Detailed explanation of the process mechanism of each process of TOPCON
Texturing
The texturing section (a total of 6 lines) includes pre-cleaning - pure water washing before texturing - texturing *3 - pure water washing after texturing - post-cleaning pure water washing - pickling - pure water washing after pickling - slow lifting pre-dehydration - drying *5 and other modules. The texturing method of this project all adopts automatic texturing, the whole operation process is carried out automatically, the conveyor arm will be sent to the feeding place of the texturing machine after pre-cleaning, the silicon wafer in the automatic closed texturing machine through the roller through each corrosion, cleaning tank, equipment automatic control to supplement the acid, lye and pure water in each module, the acid and lye in the tank are pumped in through the pipeline, and regularly (a single tank volume of 720L, 48h to replace once) discharge the wastewater in the tank.
1) Pre-cleaning
Pre-cleaning purpose: Remove impurities (organic matter, metal impurities, etc.) adhered to the surface of the silicon wafer, using NaOH solution and H2O2 solution.
The loaded silicon wafers are immersed in the pre-cleaning tank in turn, pure water is added to the tank, and an appropriate amount of NaOH solution or cleaning solution is added according to the ratio (NaOH concentration is expected to be 0.6% after mixing, H2O2 concentration is expected to be 1.5%, automatic addition) for high-temperature cleaning (60 °C). Pre-cleaning uses ultrasonic cleaning. Pure water cleaning after pre-cleaning. Pure water cleaning is all overflow immersion cleaning, all carried out at room temperature.
The chemical reactions that occur during the pre-cleaning process are as follows:
Si+2NaOH+H2O=Na2SiO3+2H2↑
2) Alkali texturing
Objective: To carry out anisotropic corrosion of crystal on the silicon surface by lye to form a pyramid with a surface size of 5um, and the pyramid suede surface has excellent light trapping and anti-reflection effect (10%). Alkali texturing uses NaOH solution and texturing additives.
Add an appropriate amount of NaOH solution and texturing additives (NaOH solution concentration of about 0.6%, texturing additive concentration of about 0.4%) to the alkali pile tank, which can reduce the surface tension of silicon wafers, improve the wetting effect of silicon wafers and NaOH liquid, and promote the release of hydrogen bubbles, enhance the anisotropy of corrosion, make the pyramid more uniform and consistent, and improve the production effect of suede surface. The chemical reaction process of the formation of suede is as follows:
Si+2NaOH+H2O=Na2SiO3+2H2↑
The working temperature of the alkali texturing tank is 82 °C, and the control time of alkali texturing is 420s.
3) Wash afterward
The silicon wafer after alkali texturing enters the post-cleaning tank to remove the residual organic matter and ensure the cleanliness of the silicon wafer surface, thereby improving the battery conversion efficiency to a certain extent. After immersion in the loaded silicon wafer, clean it, add pure water to the tank, and add an appropriate amount of NaOH solution or cleaning solution (NaOH concentration is expected to be 0.6%, H2O2 concentration is expected to be 1.5%) according to the ratio for high-temperature cleaning (60 °C). After cleaning, clean water is carried out. Pure water cleaning is all overflow immersion cleaning, carried out at room temperature.
4) Pickling
After post-cleaning, dilute acid solution (3.15% HCl and 7.1% HF) is required for high-purity cleaning, the role of HCl is to neutralize the residual NaOH, the role of HF is to remove the oxide layer on the surface of the silicon wafer to make the surface of the silicon wafer more hydrophobic, forming a complex of silicon H2SiF6, through the complexation with metal ions to separate metal ions from the surface of the silicon wafer, so that the metal ion content of the silicon wafer is reduced, in preparation for diffusion and junction. Pure water cleaning is carried out after pickling.
The chemical reactions that occur during the pickling process are as follows:
HCl+NaOH=NaCl+H2O
SiO2+6HF=H2SiF6+2H2O
The working temperature of the pickling tank is normal temperature, and the control pickling time is 120s.
