Silicon wafer texturing production line

Abstract

The application discloses a silicon wafer texturing production line, which comprises chain type oxidation furnaces, first chain type acid washing machines, first wafer inserting machines, oxidation tanks, first clean water tanks, texturing tanks, second clean water tanks, second wafer inserting machines, second chain type acid washing machines and chain type drying furnaces arranged in sequence according to working procedures. The chain type oxidation furnaces are arranged in front of the texturing tanks, the silicon wafers can be subjected to high-temperature oxidation treatment in the chain type oxidation furnaces before texturing, organic dirt on the surface of the silicon wafers can be decomposed, the organic dirt on the surface of the silicon wafers can be completely removed, and problems, such as white spots and bright spots, caused by the organic dirt remaining on the surface of the silicon wafers during texturing can be avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to a silicon wafer texturing production line. BACKGROUND

[0002] Photovoltaic power generation is the most important part of solar energy utilization, which is an environmentally friendly, inexhaustible renewable energy source, in line with the pursuit of high efficiency and low cost in the photovoltaic industry. For single crystal silicon cells, surface reflectivity is one of the important factors affecting the efficiency conversion of solar cells. In order to reduce the surface reflectivity, the texturing process plays an important role.

[0003] The purpose of texturing is to produce texture on the surface of the original silicon wafer to achieve light trapping effect, thereby improving the solar absorption rate and further improving the photoelectric conversion rate of the cell. The texturing process on the market is still the traditional wet process. After the texturing process is completed, there will be a high probability of white spots, bright spots and other problems on the silicon wafer, which seriously affects the straight-through rate of the production line and reduces the efficiency of the production line. SUMMARY

[0004] In order to solve the defects of the prior art, the present application provides a silicon wafer texturing production line, which comprises, in order of process sequence: a chain type oxidation furnace, a first chain type acid pickling machine, an oxidation tank, a first water tank and a texturing tank.

[0005] Preferably, it further comprises, in order of process sequence, a second water tank, a second chain type acid pickling machine and a chain type drying furnace located after the texturing tank.

[0006] Preferably, the first chain type acid pickling machine comprises, in order of process sequence, an acid pickling area and a rinsing area.

[0007] Preferably, the acid pickling area of the first chain type acid pickling machine is provided with a liquid roller and a spray head, and the rinsing area of the first chain type acid pickling machine is provided with a roller and a spray head.

[0008] Preferably, a first wafer inserting machine is further arranged between the first chain type acid pickling machine and the oxidation tank.

[0009] Preferably, the second chain type acid pickling machine comprises, in order of process sequence, an acid pickling area and a rinsing area.

[0010] Preferably, the acid pickling area of the second chain type acid pickling machine is provided with a liquid roller and a spray head, and the rinsing area of the second chain type acid pickling machine is provided with a roller and a spray head.

[0011] Preferably, a second wafer inserting machine is further arranged between the second water tank and the second chain type acid pickling machine.

[0012] Preferably, the chain type oxidation furnace is provided with a corundum shaft and a heating lamp tube.

[0013] The research shows that the reason why the white spot and bright spot problems occur in the texturing of the silicon wafer is that the organic dirt remains on the surface of the silicon wafer. The chain type oxidation furnace is arranged in front of the texturing tank, the silicon wafer is subjected to high temperature oxidation treatment in the chain type oxidation furnace before texturing, the organic dirt on the surface of the silicon wafer is decomposed, the organic dirt on the surface of the silicon wafer can be completely removed, and the white spot and bright spot problems caused by the organic dirt remaining on the surface of the silicon wafer can be avoided.

[0014] However, the inventors of the present application find that, in order to completely remove the organic dirt on the surface of the silicon wafer, the temperature of the chain type oxidation furnace is high (300-800 ℃), the processing time is long (180-250 s), and after the high temperature oxidation treatment is completed, a relatively thick SiO2 layer is formed on the surface of the silicon wafer, the thickness of the SiO2 layer is not less than 2 nm (the thickness of the SiO2 layer is 2-8 nm), and the relatively thick SiO2 layer will affect the texturing and is not conducive to the texturing. In order to prevent the relatively thick SiO2 layer from affecting the texturing, the first chain type acid pickling machine is arranged in front of the texturing tank, and the silicon wafer is subjected to acid pickling (hydrofluoric acid solution is used for acid pickling) in the first chain type acid pickling machine, so that the relatively thick SiO2 layer is completely removed.

[0015] However, the inventors of the present application find that, after the above-mentioned relatively thick SiO2 layer is removed, the surface of the silicon wafer is in a hydrophobic state, and the surface of the silicon wafer in the hydrophobic state will also affect the texturing and is not conducive to the texturing. In order to prevent the surface of the silicon wafer from being in the hydrophobic state and affecting the texturing, the oxidation tank is arranged in front of the texturing tank, and the silicon wafer is subjected to re-oxidation in the oxidation tank, so that the SiO2 layer is formed on the surface of the silicon wafer again. The thickness of the SiO2 layer formed again can be controlled by controlling the process parameters of the re-oxidation (the oxidation treatment liquid prepared by 2%-6% H2O2, 1%-3% inorganic alkali and the rest deionized water is used in the oxidation tank, the silicon wafer is subjected to oxidation treatment at 60-70 ℃ for 2-3 min), so that the thickness of the SiO2 layer formed again is not more than 0.6 nm (the thickness of the SiO2 layer formed again is controlled to be 0.2-0.6 nm). The ultra-thin SiO2 layer not only will not affect the texturing, but also will make the surface of the silicon wafer in a hydrophilic state, which is conducive to the texturing.

