0.00225 | 1653 | 79.91 | 22.38 | 0.042 |
| Comparative example 3 | 0.6865 | 11.155 | 0.00220 | 1233 | 79.80 | 22.29 | 0.062 |
Uoc is open-circuit voltage, isc is short-circuit current, rser is series resistance, rshunt is parallel resistance, FF is fill factor, eta is battery conversion efficiency, and IRev2 is reverse current 2 (-12V).
From table 1, the following points can be seen:
(1) As can be seen from the embodiments 1 and 4 to 6, the pressure for depositing alumina in the film plating process in the embodiment 1 is lower, and the radio frequency power is lower, that is, the vacuum degree is improved, the duty ratio is prolonged, and the alumina is deposited at a high vacuum and a low speed, so that compared with the embodiment 1, the density of the alumina film of the PERC battery provided in the embodiments 4 to 6 is reduced to some extent, and the electrochemical performance is reduced; therefore, the vacuum degree during the film coating is improved, the power is reduced, the duty ratio is prolonged, the film coating speed is reduced, the compactness of the formed aluminum oxide film is enhanced, and the performance of the PERC battery is improved.
(2) As can be seen from the example 1 and the comparative example 1, after the PERC cell provided in the example 1 is subjected to the optimization process, the problem of dark spots is eliminated, the open-circuit voltage is increased, the current gain is obvious, and the cell conversion efficiency is increased by 0.47%.
(3) As can be seen from example 1 and comparative example 2, comparative example 2 did not use laughing gas for pretreatment of the silicon wafer, resulting in low cleanliness of the silicon wafer, and thus the performance of the PERC cell provided in comparative example 2 was degraded; as can be seen from example 1 and comparative example 3, in comparative example 3, a unimodal sintering mode is adopted, the temperature jump may damage the back film, and the deposited aluminum oxide layer may have a local loose and cracked problem, resulting in a decrease in performance of the PERC cell provided in comparative example 3.
In summary, the invention provides a method for solving the problem of the EL center dark spot of the PERC battery, the PERC battery and the application thereof, wherein the method comprises the steps of sequentially coating and sintering; the coating method comprises the following steps: introducing laughing gas under radio frequency power to pretreat the silicon wafer, keeping the pressure constant after the pretreatment of the silicon wafer, and then sequentially depositing aluminum oxide and silicon nitride; the sintering comprises the following steps: the high-temperature main burning zone adopts a three-peak curve sintering mode, and the peak temperature is 775-785 ℃. The invention solves the problem of the EL center dark spot of the PERC battery by improving the coating and sintering process in the preparation process of the PERC battery. Cleaning the back surface by adopting laughing gas ionized into plasma, and ensuring the high cleanliness of the growth substrate of the passive film; the method for coating the film on the silicon wafer is improved, so that the high-vacuum low-speed deposition of the alumina is realized, and the density of the alumina is improved; by adjusting the sintering process, the damage of the back membrane caused by temperature mutation is avoided, and the problem of chapping of local loose alumina after high-temperature sintering is solved.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (22)
1. A method for solving the problem of EL central dark spots of a PERC battery is characterized by comprising the steps of sequentially coating and sintering;
the coating method comprises the following steps: introducing laughing gas under radio frequency power to pretreat the silicon wafer, keeping the pressure constant after the silicon wafer is pretreated, and then sequentially depositing aluminum oxide and silicon nitride;
the pressure of the constant pressure is less than that of the pretreated silicon wafer;
the pressure of the deposited alumina is 700-900 mtorr, and the radio frequency power is 6200-7000W;
the sintering comprises the following steps: the high-temperature main burning zone adopts a three-peak curve sintering mode, and the peak temperature is 775-785 ℃.
2. The method of claim 1, wherein the pressure of the pretreated silicon wafer is 900-1100 mtorr, the flow rate of laughing gas is 5000-5500 sccm, the radio frequency power is 7500-8500W, and the pulse on/off ratio is (8-10): 190-210.
3. The method according to claim 1 or 2, wherein the constant pressure is at a pressure of 750 to 850mtorr, for a time of 15 to 25s and at a temperature of 330 to 350 ℃.
4. The method as claimed in claim 1 or 2, wherein a mixed gas of TMA and laughing gas is pre-introduced at a constant pressure, and a flow rate of laughing gas is 5000 to 5500sccm.
5. The method of claim 4, wherein TMA is 50-60 vol% of the pre-mixed gas of TMA and laughing gas.
6. The method of claim 1 or 2, wherein the temperature of the deposited alumina is 330-350 ℃ and the pulse on-off ratio is 1 (50-70).
7. The method according to claim 1 or 2, wherein the atmosphere for depositing the alumina is a mixed atmosphere of laughing gas and TMA, and the constant temperature and pressure time is 130 to 140 seconds.
8. The method of claim 7, wherein the flow rate of the mixed atmosphere is 5000 to 5500sccm.
9. The method of claim 8, wherein TMA is present in the mixed atmosphere in an amount of 50 to 60vol%.
10. The method of claim 1, wherein the coating method further comprises vacuum and ionization between depositing aluminum oxide and depositing silicon nitride.