5) Slow lifting pre-dehydration
Purpose: Pre-dewatering the surface of crystalline silicon wafers, usually as the last step in the pure water cleaning process.
The crystalline silicon wafer cleaned by pure water is transferred to the slow pull groove, and the silicon wafer is first immersed in pure water to be completely immersed, and then slowly lifted upward through the manipulator and hanging basket, and the surface tension can pull down the water film on the silicon wafer.
The slow pull groove is composed of a cleaning tank and a slow pull mechanism, which is semi-closed. There is a serrated overflow port in the cleaning tank, and the clean water continuously washes away the sewage of the cleaning tank during work, keeping the water quality of the cleaning tank clean, so as to achieve the cleaning effect; When the water is kept clean, no water droplets will appear on the working surface under the action of slow pulling, and there will be no watermark when drying.
6) Tumble dry
The crystalline silicon wafer is transferred to the drying tank, and the hot air at 90 °C is blown up and down the silicon wafer for drying, and the drying is electrically heated.
In the above texturing process, the pre-cleaning and alkali texturing process will produce high-concentration alkaline wastewater containing sodium hydroxide (W1, W3, W5) and general alkaline cleaning wastewater (W2, W4, W6), and the pickling process will produce high-concentration acidic wastewater (W7) containing hydrochloric acid and hydrofluoric acid and general acidic cleaning wastewater (W8, W9). The above operation is carried out in a closed texturing machine, and the pickling process will volatilize acid waste gas (G1) containing HF and HCl, which is collected by the pipeline and sent to the acid waste gas scrubber for treatment.
Boron diffusion
The purpose of the diffusion process is to form a PN junction on the silicon wafer to realize the conversion of light energy into electrical energy. PN junction manufacturing equipment is a diffusion furnace, the project uses gaseous boron trichloride to diffuse the silicon wafer in the diffusion furnace, and the boron atoms enter the silicon wafer through diffusion, and at the same time form a layer of borosilicate glass on the surface of the silicon wafer. The main reaction equation is:
4BCl3+3O2→2B2O3+6Cl2↑
2B2O3+3Si→3SiO2+4B
The diffusion furnace is a closed negative pressure equipment, equipped with air inlet and outlet, using electric heating, and the equipment comes with an oil-free dry mechanical vacuum pump. The specific process is: first pass a large flow of N2 to drive away the air in the diffusion furnace quartz tube, and heat up the diffusion furnace, wait for the furnace temperature to rise to 1050 °C and constant, put the wafer into the quartz boat, send it to the furnace mouth for preheating for 20 minutes, and then push into the constant temperature zone, first introduce oxygen, and then introduce boron trichloride for diffusion, the overall process time is 180 minutes. During the reaction, both Si and O2 were excessive, BCl3 was completely reactiond, and C12 was produced in the reaction. After the reaction is completed, the N2 emptying equipment is used and the material is automatically discharged.
Analysis of pollution production link: The main pollution link of this process is the diffusion link after the reaction to generate chlorine (G2) mixed with residual oxygen, nitrogen, etc., which is collected by a special tube, sent to the acid waste gas scrubber for treatment, collected by the pipeline and sent to the acid waste gas scrubber for treatment.
SE laser redoping
Laser doping technology is a heavy doping of the metal gate (electrode) in contact with the silicon wafer, while light doping (low concentration doping) is maintained outside the electrode. By thermal diffusion, pre-diffusion is carried out on the surface of the silicon wafer to form light doping; At the same time, the surface BSG (borosilicate glass) is used as a local laser redoping source, and through the local thermal effect of the laser, the atoms in BSG rapidly diffuse into the silicon wafer for the second time, forming a local redoping region.
The SE laser process produces dusty exhaust gases (G3), which are treated by the machine's own dust collector and discharged through the roof exhaust system of the workshop (height approx. 15 meters).
