CN110438571A - A kind of efficient monocrystalline process for etching and its equipment - Google Patents

Abstract

The invention discloses a high-efficiency single crystal texturing process, which comprises the following steps: removing damaged layer, alkali texturing, acid texturing, alkali washing, pickling, slow pulling, and discloses the equipment for realizing the process. The invention has the advantages that: the cashmere making process combines alkali cashmere and acid cashmere to produce suede, forming a suede with uniform suede and low reflectivity, and has a good suede effect; the process has strong operability, High reliability, low cost, and can improve the electrical performance and appearance of the cell, especially in quasi-single crystal texturing, which has unique advantages; the texturing equipment can be modified from the traditional single crystal texturing equipment, and the production efficiency is high , high degree of automation, environmental protection, effectively realize the texturing process, and provide an effective way for the production of quasi-single crystal cells.

Description

A high-efficiency single crystal texturing process and its equipment

technical field

The invention relates to the manufacture of solar polycrystalline silicon cells, in particular to a monocrystalline texturing process and equipment thereof.

Background technique

At present, monocrystalline cells in the photovoltaic industry are ushering in new opportunities for development, and major battery factories have invested in the transformation of monocrystalline routes. In the production process of monocrystalline cells, the first process is monocrystalline texturing The main function is to remove the dirty and damaged layer on the surface of the silicon wafer, and form a low-reflectivity high-quality suede surface with a light effect on the surface of the silicon wafer to improve the efficiency of the cell.

At present, single crystal texturing is mainly conventional alkali texturing, which utilizes the anisotropy of silicon wafers in alkaline solution, that is, the (111) crystal plane in silicon crystals has the slowest corrosion rate and the (100) plane has the fastest corrosion rate. After being corroded by alkaline solution, a special pyramid structure is formed. Monocrystalline silicon wafers use alkali texturing to make texture. This chemical reaction has limitations. When the pyramids on the surface of the texture are large, the reflectivity is high, which will affect the efficiency of the cell; when the pyramids on the surface of the texture are large Even though the reflectivity becomes smaller, the uniformity of the textured surface is poor. The uniformity of the textured surface directly affects the coating effect of the silicon wafer, the uniformity of the PN junction, and the spectral response of the cell. Therefore, how to improve the uniformity of the textured surface , while reducing the reflectivity has become the current technical bottleneck.

On the other hand, the existing single crystal texturing machine can only carry out alkali texturing, which has limitations, and the single crystal textured surface prepared by this method is not easy to control, and the textured surface on the surface of the silicon wafer is easy to be too large (that is, the texture of the silicon wafer is too large). The problem of high reflectivity) or uneven texture affects the conversion efficiency and appearance of the cell, especially in the texture of quasi-single crystal silicon wafers, and its defects are more prominent. If only alkali texturing is used for quasi-single crystal texturing, the uniformity of appearance will be significantly different, especially for the poor coverage of surface defects of quasi-single crystal silicon wafers.

At present, quasi-single crystals are rapidly developing due to their cost advantages. Therefore, there is an urgent need for single crystal texturing equipment capable of producing high-quality textured surfaces, so as to prepare low-cost, efficient and beautiful cells.

Contents of the invention

Purpose of the invention: In view of the above problems, one of the purposes of the present invention is to provide a single crystal texturing process to improve the texturing effect, especially to be applicable to quasi-single crystal texturing, and to improve the performance and appearance of the battery sheet. Another aspect of the present invention One purpose is to provide equipment for realizing this single crystal texturing process.

Technical solution: a high-efficiency single crystal texturing process, including the following steps:

Step 1, remove the damaged layer: immerse the silicon wafer in the mixed solution A containing NaOH and H ₂ O ₂ to react, and then rinse with pure water. In the mixed solution A, the mass concentration of NaOH is 2g/L-2.5g/L , the volume fraction of H ₂ O ₂ is 4% to 5%, the reaction temperature is 60°C to 70°C, and the reaction time is 100S to 170S;

Step 2, alkali texturing: the silicon wafer obtained in step 1 is immersed in the mixed solution B containing NaOH and monocrystalline silicon texturing additives to react, and then rinsed with pure water. In the mixed solution B, the mass concentration of NaOH is 15g/ L～17g/L, the volume fraction of monocrystalline silicon texturing additive is 0.6%～0.8%, the reaction temperature is 75℃～85℃, and the reaction time is 600S～800S;

Step 3, acid velvet:

Step 301, immerse the silicon wafer obtained in step 2 in a mixed solution C containing HF, HNO ₃ , and AgNO ₃ for reaction, and then rinse with pure water. In the mixed solution C, the volume fraction of HF is 20% to 30%, and the HNO The volume fraction of ₃ is 12%~16%, the mass concentration of AgNO ₃ is 0.04g/L~0.06g/L, the reaction temperature is 25℃~29℃, and the reaction time is 60S~100S;

Step 302, immerse the silicon wafer obtained in step 301 in solution D containing HNO ₃ for cleaning, and then rinse with pure water. In solution D, the volume fraction of HNO ₃ is 30% to 60%, and the cleaning temperature is 40° C. to 50° C. ℃, cleaning time is 90S～150S;

Step 303, immersing the silicon wafer obtained in step 302 in the mixed solution E containing HF and _HNO3 for reaction, and then rinsing with pure water. In the mixed solution E, the volume fraction of HF is 15% to 25%, and the volume fraction of _HNO3 The fraction is 12%~15%, the reaction temperature is 25℃~32℃, and the reaction time is 50S~80S;

Step 4, alkali cleaning: immerse the silicon wafer obtained in step 303 in solution F containing KOH for cleaning, and then rinse with pure water. In solution F, the volume fraction of KOH is 2% to 3%, and the cleaning temperature is 25°C to 30℃, cleaning time is 30S～50S;

Step 5, pickling: immerse the silicon wafer obtained in Step 4 in the mixed solution G containing HCl and HF for cleaning, and then rinse with pure water. In the mixed solution G, the volume fraction of HCl is 15% to 25%, and the volume fraction of HF is The volume fraction is 8%~15%, the cleaning temperature is room temperature, and the cleaning time is 30S~50S;

Step 6, slow pulling: immerse the silicon wafer obtained in step 5 in pure water for slow pulling.