11. The method of claim 10, wherein the ionization temperature is 460-480 ℃, the time is 280-320 s, the pressure is 800-1000 mtorr, the radio frequency power is 6000-7000W, and the pulse on/off ratio is 5 (16-20).
12. The method of claim 10, wherein the ionized atmosphere is a mixed atmosphere of laughing gas and ammonia gas, wherein the flow rate of laughing gas is 2400-2600 sccm and the flow rate of ammonia gas is 2400-2600 sccm.
13. The method of claim 1, wherein the vacuum is applied for 15 to 25 seconds before the silicon nitride is deposited.
14. The method of claim 1, wherein depositing silicon nitride comprises sequentially depositing a first silicon nitride layer, a second silicon nitride layer, and a third silicon nitride layer.
15. The method of claim 14, wherein the first silicon nitride layer is deposited for a time of 280-320 s, at a temperature of 460-480 ℃, at a pressure of 1600-1800 mtorr, at a silane flow of 1000-1200 sccm, at an ammonia flow of 4800-4900 sccm, at a radio frequency power of 13000-14000W, and at a pulse switching ratio of 5 (65-75).
16. The method of claim 14, wherein the second silicon nitride layer is deposited for a time of 30 to 50s, at a temperature of 460 to 480 ℃, at a pressure of 1600 to 1800mtorr, at a silane flow rate of 1000 to 1200sccm, at an ammonia gas flow rate of 6300 to 6700sccm, at a radio frequency power of 14000 to 15000W, and at a pulse on/off ratio of 5 (55 to 65).
17. The method of claim 14, wherein the third silicon nitride layer is deposited for a period of 230 to 270 seconds, at a temperature of 460 to 480 ℃, at a pressure of 1600 to 1800mtorr, at a silane flow rate of 790 to 800sccm, at an ammonia gas flow rate of 6300 to 6700sccm, at a radio frequency power of 14000 to 15000W, and at a pulse on/off ratio of 5 (55 to 65).
18. The method of claim 1, wherein the method comprises evacuating and detecting leaks after the temperature is raised prior to pretreating the wafer.
19. The method of claim 1, wherein the silicon nitride is deposited, then the vacuum is applied, and the pressure is returned to normal pressure to complete the coating.
20. The method according to claim 1, comprising coating and sintering in sequence;
the coating method comprises the following steps:
(1) Sequentially heating, vacuumizing and detecting leakage;
(2) Pretreating a silicon wafer by using laughing gas, wherein the pressure of the pretreated silicon wafer is 900-1100 mtorr, the flow rate of the laughing gas is 5000-5500 sccm, the radio frequency power is 7500-8500W, and the pulse on-off ratio is (8-10) to (190-210);
(3) After the silicon chip is pretreated, the pressure is constant, the pressure of the constant pressure is 750-850 mtorr, the time is 15-25 s, and the temperature is 330-350 ℃;
TMA and laughing gas are introduced in advance at constant pressure, and the flow rate of the laughing gas is 5000-5500 sccm;
(4) Depositing aluminum oxide, wherein the pressure of the deposited aluminum oxide is 700-900 mtorr, the temperature is 330-350 ℃, the radio frequency power is 6200-7000W, the pulse switching ratio is 1 (50-70), the atmosphere is a mixed atmosphere of laughing gas and TMA, the TMA accounts for 50-60 vol% in the mixed atmosphere, and the time of constant temperature and constant pressure is 130-140 s;
(5) Carrying out ionization after vacuum pumping, wherein the ionization temperature is 460-480 ℃, the time is 280-320 s, the pressure is 800-1000 mtorr, the radio frequency power is 6000-7000W, the pulse switching ratio is 5 (16-20), the atmosphere is a mixed atmosphere of laughing gas and ammonia gas, the flow of the laughing gas is 2400-2600 sccm, and the flow of the ammonia gas is 2400-2600 sccm;
(6) Vacuumizing for 15-25 s after ionization, and then sequentially depositing a first silicon nitride layer, a second silicon nitride layer and a third silicon nitride layer;
(7) After three layers of silicon nitride are deposited, vacuumizing is carried out, and the pressure returns to normal pressure, so that the film coating is finished;
the sintering comprises the following steps: the high-temperature main burning zone adopts a three-peak curve sintering mode, and the peak temperature is 775-785 ℃.
21. A PERC cell, wherein said PERC cell is obtained by the method of any one of claims 1 to 20.
22. Use of the PERC cell of claim 21, comprising use in the field of photovoltaic modules.
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Denomination of invention: A Method for Solving the Dark Spot in the EL Center of PERC Batteries, PERC Batteries and Their Applications Effective date of registration: 20230913 Granted publication date: 20221125 Pledgee: Dongyang Branch of China Construction Bank Co.,Ltd. Pledgor: HENGDIAN GROUP DMEGC MAGNETICS Co.,Ltd. Registration number: Y2023330002029 |