Post-oxidation
Where the surface of the silicon wafer has been treated by laser SE, the oxide layer on the boron diffusion surface (into the glossy surface) is destroyed by the spot energy of the laser. When alkali polishing etching, an oxide layer is required as a mask layer to protect the phosphorus diffusion surface (into the glossy surface) of the silicon wafer. Therefore, oxide repair of the surface scanned by laser SE is required.
In this project, the SiO2 oxide layer was prepared by thermal oxygen oxidation. The entire oxidation process is carried out in an oxidation furnace, which is a closed atmospheric pressure equipment and is heated by electricity. First, the automatic sheet loader is used to load the silicon wafer onto the quartz boat, and then the automatic manipulator places the quartz boat on the silicon carbide cantilever slurry of the oxidation furnace, and the silicon carbide paste sends the quartz boat loaded with silicon wafers into the high-temperature quartz furnace tube. After the quartz boat enters the furnace tube, the furnace door is closed, the oxidation program is started, and the oxidation furnace runs automatically. The main chemical reactions that occur during thermal oxidation are:
Si+O2=SiO2
O2 reacts with the surface of the silicon wafer at high temperature to form SiO2, and a certain amount of nitrogen is introduced to maintain a constant pressure in the furnace tube. Maintain a period of high temperature oxygenation, so that a certain thickness of SiO2 thin layer is formed on the surface of the silicon wafer, and the process parameters are: oxidation temperature 750 °C, nitrogen flow rate 12L/min, oxygen flow rate 5L/min, 25min oxidation time. This process produces oxidized exhaust gases (hot air) containing oxygen and nitrogen, which are discharged through the exhaust port of the oxidation furnace and then discharged through the roof heat exhaust system of the workshop.
Etching
1) Go to BSG
The silicon wafer is removed by floating on water in a chain cleaner (back contact with acid), the main component of acid is 24.5% HF, and the main chemical reaction equations include:
HF+SiO2→SiF4+H2O
SiF4+HF→H2SiF6
It is then washed with water and dried by a wind knife before entering the next process. The equipment of the BSG cleaning machine is a semi-sealed equipment, which integrates acid tank and pure water cleaning tank, and is equipped with a induced draft system to form a micro-negative pressure environment in the equipment to collect volatile gases.
The main pollution in this link includes acid exhaust gas (G4) containing HF, which is collected by pipelines and sent to acid exhaust gas scrubbers for treatment. and highly concentrated acid wastewater containing hydrofluoric acid (W10) and general acid cleaning wastewater (W11).
2) Back etching
In order to improve the reflectivity of the back of the silicon wafer, the back of the silicon wafer is polished by alkali and polishing agent.
The alkali polishing section (6 lines) includes pre-cleaning-water washing-alkali polishing*2-hydrogen peroxide cleaning (reserved)-micro-texturing (reserved)-pure water cleaning-post-cleaning-pure water cleaning-pickling*2-pure water washing after pickling-slow lifting, pre-dehydration-drying *5 and other modules. The whole operation process of back etching is carried out automatically, the use of conveyor arm to send the pre-cleaned silicon wafer to the feeding place of the alkali throwing machine, the silicon wafer in the automatic closed alkali throwing machine through the roller through each corrosion, cleaning tank, equipment automatic control to supplement the acid, lye and pure water in each module, the acid and lye in the tank are pumped in through the pipeline, and the wastewater in the tank is regularly discharged.
3) Pre-cleaning
After processing, the silicon wafer enters the cleaning tank to remove the residual organic matter and ensure the cleanliness of the silicon wafer surface, thereby improving the cell conversion efficiency to a certain extent. The loaded silicon wafer is immersed in pre-cleaning, pure water is added to the tank, and an appropriate amount of NaOH solution or cleaning solution (NaOH concentration is expected to be 0.39%, H2O2 concentration is expected to be 0.61%) is added according to the ratio for high-temperature cleaning (60 °C). Pure water cleaning after pre-cleaning. Pure water cleaning is all overflow immersion cleaning, carried out at room temperature for 100s.