Further, the HF described in step 301, step 303, and step 5 are all HF solutions with a mass concentration of 49%, and the _HNO3 described in step 301, step 302, and step 303 are all HNO with a mass concentration of 68%. ₃ solutions, the HCl described in step 5 is a HCl solution with a mass concentration of 38%, and the KOH described in step 4 is a KOH solution with a mass concentration of 48%.

Further, the pure water rinsing in step 1 is rinsing with pure water at 60°C to 70°C for 80S to 120S, and the pure water rinsing in step 2 is rinsing with pure water at 55°C to 65°C for 100S to 150S , the pure water rinsing described in step 301 is rinsing with pure water for 30S-80S at room temperature, the pure water rinsing described in step 302 is rinsing with pure water for 30S-50S at room temperature, the pure water described in step 303 The water rinsing is rinsing with pure water at room temperature for 30S-80S, the pure water rinsing described in step 4 is rinsing with pure water for 30S-80S at room temperature, and the pure water rinsing described in step 5 is at room temperature with pure water. Rinse with water for 30S ~ 80S.

Further, the temperature of the pure water in step 6 is 60°C-70°C, and the slow pulling time is 30S-50S.

Further, the cleaning described in step 302 is at least two levels of cleaning tanks for sequential cleaning, each level of cleaning tank contains solution D, and the cleaning solution in the next level of cleaning tank is returned to the upper level of cleaning tank.

The principle of the texturing process of the present invention is: on the one hand, it reduces the stains on the surface of the silicon chip; Nano-micron holes form anti-reflection for incident light, further reduce the reflectivity of the suede surface, and increase the transmission effect, which can not only improve the uniformity of PN junction and coating, but also increase the absorption of photons by silicon cells, and further improve photoelectric conversion. efficiency and improve the electrical performance of monocrystalline silicon cells.

A device for realizing the above-mentioned high-efficiency single crystal texturing process, including a feeding device, an ultrasonic cleaning tank, a water tank A, a single crystal alkali texturing tank, a water tank B, an acid texturing tank, and a water tank sequentially connected according to the silicon wafer conveying direction C, pickling silver removal tank, water tank D, pickling modification tank, water tank E, alkali washing tank, water tank F, pickling tank, water tank G, slow pulling tank, feeding device, the ultrasonic cleaning tank provides NaOH and H ₂ O ₂ mixed liquid A, the single crystal alkali texturing tank provides a mixed liquid B containing NaOH and monocrystalline silicon texturing additives, and the acid texturing tank provides a mixed liquid containing HF, HNO ₃ , AgNO ₃ Solution C, the pickling tank for removing silver provides solution D containing HNO ₃ , the _acid washing modification tank provides HF and HNO mixed solution E, the alkali cleaning tank) provides solution F containing KOH, the The pickling tank provides a mixture G containing HCl and HF.

Further, it also includes a mechanical arm gripper for transferring silicon wafers.

Further, the ultrasonic cleaning tank, water tank A, single crystal alkali texturing tank, water tank B, acid texturing tank, pickling desilvering tank, pickling modification tank, alkali cleaning tank, pickling tank, slow pulling tank Heating devices and temperature detectors are installed on the tank body to control the liquid temperature in the tank body; the ultrasonic cleaning tank (2), single crystal alkali texturing tank (4), acid texturing tank (6), pickling Above the liquid level, exhaust devices are provided in the tank bodies of the silver removal tank, pickling modification tank, alkali washing tank, and pickling tank; ultrasonic generators are installed on the tank bodies of the ultrasonic cleaning tank and water tank A.

Further, at least two independent tanks for pickling and removing silver are provided, and each tank body is provided with an overflow port, and the liquid after pickling in the latter tank body enters the previous tank through the overflow port on it. In the body, the liquid after pickling in the first tank body overflows out of the tank body through the overflow port on it.

Further, the acid-texturing tank and the pickling finishing tank are equipped with external heat exchangers and chillers, and the liquid in the tanks exchanges heat with the chillers through the heat exchangers.

Beneficial effect: compared with prior art, the advantage of the present invention is:

1. The cashmere-making process of the present invention makes the suede surface through the combination of alkali-made suede and acid-made suede, forming a suede with uniform suede and low reflectivity, and has a good suede effect; the process is highly operable and reliable High reliability, low cost, and can improve the electrical performance and appearance of the cell, especially in quasi-single crystal texturing, which has unique advantages;

2. The texturing equipment of the present invention can be modified on the traditional single crystal texturing equipment, with high production efficiency, high degree of automation, environmental protection, effectively realize the texturing process, and provide an effective way for the production of quasi-single crystal cells.

Description of drawings

Fig. 1 is a block diagram of equipment structure of the present invention;

Fig. 2 is the structural representation of ultrasonic cleaning tank;

Fig. 3 is the structural representation of tank A;

Fig. 4 is the structural representation of single crystal alkali cashmere making groove;

Fig. 5 is the schematic diagram of the acid cashmere tank structure;

Fig. 6 is the schematic diagram of pickling silver tank structure;

Fig. 7 is a schematic diagram of the structure of the pickling modification tank.

Detailed ways

The present invention will be further explained below in conjunction with the accompanying drawings and specific embodiments. These examples are only for illustrating the present invention and are not intended to limit the scope of the present invention.