[0016] The root of the texturing is that the Si on the surface of the silicon wafer reacts with the texturing solution. If the thickness of the SiO2 on the surface of the silicon wafer is not less than 2 nm, the surface treatment of the silicon wafer during the texturing will not be enough, which will lead to incomplete reaction and too high reflectivity of the surface of the silicon wafer. When the thickness of the SiO2 is not more than 0.6 nm, the texturing can be completely performed in cooperation with the existing texturing process, and the texturing will not be affected.

[0017] In addition, the silicon wafer texturing production line of the present application is used to produce the texturing wafer, and many steps except the texturing step can be operated in a chain type, which is more efficient.

[0018] In conclusion, the present application can not only solve the problem of white spot and bright spot in the wafer texturing caused by the organic dirt remaining on the surface of the silicon wafer, but also improve the yield of the wafer texturing and reduce the defective rate of the wafer texturing, and has popularization value. DETAILED DESCRIPTION

[0019] The specific embodiments of the present application are further described below in conjunction with examples. The following examples are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0020] The present application provides a silicon wafer texturing production line, comprising, in order of process sequence: a chain type oxidation furnace, a first chain type acid washing machine, a first wafer inserting machine, an oxidation tank, a first clean water tank, a texturing tank, a second clean water tank, a second wafer inserting machine, a second chain type acid washing machine, and a chain type drying furnace.

[0021] The chain type oxidation furnace is internally provided with a corundum shaft and a heating lamp tube.

[0022] The first chain type acid washing machine comprises, in order of process sequence: an acid washing area and a rinsing area; the acid washing area of the first chain type acid washing machine is provided with liquid carrying rollers and nozzles, and the rinsing area of the first chain type acid washing machine is provided with rollers and nozzles.

[0023] The second chain type acid washing machine comprises, in order of process sequence: an acid washing area and a rinsing area; the acid washing area of the second chain type acid washing machine is provided with liquid carrying rollers and nozzles, and the rinsing area of the second chain type acid washing machine is provided with rollers and nozzles.

[0024] The present application further provides a production process of the above-mentioned silicon wafer texturing production line.

[0025] 1) A plurality of silicon wafers enter the chain type oxidation furnace for high-temperature oxidation treatment, the temperature of the high-temperature oxidation treatment is 300-800℃, and the time is 180-250s, so that the organic dirt on the surface of the silicon wafer is decomposed to remove the organic dirt on the surface of the silicon wafer, and a SiO2 layer is formed on the surface of the silicon wafer;

[0026] 2) The silicon wafer treated in step 1) enters the acid washing area of the first chain type acid washing machine for 2-6min normal-temperature acid washing to remove the SiO2 layer on the surface of the silicon wafer; the acid solution used for the acid washing is prepared by 5wt%-10wt% HF and the rest deionized water;

[0027] 3) The silicon wafer treated in step 2) enters the rinsing area of the first chain type acid washing machine for 3-9min normal-temperature rinsing to remove the residual acid solution on the surface of the silicon wafer;

[0028] 4) The silicon wafer after step 3) is inserted into a first wafer inserting machine and then enters an oxidation tank for re-oxidation for 2-3 min at 60-70℃, so that a SiO2 layer is formed on the surface of the silicon wafer again to make the surface of the silicon wafer hydrophilic, and the thickness of the SiO2 layer formed again is controlled to be 0.2-0.6 nm; the oxidation treatment solution in the oxidation tank is prepared from 2wt%-6wt% H2O2, 1wt%-3wt% inorganic base and the balance of deionized water; the inorganic base can be KOH or NaOH;

[0029] 5) The silicon wafer after step 4) enters a first clean water tank for normal-temperature rinsing for 3-5 min to remove the residual oxidation treatment solution on the surface of the silicon wafer;

[0030] 6) The silicon wafer after step 5) enters a texturing tank for texturing at 75-85℃ for 6-8 min to form a textured structure on the surface of the silicon wafer; the texturing solution in the texturing tank is prepared from 0.5wt%-1wt% texturing additive, 1wt%-3wt% inorganic base and the balance of deionized water; the inorganic base can be KOH or NaOH;

[0031] 7) The silicon wafer after step 6) enters a second clean water tank for normal-temperature rinsing for 3-5 min to remove the residual texturing solution on the surface of the silicon wafer;

[0032] 8) The silicon wafer after step 7) is placed into a second wafer inserting machine and then enters an acid washing area of a second chain-type acid washing machine for normal-temperature acid washing for 2-6 min to remove the oxide layer and metal ions on the surface of the silicon wafer; the acid solution used for acid washing is prepared from 5wt%-10wt% HF, 5wt%-10wt% HCL and the balance of deionized water;

[0033] 9) The silicon wafer after step 8) enters a rinsing area of the second chain-type acid washing machine for normal-temperature rinsing for 3-9 min to remove the residual second acid solution on the surface of the silicon wafer;

[0034] 10) The silicon wafer after step 9) enters a chain-type drying furnace and is dried at 80-90℃ for 10-30 min.