4) Alkali throwing
The alkali throwing tank is equipped with pure water, and an appropriate amount of NaOH solution and polishing additives are added (about 1.6% of NaOH solution, 0.97% of polishing agent concentration), and then the back surface of the silicon wafer is polished at an operating temperature of 65 °C. Alkali throwing is followed by pure water cleaning. The chemical reactions that occur during the alkali throwing process are as follows:
Si+2NaOH+H2O=Na2SiO3+2H2↑
The working temperature of the alkali throwing tank is 65°C, and the control alkali throwing time is 220s.
5) Post-cleaning and micro-texturing
Pure water was added to the tank, and an appropriate amount of NaOH solution and hydrogen peroxide (about 0.55% of NaOH solution, 0.25% of hydrogen peroxide concentration) were added according to the proportions for room temperature cleaning. After cleaning, pure water cleaning is carried out.
The chemical reactions that occur during the micro-texturing process are as follows:
Si+2NaOH+H2O=Na2SiO3+2H2↑
6) Pickling
After cleaning, dilute acid solution (0.9% HCl and 0.23% HF) is required for high-purity cleaning, the role of HCl is to neutralize the residual NaOH, the role of HF is to remove the oxide layer on the surface of the silicon wafer to make the surface of the silicon wafer more hydrophobic, forming a complex of silicon H2SiF6, through the complexation with metal ions to separate the metal ions from the surface of the silicon wafer, so that the metal ion content of the silicon wafer is reduced, in preparation for diffusion and junction. Pure water cleaning is carried out after pickling.
The chemical reactions that occur during the pickling process are as follows:
HCl+NaOH=NaCl+H2O
SiO2+6HF=H2SiF6+2H2O
The working temperature of the pickling tank is normal temperature, and the control pickling time is 100s.
7) Tumble dry
The slow-lifting pre-dehydrated crystalline silicon wafer is transferred to the drying tank, and the silicon wafer is blown up and down with hot air at 90 °C for drying, and the drying adopts electric heating.
In the above back etching process, the pre-cleaning, alkali throwing and post-cleaning processes will produce high-concentration alkaline wastewater containing sodium hydroxide (W12, W14, W16) and general alkaline cleaning wastewater (W13, W15, W17), and the pickling process will produce high-concentration acidic wastewater (W18) containing hydrochloric acid and hydrofluoric acid and general acidic cleaning wastewater (W19, W20). The above operation is carried out in a closed alkali blaster, and the pickling process will volatilize acid waste gas (G5) containing HCl and HF, which is collected by the pipeline and sent to the acid waste gas scrubber for treatment.
POPAID deposition is doped in situ
The POPAID process is a key process for plate coating prepared by integrating tunneling oxide layer and doped crystalline silicon layer.
First, the silicon wafer enters the loading cavity in the atmospheric environment, transmits into a 300° preheating chamber, and then enters the PO process cavity, at which time O2 is transported to the gas distribution block through the trachea, and ionization is activated by the RF RF power supply into ions, and the ions oxidize on the surface of the silicon wafer to form a tunneling oxide layer; Then the silicon wafer passes through the transition and buffer cavity and is transported into the paid cavity, and the paid source deposits a certain thickness of amorphous silicon on the back of the substrate, and at the same time, PH3 gas is introduced during the deposition process, and gaseous phosphorane enters the machine. Through 10kev and 0.5-2kev high-voltage radio frequency to excite the phosphorus in the phosphorus into the state of phosphorus ions, a DC high voltage is added between the ion source and the ground, so that the phosphorus ions obtain energy through the high-voltage electric field, the width of the beam is 420mm, and then the silicon wafer is transmitted below the beam, and the atoms of the paid source carry P ions or react with P ions during the flight to the substrate to achieve in situ phosphorus doping.