Example 1

A high-efficiency single crystal texturing process, comprising the following steps:

Step 1, remove the damaged layer: immerse the silicon wafer in the mixed solution A containing NaOH and H ₂ O ₂ at 65°C for 100 seconds to remove the stain and damaged layer on the surface of the silicon wafer. In the mixed solution A, the mass concentration of NaOH is 2.2g/L, the volume fraction of H ₂ O ₂ is 4.4%. After the reaction, the silicon wafer is immersed in pure water at 65°C and rinsed for 100S to perform secondary cleaning on the silicon wafer.

Step 2, alkali texturing: immerse the silicon wafer obtained in step 1 in the mixed solution B containing NaOH and monocrystalline silicon texturing additive (Sanfeng MQT-330B6) at 80°C for 700 seconds, and then texture the surface of the silicon wafer to form pyramid texture To reduce the reflectivity of the textured surface, in the mixed solution B, the mass concentration of NaOH is 16.7g/L, and the volume fraction of monocrystalline silicon texturing additive is 0.7%. After the reaction, immerse the silicon wafer in pure water at 60°C Rinse for 100S to remove the residual liquid on the surface of the silicon wafer.

Step 3, acid velvet:

In step 301, immerse the silicon wafer obtained in step 2 in the mixed solution C containing HF, HNO ₃ , and AgNO ₃ at 28°C for 70 seconds, and form nano-micron corrosion pits on the pyramid textured surface of the silicon wafer, further reducing the thickness of the silicon wafer surface. Reflectance, in the mixed solution C, the volume fraction of HF is 25%, the volume fraction of _HNO3 is ₁₅ %, the mass concentration of AgNO3 is 0.05g/L, after the reaction, the silicon wafer is immersed in pure water at room temperature Rinse for 40S to remove the residual liquid on the surface of the silicon wafer.

Step 302, immerse the silicon wafer obtained in step 301 in a solution D containing _HNO3 at 45°C for cleaning, and remove the metal Ag particles in the nanometer pores on the surface of the silicon wafer. In solution D, the volume fraction of _HNO3 is 40% , where at least two levels of cleaning tanks are set to clean in sequence, and each level of cleaning tanks is initially filled with solution D. Taking the setting of three levels of cleaning as an example, the cleaning time of each level of cleaning tanks is 40S, and the next The cleaning solution in the first-level cleaning tank is returned to the upper-level cleaning tank, and after being cleaned by the third-level cleaning tank, the silicon wafer is immersed in pure water and rinsed at room temperature for 40S to remove the residual liquid on the surface of the silicon wafer.

Step 303, immerse the silicon wafer obtained in step 302 in the mixed solution E containing HF and _HNO3 at 28°C and react for 50 seconds, and modify the nano-micropores on the surface of the pyramid. In the mixed solution E, the volume fraction of HF is 18%, and the volume fraction of HNO ₃ is 13%. After the reaction, the silicon wafer is immersed in pure water and rinsed for 40S at room temperature to remove the residual liquid on the surface of the silicon wafer.

Step 4, alkali cleaning: immerse the silicon wafer obtained in step 303 in solution F containing KOH at 28°C for 40 seconds to remove residual acid on the surface of the silicon wafer, and lightly polish the surface of the silicon wafer. In solution F, KOH The volume fraction of the silicon wafer is 2.2%. After cleaning, the silicon wafer is immersed in pure water and rinsed for 40S at room temperature to remove the residual liquid on the surface of the silicon wafer.

Step 5, pickling: immerse the silicon wafer obtained in step 4 in the mixed solution G containing HCl and HF and wash it for 40 seconds at room temperature to remove residual alkali and metal ions on the surface of the silicon wafer. In the mixed solution G, the volume of HCl The fraction is 20%, and the volume fraction of HF is 12%. After cleaning, immerse the silicon wafer in pure water and rinse it for 40S at room temperature to remove the residual liquid on the surface of the silicon wafer.

Step 6, slow pulling: immerse the silicon wafer obtained in step 5 in pure water at 65°C for 40 seconds to perform slow pulling.

The HF in step 301, step 303, and step 5 is the HF solution that mass concentration is 49%, and the HNO in step 301, step 302, and step 303 is the HNO that mass concentration is 68 _% Solution, in step ₅ HCl is a HCl solution with a mass concentration of 38%, and KOH in step 4 is a KOH solution with a mass concentration of 48%.

The equipment for realizing the above-mentioned high-efficiency single crystal texturing process, as shown in Figure 1, includes a feeding device 1 composed of a feeding machine 101 and a feeding transfer table 102, and consists of a feeding machine 1701 and a feeding transfer table 1702 The blanking device 17 is composed of ultrasonic cleaning tank 2, water tank A3, single crystal alkali texturing tank 4, water tank B5, acid texturing tank 6, water tank C7, pickling silver removal tank 8, water tank D9, pickling modification tank 10. The tank body station module composed of water tank E11, alkali washing tank 12, water tank F13, pickling tank 14, water tank G15, and slow lifting tank 16 has a mechanical arm movement module with a mechanical arm gripper 18. According to the conveying direction of silicon wafers, feeding machine 101, feeding conveyor 102, ultrasonic cleaning tank 2, water tank A3, single crystal alkali texturing tank 4, water tank B5, acid texturing tank 6, water tank C7, pickling and silver removal Tank 8, water tank D9, pickling modification tank 10, water tank E11, alkali washing tank 12, water tank F13, pickling tank 14, water tank G15, slow lifting tank 16, feeding machine 1701, and feeding conveyor 1702 are connected in sequence , the gripper 18 of the mechanical arm moves laterally above each tank body, and transfers the silicon wafer to each tank body. The operation of the equipment is controlled by PLC, which controls the preparation of solutions, replenishment, etc., and processes the silicon wafers under the specified process.