The main reaction equation is: PO+PAID=POPAID
Plasma oxidation (PO): SiH4+O2→SiO2
Plasma-assisted in situ doping (PAID): Si (source) + PH3→n-Si
After the completion of the reaction, it was purged with nitrogen, and the ion implantation came with adsorbent, the treatment efficiency could reach 100%, the phosphorane concentration before entering the adsorption tower was 179.05ppm, and PH3 was not detected after adsorption. This project intends to connect this exhaust gas to the DA003 exhaust gas tower for treatment and drain, and the company plans to install an automatic alarm for phosphorane leakage, with a detection limit of 0.1mg/m3.
Analysis of pollution production links: The main pollution links of this process are Ar, PH3 and N2 introduced during the process, which are collected by special pipes and sent to the acid waste gas scrubber for treatment.
anneal
The silicon wafer is placed in a reaction tube made of quartz glass, and the reaction tube is heated with a resistance wire heating furnace at a certain temperature (the commonly used temperature is 900~1200 °C, which can be reduced to below 600 °C under special conditions), and when oxygen passes through the reaction tube, a chemical reaction occurs on the surface of the silicon wafer:
Si (solid) + O2 (gaseous) → SiO2 (solid)
The redistribution of impurities generated by the annealing process also plays a role in impurity absorption, and the adsorption and fixation of sodium and potassium ions by PSG are used to remove these harmful ions.
Analysis of pollution production link: The main pollution link of this process is residual oxygen and nitrogen in the hot oxygen link.
BOE cleaning
BOE (5-line) trough equipment is an integrated semi-closed equipment, and the silicon wafer is placed in the basket by the automation equipment and converted in each tank solution in the equipment through the robotic arm. Among them, the chemical tank is constantly replenished with corresponding chemicals according to the concentration of the solution, and the whole is replaced regularly. The replaced waste liquid is discharged into the wastewater system and finally into the sewage treatment station for treatment. The water washing tank is cleaned with purified water, and when there are silicon wafers in the sink, the purified water is slowly added, and the saline wastewater automatically overflows to the wastewater collection system, and finally enters the sewage treatment station for treatment. All chemicals are liquid and are automatically dispensed by diaphragm pumps. The cleaning sequence is: pickling tank *2, water washing, post-pickling (HCL/HF/DI), water washing, slow lifting, drying *6, tank size 720L.
1) Pickling
It is necessary to use dilute acid solution (3.15% HCl and 7.1% HF) for high-purity cleaning, the role of HCl is to use Cl- complexed metal ions, the role of HF is to remove the oxide layer on the surface of the silicon wafer to make the surface of the silicon wafer more hydrophobic, forming a complex of silicon H2SiF6, through the complexation with metal ions to separate metal ions from the surface of the silicon wafer, so that the metal ion content of the silicon wafer is reduced, HF pickling 150s to remove the BSG on the front and the PSG layer on the back, Pure water cleaning is carried out after pickling.
HF+SiO2→SiF4+H2O
SiF4+HF→H2SiF6
2) Pickling after pickling
After post-cleaning, it is necessary to use dilute acid solution (14.7% HF) for high-purity cleaning, the function of HF is to remove the oxide layer on the surface of the silicon wafer to make the surface of the silicon wafer more hydrophobic, forming a complex of silicon H2SiF6, and detach the metal ions from the surface of the silicon wafer through the complexation with metal ions, so that the metal ion content of the silicon wafer is reduced.
The chemical reactions that occur during the pickling process are as follows: SiO2+6HF=H2SiF6+2H2O
The working temperature of the pickling tank is normal temperature, and the control pickling time is 100s.
3) Tumble drying
The slow-lifting pre-dehydrated crystalline silicon wafer is transferred to the drying tank, and the silicon wafer is blown up and down with hot air at 90 °C for drying, and the drying adopts electric heating.
The above pickling process will produce high-concentration acidic wastewater containing HCl, hydrofluoric acid (W21) and high-concentration acidic wastewater containing hydrofluoric acid (W23), and general acidic cleaning wastewater (W22, 24, 25). The above operation is carried out in a closed cleaning machine, and the pickling process will volatilize acid exhaust gas (G6) containing HCl and HF and acid waste gas containing HF (G7), which are collected by pipelines and sent to acid waste gas scrubbers for treatment.