When the equipment is working, the flower basket 19 with silicon chips is placed on the feeding machine. The feeding machine is equipped with an automatic straightening device and a reverse protection device. Automatically monitor whether there is a flower basket placed upside down, and is equipped with a reverse alarm function. A counting detector is installed on the feeding tank to sense the number of silicon wafers being loaded and provide a signal source for the PLC. The PLC controls the liquid replenishment in each tank according to the number of photos. , and then the flower baskets are transferred to the feeding conveyor table through the conveyor belt on the loading machine table, and then the flower baskets with silicon wafers are sequentially transferred to each tank of the tank station module by the gripper of the mechanical arm, and then the silicon wafers enter the lower The feeder table, the unloading conveyor table, and finally sent to the drying machine for drying.

Ultrasonic cleaning tank 2, water tank A3, single crystal alkali velvet tank 4, water tank B5, acid velvet tank 6, pickling silver removal tank 8, pickling modification tank 10, alkali cleaning tank 12, pickling tank 14, slow extraction Lacing tank 16 is equipped with heating device and temperature detector at the bottom of the tank body to control the liquid temperature in the tank body. Acid cashmere tank 6 and pickling finishing tank 10 are all equipped with heat exchanger and ice water machine to control the liquid temperature in the tank body. Ultrasonic generators are installed on the tank bodies of the ultrasonic cleaning tank 2 and the water tank A3. The initial liquid dosing and liquid replenishment of each tank of the tank station module adopts an automatic liquid replenishment system. Exhaust devices are installed on each tank body except the water tank in the tank station module to form an exhaust system. The exhaust devices are equipped with built-in sensors to automatically adjust the exhaust air volume. During the operation of the equipment, the exhaust device will always be in the open state, mainly to remove the acid gas and alkali gas in the equipment in time, and reduce the corrosion of the equipment by acid and alkali. The top of each tank is equipped with a cover that can be opened and closed automatically. When the gripper of the mechanical arm grabs the flower basket and reaches the top of the tank, the cover will be opened automatically. When the reaction time of the silicon wafer in the tank reaches the specified value, the cover will The board opens automatically, and at the same time, the gripper of the robotic arm takes out the flower basket and puts it into the next slot in turn. Multiple grippers of the robotic arm can be set up, corresponding to several tanks, and can work at the same time, thereby increasing production capacity.

Ultrasonic cleaning tank 2 provides mixed solution A containing NaOH and H ₂ O ₂ , and its structure is shown in Figure 2: 208 supplies alkali solution to the periphery, 209 supplies hydrogen peroxide to the periphery, 2010 supplies pure water to the periphery, and the chemical All products need to be added to the liquid replenishment tank 207 first, and then the initial liquid dosing and automatic liquid replenishment are carried out through the valve 206 and the valve 205. Enter the tank from the liquid inlet 2011, and the liquid replenishment system is equipped with a valve connected to the PLC; a heater 204 is installed at the bottom of the tank The liquid in the tank is heated, and a temperature detector 202 is provided. The temperature detector is connected to the PLC. One end of the temperature detector is installed inside the tank for temperature measurement, and the other end is connected to the PLC; an ultrasonic generator is installed on the side of the tank 2012 Ultrasonic vibration is performed on the liquid, and the ultrasonic generator is connected to the PLC; during normal production, the tank body overflows the excess liquid out of the tank body through the overflow port 201; after the life of the liquid in the tank body expires, it is discharged to the Out of the tank; an air outlet 2013 is provided above the liquid surface of the tank.

Water tank A3 performs secondary cleaning on silicon wafers, and its structure is shown in Figure 3: 301 is an overflow port, 302 is a temperature detector, a heater 303 is installed at the bottom of the tank body, 304 is for supplying pure water to the periphery, and 305 is for draining Mouth, 306 is liquid inlet, and the ultrasonic generator 307 is arranged on the tank body side.

Single crystal alkali texturing tank 4 provides mixed liquid B containing NaOH and monocrystalline silicon texturing additives, its structure is shown in Figure 4: 408 supplies alkali solution to the periphery, 409 supplies pure water to the periphery, and chemicals supplied to the periphery Both need to be added to the liquid replenishment tank 407 first, and then the initial liquid dosing and automatic liquid replenishment are carried out through the valve 406 and the valve 405. Enter the tank body from the liquid inlet 4011, and the liquid replenishment system is equipped with a valve connected to the PLC; 4010 is for supplying monocrystalline silicon texture Additives, due to the small amount, need to be added manually, and the metering pump is used for precise liquid addition, and the metering pump is connected to the PLC; 401 is the overflow port, 402 is the temperature detector, 403 is the drain port, and a heater 404 is installed at the bottom of the tank; An air outlet 4012 is arranged above the liquid surface of the tank body.

Acid texturing tank 6 provides mixed liquid C containing HF, HNO ₃ , and AgNO ₃ , and its structure is shown in Figure 5: 608 supplies HF to the periphery, 609 supplies pure water to the periphery, 6010 supplies HNO ₃ to the periphery, and supplies All the chemicals need to be added to the rehydration barrel 607 first, and then the initial liquid dosing and automatic rehydration are carried out through the valve 606 and the valve 605. Enter the tank from the liquid inlet 6015, and the rehydration system is equipped with a valve connected to the PLC; 6011 supplies AgNO to the periphery. ₃ The solution, due to the small amount, needs to be added manually, and the metering pump is used to accurately add liquid, and the metering pump is connected to the PLC; during normal production, the temperature of the liquid in the tank will gradually rise, and the temperature detector 602 will detect the liquid in the tank The temperature change is fed back to the PLC and the temperature is adjusted through it. Under the action of the circulation pump 6012, it circulates through the heat exchanger 6013, and the liquid in the tank exchanges heat with the liquid in the chiller 6014 to achieve cooling; the bottom of the tank The heater 604 is set to heat the liquid in the tank body, the temperature detector 602 is connected to the PLC, one end of the temperature detector is installed inside the tank body for temperature measurement, and the other end is connected to the PLC; during normal production, the tank body passes through the overflow port 601 The excess liquid is overflowed out of the tank; after the life of the liquid in the tank expires, it is discharged to the outside of the tank through the liquid discharge port 603; an air exhaust port 6016 is arranged above the liquid surface of the tank.

Pickling silver tank 8 can be provided with one, two, three etc. as required, pickling silver tank 8 provides solution D containing HNO ₃ , as shown in accompanying drawing 6, to set two pickling silver tanks as Example to illustrate its structure: 808, 8014 supply HNO ₃ to the periphery, 809, 8015 supply pure water to the periphery, and the chemicals supplied from the periphery need to be added to the rehydration tank 807, 8013 first, and then pass through the valves 806, 8012 and valves 805, 8011 The initial liquid dosing and automatic liquid replenishment enter the respective tanks from the liquid inlets 8017 and 8018 respectively, and the pickled liquid in the latter tank overflows into the previous tank through the overflow port 6020 for preliminary cleaning, thus saving The amount of acid used, the liquid replenishment system is equipped with a valve connected to the PLC; the bottom of the two tanks is respectively equipped with heaters 804 and 8022 to heat the liquid in the tank, and the two tanks are respectively equipped with temperature detectors 802 and 8016. The detector is connected to the PLC, one end of the temperature detector is installed inside the tank for temperature measurement, and the other end is connected to the PLC; during normal production, the previous tank overflows excess liquid out of the tank through the overflow port 801; After the life of the liquid expires, it is discharged to the outside of the tank through the liquid discharge ports 803 and 8010; air exhaust ports 8019 and 8021 are arranged above the liquid surface of the tank body.

The pickling modification tank 10 provides a mixed liquid E containing HF and HNO ₃ , and its structure is shown in Figure 7: 1008 supplies HF to the periphery, 1009 supplies pure water to the periphery, 1010 supplies HNO ₃ to the periphery, and chemicals supplied to the periphery Both need to be added to the liquid replenishment barrel 1007 first, and then the initial liquid dosing and automatic liquid replenishment are carried out through the valve 1006 and the valve 1005. Enter the tank body from the liquid inlet 1014, and the liquid replenishment system is equipped with a valve connected to the PLC; in the normal production process, the liquid in the tank body The temperature of the liquid will gradually rise, and the temperature detector 1002 will feed back the temperature change of the liquid in the tank to the PLC and adjust the temperature through it. Under the action of the circulating pump 1011, it will circulate through the heat exchanger 1012. The liquid in the water machine 1013 performs heat exchange to achieve cooling; a heater 1004 is installed at the bottom of the tank to heat the liquid in the tank, and the temperature detector 1002 is connected to the PLC, and one end of the temperature detector is installed inside the tank for temperature measurement. The other end is connected to the PLC; during normal production, the tank overflows excess liquid out of the tank through the overflow port 1001; after the liquid life in the tank expires, it is discharged to the outside of the tank through the drain port 1003; above the liquid level of the tank Air exhaust outlet 1015 is provided.

Alkaline cleaning tank 12 provides solution F containing KOH, and pickling tank 14 provides mixed solution G containing HCl and HF.

Example 2

A high-efficiency single crystal texturing process, comprising the following steps:

Step 1, remove the damaged layer: immerse the silicon wafer in the mixed solution A containing NaOH and H ₂ O ₂ at 60°C for 150 seconds to remove the stain and damaged layer on the surface of the silicon wafer. In the mixed solution A, the mass concentration of NaOH is 2.5g/L, the volume fraction of H ₂ O ₂ is 4.1%. After the reaction, immerse the silicon wafer in pure water at 60°C and rinse it for 120S.

Step 2, alkali texturing: immerse the silicon wafer obtained in step 1 in the mixed solution B containing NaOH and monocrystalline silicon texturing additive (Sanfeng MQT-330B6) at 75°C and react for 750 seconds to form a textured surface. In B, the mass concentration of NaOH is 15.3g/L, and the volume fraction of monocrystalline silicon texturing additive is 0.8%. After the reaction, the silicon wafer is immersed in pure water at 63° C. for rinsing for 100 seconds.

Step 3, acid velvet:

Step 301, immerse the silicon wafer obtained in step 2 in a mixed solution C containing HF, HNO ₃ , and AgNO ₃ at 29°C for 60 seconds. In the mixed solution C, the volume fraction of HF is 30%, and the volume fraction of HNO ₃ is 13%, the mass concentration of AgNO ₃ is 0.04g/L, after the reaction, the silicon wafer is immersed in pure water and rinsed at room temperature for 60S.

Step 302, immerse the silicon wafer obtained in step 301 in a solution D containing _HNO3 at 41°C for cleaning, and remove the metal Ag particles in the nanometer pores on the surface of the silicon wafer. In solution D, the volume fraction of _HNO3 is 34% , where three-level cleaning tanks are set to clean in sequence, each level of cleaning tank is initially filled with solution D, and the cleaning time of each level of cleaning tank is 50S, and the cleaning solution in the next level of cleaning tank can be returned to the previous level In the first-level cleaning tank, after being cleaned by the third-level cleaning tank, the silicon wafer is immersed in pure water and rinsed at room temperature for 45S.

Step 303, immerse the silicon wafer obtained in step 302 in the mixed solution E containing HF and _HNO3 at 32°C and react for 50 seconds to modify the nano-micropores on the surface of the pyramid. In the mixed solution E, the volume fraction of HF is 15 %, the volume fraction of HNO ₃ was 12%. After the reaction, the silicon wafer was immersed in pure water and rinsed at room temperature for 30S.

Step 4, alkali cleaning: immerse the silicon wafer obtained in step 303 in solution F containing KOH at 25°C and wash it for 50 seconds. In solution F, the volume fraction of KOH is 2.9%. After cleaning, immerse the silicon wafer in pure water at room temperature Rinse for 60S.

Step 5, pickling: immerse the silicon wafer obtained in step 4 in the mixed solution G containing HCl and HF and wash at room temperature for 30 seconds. In the mixed solution G, the volume fraction of HCl is 15%, and the volume fraction of HF is 14%. After cleaning, immerse the wafer in pure water and rinse it for 60S at room temperature.