ALD
ALD equipment is used to coat the surface of the silicon wafer with an Al2O3 layer to improve the passivation and impurity absorption effect on the surface of the silicon wafer. It mainly uses gaseous Al(CH3)3 to react with water vapor (H2O) to form Al(OH)3, which attaches to the surface of silicon wafers and produces methane gas.
The main reaction equation is:
Al(CH3)3+3H2O→Al(OH)3+3CH4↑
2Al(OH)3→Al2O3+3H2O↑
ALD equipment is a closed negative pressure equipment, equipped with air inlet, outlet, inlet and outlet, heating is electric heating, the equipment comes with oil-free dry mechanical vacuum pump. After the start of production, the robot arm first feeds the cells into the ALD equipment and closes the material opening. Heat to a certain temperature, vacuum to make the pressure in the equipment meet the production needs. The deposited film AL2O3 is generated by alternating pulses of the gas-phase precursor TMA and H2O into the reaction chamber and chemically adsorbed on the deposition matrix. Finally, after replacing the methane exhaust gas in the equipment through nitrogen, turn on the equipment and automatically remove the silicon wafer.
The main pollutant in this link is exhaust gas methane (G8), which is pumped out by vacuum pump and treated by stainless steel silane combustion cylinder + water spray device.
Front coating
The basic principle is to use high-frequency photodischarge to generate plasma to influence the thin film deposition process, promote the decomposition, chemistry, excitation and ionization of gas molecules, and promote the formation of reactive groups. Since the presence of NH3 is conducive to the flow and diffusion of active groups, the growth rate of the film is improved, and the deposition temperature is greatly reduced.
The main chemical reactions that occur during the deposition of silicon oxide film by PECVD are:
SiH4+NH3+N2O→xSi2O2N4+N2↑+yH2↑
PECVD positive film equipment is a closed negative pressure equipment, electric heating, with oil-free dry mechanical vacuum pump. During production, first fill the equipment with nitrogen, the robotic arm completes the silicon wafer loading boat, after the external pressure in the equipment reaches the inlet, open the inlet and outlet port, the graphite boat automatically enters the equipment, and closes the inlet and outlet. Vacuuming and carrying out various safety inspections, after confirming safety, silane and ammonia are introduced to complete the silicon oxide coating in the equipment. After the coating is completed, the residual gas in the special gas pipeline and equipment is discharged through nitrogen, and then the inlet and outlet are opened and the material is discharged. After cooling, it enters the finishing and enters the subsequent process.
Analysis of pollution production links: The main pollution form of the production process is coating waste gas (silane, excessive laughing gas, excessive ammonia, hydrogen, nitrogen, etc.) (G9), which first enters the stainless steel silane combustion cylinder through the induced draft air system, and then discharges it after treatment through the spray tower.
Coating on the back
The main chemical reactions that occur during the deposition of silicon oxide film by PECVD are:
SiH4+NH3+N2O→xSi2O2N4+N2↑+yH2↑
PECVD backing film equipment is closed negative pressure equipment, electric heating, with oil-free dry mechanical vacuum pump. During production, first fill the equipment with nitrogen, the robotic arm completes the silicon wafer loading boat, after the external pressure in the equipment reaches the inlet, open the inlet and outlet port, the graphite boat automatically enters the equipment, and closes the inlet and outlet. Vacuuming and carrying out various safety inspections, after confirming safety, silane and ammonia are introduced to complete the silicon oxide coating in the equipment. After the coating is completed, the residual gas in the special gas pipeline and equipment is discharged through nitrogen, and then the inlet and outlet are opened and the material is discharged. After cooling, it enters the finishing and enters the subsequent process.