Step 6, slow pulling: immerse the silicon wafer obtained in step 5 in pure water at 60° C. for 50 seconds to perform slow pulling.

The HF in step 301, step 303, and step 5 is the HF solution that mass concentration is 49%, and the HNO in step 301, step 302, and step 303 is the HNO that mass concentration is 68 _% Solution, in step ₅ HCl is a HCl solution with a mass concentration of 38%, and KOH in step 4 is a KOH solution with a mass concentration of 48%.

The equipment for realizing the high-efficiency single crystal texturing process of this embodiment is the same as that of Embodiment 1.

Example 3

A high-efficiency single crystal texturing process, comprising the following steps:

Step 1, remove the damaged layer: immerse the silicon wafer in the mixed solution A containing NaOH and H ₂ O ₂ at 70°C for 120 seconds to remove the stain and damaged layer on the surface of the silicon wafer. In the mixed solution A, the mass concentration of NaOH is 2.4g/L, the volume fraction of H ₂ O ₂ is 4.7%. After the reaction, immerse the silicon wafer in pure water at 60°C and rinse it for 100S.

Step 2, alkali texturing: immerse the silicon wafer obtained in step 1 in the mixed solution B containing NaOH and monocrystalline silicon texturing additive (Sanfeng MQT-330B6) at 85°C and react for 750 seconds to form a textured surface. In B, the mass concentration of NaOH is 15g/L, and the volume fraction of monocrystalline silicon texturing additive is 0.63%. After the reaction, the silicon wafer is immersed in pure water at 55° C. for rinsing for 100 seconds.

Step 3, acid velvet:

Step 301, immerse the silicon wafer obtained in step 2 in a mixed solution C containing HF, HNO ₃ , and AgNO ₃ at 25°C for 90 seconds. In the mixed solution C, the volume fraction of HF is 27%, and the volume fraction of HNO ₃ is 15%, the mass concentration of AgNO ₃ is 0.06g/L, after the reaction, the silicon wafer is immersed in pure water and rinsed at room temperature for 30S.

Step 302, immersing the silicon wafer obtained in step 301 in a solution D containing _HNO3 at 45°C for cleaning to remove metal Ag particles in nanometer pores on the surface of the silicon wafer. In solution D, the volume fraction of _HNO3 is 43% , where three-level cleaning tanks are set to clean in sequence, each level of cleaning tank is initially filled with solution D, and the cleaning time of each level of cleaning tank is 35S, and the cleaning solution in the next level of cleaning tank can be returned to the previous level In the first-level cleaning tank, after being cleaned by the third-level cleaning tank, the silicon wafer is immersed in pure water and rinsed at room temperature for 40S.

Step 303, immerse the silicon wafer obtained in step 302 in the mixed solution E containing HF and _HNO3 at 30°C for 50 seconds to modify the nano-micropores on the surface of the pyramid. In the mixed solution E, the volume fraction of HF is 19 %, the volume fraction of HNO ₃ was 13%. After the reaction, the silicon wafer was immersed in pure water and rinsed at room temperature for 70S.

Step 4, alkali cleaning: immerse the silicon wafer obtained in step 303 in solution F containing KOH at 25°C and wash for 35 seconds. In solution F, the volume fraction of KOH is 2.5%. After cleaning, immerse the silicon wafer in pure water at room temperature Rinse for 50 seconds.

Step 5, pickling: immerse the silicon wafer obtained in step 4 in the mixed solution G containing HCl and HF and wash it at room temperature for 45 seconds. In the mixed solution G, the volume fraction of HCl is 17%, and the volume fraction of HF is 10%. After cleaning, immerse the wafer in pure water and rinse it for 70S at room temperature.

Step 6, slow pulling: immerse the silicon wafer obtained in step 5 in pure water at 70°C for 45 seconds to perform slow pulling.

The HF in step 301, step 303, and step 5 is the HF solution that mass concentration is 49%, and the HNO in step 301, step 302, and step 303 is the HNO that mass concentration is 68 _% Solution, in step ₅ HCl is a HCl solution with a mass concentration of 38%, and KOH in step 4 is a KOH solution with a mass concentration of 48%.

The equipment for realizing the high-efficiency single crystal texturing process of this embodiment is the same as that of Embodiment 1.

Example 4

A high-efficiency single crystal texturing process, comprising the following steps:

Step 1, remove the damaged layer: immerse the silicon wafer in the mixed solution A containing NaOH and H ₂ O ₂ at 63°C for 120 seconds to remove the stain and damaged layer on the surface of the silicon wafer. In the mixed solution A, the mass concentration of NaOH is 2.1g/L, the volume fraction of H ₂ O ₂ is 4.5%. After the reaction, immerse the silicon wafer in pure water at 63°C and rinse it for 110S.

Step 2, alkali texturing: immerse the silicon wafer obtained in step 1 in the mixed solution B containing NaOH and monocrystalline silicon texturing additive (Sanfeng MQT-330B6) at 80°C for 650 seconds to form a textured surface, In B, the mass concentration of NaOH is 15.6g/L, and the volume fraction of monocrystalline silicon texturing additive is 0.72%. After the reaction, the silicon wafer is immersed in pure water at 62°C and rinsed for 100S.

Step 3, acid velvet:

Step 301, immerse the silicon wafer obtained in step 2 in a mixed liquid C containing HF, HNO ₃ , and AgNO ₃ at 28°C for 80 seconds. In the mixed liquid C, the volume fraction of HF is 23%, and the volume fraction of HNO ₃ is 14%, the mass concentration of AgNO ₃ is 0.05g/L, after the reaction, the silicon wafer is immersed in pure water and rinsed at room temperature for 50S.