Analysis of pollution production links: The main pollution form of the production process is coating waste gas (silane, excessive laughing gas, excessive ammonia, hydrogen, nitrogen, etc.) (G9), which first enters the stainless steel silane combustion cylinder through the induced draft air system, and then discharges it after treatment through the spray tower.
Metallization
1) Printing
During the printing process, the slurry is above the screen, and the scraper is pressed on the screen plate with a certain pressure, so that the screen deformation contacts the surface of the silicon wafer. The slurry is extruded to contact the surface of the silicon wafer; The surface adsorption force of the silicon wafer is large, and the slurry is snatched out of the mesh. At this time, the scraper is running, and the previously deformed mesh plate is under the action of good recovery force, so that the slurry falls smoothly on the surface of the silicon wafer. Among them, silver paste is a paste printing paste made of ultra-fine and high-purity silver and aluminum powder as the main metal, with a certain amount of organic binder and resin as auxiliary agents.
First of all, back electrode printing and drying: accurately position the printed back electrode paste (including laser punching position) (silver paste) on the back of the battery, and quickly dry at low temperature to ensure that the printed back electrode is not damaged when printing in the next step.
Secondly, the back side fine grid line printing, drying: on the back of the battery to accurately position the printing fine grid line paste (silver paste), and quickly dry at low temperature, the main purpose is to contact with the silicon matrix, transmit current, and re-dope, reduce carrier recombination, increase boost.
Then pass through the flipper, and the battery sheet turns from the back to the front up. Positive electrode printing and drying: Accurately position the printed positive electrode paste (silver paste) on the front of the battery, and dry quickly at low temperature, the main function is to conduct and transmit the current collected by the thin grid line to an external circuit or memory.
Finally, the front side fine grid line printing, drying: on the front of the battery accurately position the paste (silver paste) printed front electrode, after printing, wait to enter the sintering furnace solid sintering, form a good ohmic contact, the main function is to collect current, increase the light absorption capacity of the battery sheet, improve the conversion efficiency.
The drying temperature of the slurry in the above drying process is about 200 °C. This process produces organic volatile gas (G10), and the main pollution factor is alcohol ester twelve, measured by VOCs. The organic waste gas generated by the printing process is collected by the gas collection hood, adsorbed and treated by a 2-stage tandem activated carbon adsorption box, and finally discharged through the exhaust cylinder. The exhaust duct needs to be cleaned and cleaned regularly to maintain its absorption efficiency.
2) Sintering
Sintering is to sinter the main fine grid paste printed on the silicon wafer into a battery sheet at high temperature, so that the electrode is embedded in the surface to form a firm mechanical contact and a good electrical connection, and finally the electrode and the silicon wafer itself form ohmic contact.
The printed silicon wafer is sintered using a sintering furnace (electric heating), the sintering furnace is divided into different temperature zones, the silicon wafer forms upper and lower electrodes during the sintering process, and the maximum temperature of sintering is 700~800 °C. In this process, the organic solvent alcohol ester in the slurry is completely volatilized to form organic waste gas (G11), which is measured by VOCs, and then fully burned by the high-temperature combustion tower device with the equipment and then adsorbed by a 2-stage series activated carbon adsorption box with the printing waste gas, and discharged through the exhaust cylinder after adsorption.
3) Electric injection
After the cell is sintered, the method of direct electrical injection of carriers (reverse injection of direct current) is used to change the charged state of hydrogen in the silicon body, so as to well passivate the decaying boron-oxygen complex, transform it into a stable reecology, and finally achieve the purpose of anti-photodecay.
Test the packaging
After the solar cell is fabricated, the electrical performance parameters of the solar cell (such as measuring its I-V curve and light slew rate, etc.) are tested using a test instrument. After the test is completed, the battery will be automatically divided into multiple gears according to certain standards. When the number of cells in a certain gear reaches the specified number, the equipment will remind the operator to take it out and pack it. The device also features debris detection, which rejects debris when it is found, rather than testing it as a complete battery, a process that produces a waste cell (S2).
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