Step 302, immerse the silicon wafer obtained in step 301 in a solution D containing _HNO3 at 48°C for cleaning, and remove the metal Ag particles in the nanometer pores on the surface of the silicon wafer. In solution D, the volume fraction of _HNO3 is 38% , where three-level cleaning tanks are set to clean in sequence, each level of cleaning tank is initially filled with solution D, and the cleaning time of each level of cleaning tank is 45S, and the cleaning solution in the next level of cleaning tank can be returned to the previous level In the first-level cleaning tank, after being cleaned by the third-level cleaning tank, the silicon wafer is immersed in pure water and rinsed at room temperature for 45S.

Step 303, immerse the silicon wafer obtained in step 302 in the mixed solution E containing HF and _HNO3 at 25°C and react for 70 seconds to modify the nano-micropores on the surface of the pyramid. In the mixed solution E, the volume fraction of HF is 22 %, the volume fraction of HNO ₃ was 13%. After the reaction, the silicon wafer was immersed in pure water and rinsed at room temperature for 50S.

Step 4, alkali cleaning: immerse the silicon wafer obtained in step 303 in solution F containing KOH at 26°C and wash it for 45 seconds. In solution F, the volume fraction of KOH is 2.7%. After cleaning, immerse the silicon wafer in pure water at room temperature Rinse for 40 seconds.

Step 5, pickling: immerse the silicon wafer obtained in step 4 in the mixed solution G containing HCl and HF and wash it at room temperature for 40 seconds. In the mixed solution G, the volume fraction of HCl is 20%, and the volume fraction of HF is 12%. After cleaning, immerse the wafer in pure water and rinse it for 40S at room temperature.

Step 6, slow pulling: immerse the silicon wafer obtained in step 5 in pure water at 65°C for 45 seconds to perform slow pulling.

The HF in step 301, step 303, and step 5 is the HF solution that mass concentration is 49%, and the HNO in step 301, step 302, and step 303 is the HNO that mass concentration is 68 _% Solution, in step ₅ HCl is a HCl solution with a mass concentration of 38%, and KOH in step 4 is a KOH solution with a mass concentration of 48%.

The equipment for realizing the high-efficiency single crystal texturing process of this embodiment is the same as that of Embodiment 1.

comparative example

A single crystal texturing process using the existing alkali texturing technology, comprising the following steps:

Step 1, remove the damaged layer: immerse the silicon wafer in a mixed solution containing NaOH and H ₂ O ₂ at 65°C for 100 seconds to remove the stain and damaged layer on the surface of the silicon wafer. In the mixed solution, the mass concentration of NaOH is 3g /L, the volume fraction of H ₂ O ₂ is 5%. After the reaction, immerse the silicon wafer in pure water at 65°C for 80 seconds, and then immerse it in pure water at 65°C for 30 seconds.

Step 2, alkali texturing: immerse the silicon wafer obtained in step 1 in a mixed solution containing NaOH and monocrystalline silicon texturing additives at 80°C for 700 seconds to form a textured surface. In the mixed solution, the mass concentration of NaOH The volume fraction of monocrystalline silicon texturing additive is 0.7%. After the reaction, the silicon wafer is immersed in pure water at 60°C for rinsing for 100S.

Step 3, alkali cleaning: immerse the silicon wafer obtained in step ₂ in a mixed solution containing NaOH and H ₂ O ₂ at 65°C for 100 seconds. In the mixed solution, the mass concentration of _NaOH is 3g/L, and The volume fraction is 5%. After cleaning, immerse the silicon wafer in pure water and rinse it for 40S at room temperature.

Step 4, pickling: immerse the silicon wafer obtained in step 3 in a mixed solution containing HCl and HF and clean it for 40 seconds at room temperature. In the mixed solution, the volume fraction of HCl is 20%, and the volume fraction of HF is 25%. After cleaning, immerse the wafer in pure water and rinse it for 40 seconds at room temperature.

Step 5, slow pulling: immerse the silicon wafer obtained in step 5 in pure water at 65°C for 40 seconds to perform slow pulling.

The HF in step 4 is an HF solution with a mass concentration of 49%, and the HCl is an HCl solution with a mass concentration of 38%.

The electrical properties of the nano-textured battery sheet prepared in each embodiment were compared with the nano-micro-textured battery sheet prepared in the comparative examples, and the results are as follows:

Experiment category Voc Isc Rs. Rsh FF Eta Irev2 comparative example 0.67 9.693 0.0016 716 80.56 21.31% 0.044 Example 1 0.67 9.798 0.0014 869.5 81.33 21.85% 0.047 Example 2 0.67 9.796 0.0015 1737 80.84 21.84% 0.105 Example 3 0.67 9.780 0.0013 838 80.62 21.81% 0.105 Example 4 0.67 9.807 0.0015 2027 80.54 21.79% 0.074

It can be seen that through the high-efficiency single crystal texturing process of the present invention, the efficiency of the battery sheet can be increased by about 0.45%.

Claims (10)

1. A high-efficiency single crystal texturing process is characterized in that comprising the following steps: Step 1, remove the damaged layer: immerse the silicon wafer in the mixed solution A containing NaOH and H ₂ O ₂ to react, and then rinse with pure water. In the mixed solution A, the mass concentration of NaOH is 2g/L-2.5g/L , the volume fraction of H ₂ O ₂ is 4% to 5%, the reaction temperature is 60°C to 70°C, and the reaction time is 100S to 170S; Step 2, alkali texturing: the silicon wafer obtained in step 1 is immersed in the mixed solution B containing NaOH and monocrystalline silicon texturing additives to react, and then rinsed with pure water. In the mixed solution B, the mass concentration of NaOH is 15g/ L～17g/L, the volume fraction of monocrystalline silicon texturing additive is 0.6%～0.8%, the reaction temperature is 75℃～85℃, and the reaction time is 600S～800S; Step 3, acid velvet: Step 301, immerse the silicon wafer obtained in step 2 in a mixed solution C containing HF, HNO ₃ , and AgNO ₃ for reaction, and then rinse with pure water. In the mixed solution C, the volume fraction of HF is 20% to 30%, and the HNO The volume fraction of ₃ is 12%~16%, the mass concentration of AgNO ₃ is 0.04g/L~0.06g/L, the reaction temperature is 25℃~29℃, and the reaction time is 60S~100S; Step 302, immerse the silicon wafer obtained in step 301 in solution D containing HNO ₃ for cleaning, and then rinse with pure water. In solution D, the volume fraction of HNO ₃ is 30% to 60%, and the cleaning temperature is 40° C. to 50° C. ℃, cleaning time is 90S～150S; Step 303, immersing the silicon wafer obtained in step 302 in the mixed solution E containing HF and _HNO3 for reaction, and then rinsing with pure water. In the mixed solution E, the volume fraction of HF is 15% to 25%, and the volume fraction of _HNO3 The fraction is 12%~15%, the reaction temperature is 25℃~32℃, and the reaction time is 50S~80S; Step 4, alkali cleaning: immerse the silicon wafer obtained in step 303 in solution F containing KOH for cleaning, and then rinse with pure water. In solution F, the volume fraction of KOH is 2% to 3%, and the cleaning temperature is 25°C to 30℃, cleaning time is 30S～50S; Step 5, pickling: immerse the silicon wafer obtained in Step 4 in the mixed solution G containing HCl and HF for cleaning, and then rinse with pure water. In the mixed solution G, the volume fraction of HCl is 15% to 25%, and the volume fraction of HF is The volume fraction is 8%~15%, the cleaning temperature is room temperature, and the cleaning time is 30S~50S; Step 6, slow pulling: immerse the silicon wafer obtained in step 5 in pure water for slow pulling. 2. A kind of high-efficiency single crystal texturing process according to claim 1, characterized in that: the HF described in step 301, step 303, and step 5 are all HF solutions with a mass concentration of 49%, and step 301, step 302, the _HNO3 described in step 303 is the _HNO3 solution with a mass concentration of 68%, the HCl described in the step 5 is the HCl solution with a mass concentration of 38%, and the KOH described in the step 4 is a mass concentration of 48% KOH solution. 3. A high-efficiency single crystal texturing process according to claim 1, characterized in that: the pure water rinsing in step 1 is rinsing with pure water at 60°C to 70°C for 80S to 120S, and the rinsing in step 2 is The pure water rinsing described above is rinsing with pure water at 55°C-65°C for 100S-150S, the pure water rinsing described in step 301 is 30S-80S at room temperature, and the pure water rinse described in step rinsing with pure water at room temperature for 30S-50S, the rinsing with pure water in step 303 is rinsing with pure water for 30S-80S at room temperature, the rinsing in step 4 is rinsing with pure water at room temperature 30S-80S, the pure water rinsing in step 5 is rinsing with pure water at room temperature for 30S-80S. 4. A high-efficiency single crystal texturing process according to claim 1, characterized in that: the pure water in step 6 is 60°C-70°C, and the slow pulling time is 30S-50S. 5. A high-efficiency single crystal texturing process according to claim 1, characterized in that: the cleaning described in step 302 is at least two stages of cleaning tanks for sequential cleaning, each level of cleaning tank is solution D, the next The cleaning liquid in the first-level cleaning tank is returned to the upper-level cleaning tank. 6. A device for realizing the high-efficiency single crystal texturing process as claimed in claim 1, characterized in that: comprising a feeding device (1), an ultrasonic cleaning tank (2), a water tank A ( 3), single crystal alkali velvet tank (4), water tank B (5), acid velvet tank (6), water tank C (7), pickling silver removal tank (8), water tank D (9), pickling Modification tank (10), water tank E (11), alkali washing tank (12), water tank F (13), pickling tank (14), water tank G (15), slow lifting tank (16), feeding device ( 17), the ultrasonic cleaning tank (2) provides a mixed solution A containing NaOH and H ₂ O ₂ , and the single crystal alkali texturing tank (4) provides a mixed solution B containing NaOH and monocrystalline silicon texturing additives, The acid texturing tank (6) provides a mixed solution C containing HF, HNO ₃ , AgNO ₃ , the pickling silver removal tank (8) provides a solution D containing HNO ₃ , and the pickling modification tank (10) A mixed solution E containing HF and _HNO3 is provided, the alkaline washing tank (12) provides a solution F containing KOH, and the pickling tank (14) provides a mixed solution G containing HCl and HF. 7. The apparatus according to claim 1, further comprising a robot gripper (18) for transferring silicon wafers. 8. The equipment according to claim 1, characterized in that: the ultrasonic cleaning tank (2), water tank A (3), single crystal alkali texturing tank (4), water tank B (5), acid texturing tank (6), the tank body of pickling silver removal tank (8), pickling modification tank (10), alkali washing tank (12), pickling tank (14), slow lifting tank (16) is equipped with heating device, a temperature detector, to control the temperature of the liquid in the tank; the ultrasonic cleaning tank (2), the single crystal alkali texturing tank (4), the acid texturing tank (6), the pickling silver removal tank (8), the acid In the tank bodies of washing and modifying tank (10), alkaline cleaning tank (12), and pickling tank (14), an exhaust device is provided above the liquid level; the ultrasonic cleaning tank (2), water tank A (3) Ultrasonic generators are installed on the tank body. 9. The equipment according to claim 1, characterized in that: said pickling silver removal tank (8) is provided with at least two independent ones, each tank body is provided with an overflow port, and the acid in the latter tank body The washed liquid enters the previous tank body through the overflow port on it, and the pickled liquid in the first tank body overflows out of the tank body through the overflow port on it. 10. The equipment according to claim 1, characterized in that: the acid cashmere tank (6) and the pickling finishing tank (10) are equipped with peripheral heat exchangers and ice water machines, and the liquid in the tanks Exchanging heat with the chiller through the heat exchanger.