[0035] The specific implementation of the present application is as follows:

[0036] Example 1

[0037] 1) 1200 silicon wafers enter a chain-type oxidation furnace for high-temperature oxidation treatment at 700℃ for 180 s;

[0038] 2) The 1200 silicon wafers after step 1) enter an acid washing area of a first chain-type acid washing machine for normal-temperature acid washing for 5 min; the acid solution used for acid washing is prepared from 5wt% HF and 95wt% deionized water;

[0039] 3) 1200 wafers after step 2) are put into the rinsing area of the first chain type acid washing machine for 6 min normal temperature rinsing;

[0040] 4) 1200 wafers after step 3) are put into the oxidation tank for re-oxidation after being inserted by the first wafer inserting machine, the time is 2 min 10 s, the temperature is 60°C, and the oxidation treatment solution in the oxidation tank is prepared by 5wt% H2O2, 2wt% NaOH and 93wt% deionized water;

[0041] 5) 1200 wafers after step 4) are put into the first water tank for 3 min normal temperature rinsing;

[0042] 6) 1200 wafers after step 5) are put into the texturing tank for 6 min 30 s texturing at 78°C, and the texturing solution in the texturing tank is prepared by 1wt% texturing additive, 2wt% NaOH and 97wt% deionized water;

[0043] 7) 1200 wafers after step 6) are put into the second water tank for 3 min normal temperature rinsing;

[0044] 8) 1200 wafers after step 7) are put into the second chain type acid washing machine for 5 min normal temperature acid washing after being inserted by the second wafer inserting machine, and the acid solution used for acid washing is prepared by 5wt% HF, 5wt% HCL and 90wt% deionized water;

[0045] 9) 1200 wafers after step 8) are put into the rinsing area of the second chain type acid washing machine for 6 min normal temperature rinsing;

[0046] 10) 1200 wafers after step 9) are put into the chain type drying furnace for 15 min drying at 88°C.

[0047] Example 1 produces 1200 wafers, and the surface of each wafer is free of white spots and bright spots, and the defective rate is 0.005%.

[0048] Example 2

[0049] 1) 1200 wafers are put into the chain type oxidation furnace for high temperature oxidation treatment, the temperature is 500°C, and the time is 200 s;

[0050] 2) 1200 wafers after step 1) are put into the acid washing area of the first chain type acid washing machine for 3 min normal temperature acid washing, and the acid solution used for acid washing is prepared by 7wt% HF and 93wt% deionized water;

[0051] 3) 1200 wafers after step 2) are put into the rinsing area of the first chain type acid washing machine for 5 min normal temperature rinsing;

[0052] 4) 1200 wafers after step 3) are inserted into the first wafer inserting machine and then into the oxidation tank for re-oxidation for 2 min 10 s at 60°C, and the oxidation solution in the oxidation tank is prepared from 5wt% H2O2, 2wt% NaOH and 93wt% deionized water;

[0053] 5) 1200 wafers after step 4) are put into the first clean water tank for normal temperature rinsing for 3 min;

[0054] 6) 1200 wafers after step 5) are put into the texturing tank for texturing at 78°C for 6 min 30 s, and the texturing solution in the texturing tank is prepared from 1wt% texturing additive, 2wt% NaOH and 97wt% deionized water;

[0055] 7) 1200 wafers after step 6) are put into the second clean water tank for normal temperature rinsing for 3 min;

[0056] 8) 1200 wafers after step 7) are put into the second wafer inserting machine and then into the acid washing area of the second chain type acid washing machine for 5 min normal temperature acid washing, and the acid solution for acid washing is prepared from 5wt% HF, 5wt% HCL and 90wt% deionized water;

[0057] 9) 1200 wafers after step 8) are put into the rinsing area of the second chain type acid washing machine for 6 min normal temperature rinsing;

[0058] 10) 1200 wafers after step 9) are put into the chain type drying furnace for drying at 88°C for 15 min.

[0059] Example 2 produces 1200 texturing wafers, and the surface of each wafer is free of white spots and bright spots, and the defective rate is 0.01%.

[0060] Example 3

[0061] 1) 1200 wafers are put into the chain type oxidation furnace for high temperature oxidation treatment at 300°C for 240 s;

[0062] 2) 1200 wafers after step 1) are put into the acid washing area of the first chain type acid washing machine for 2 min 30 s normal temperature acid washing, and the acid solution for acid washing is prepared from 9wt% HF and 91wt% deionized water;

[0063] 3) 1200 wafers after step 2) are put into the rinsing area of the first chain type acid washing machine for 3 min normal temperature rinsing;

[0064] 4) 1200 pieces of silicon wafers after step 3) are inserted into the first wafer inserting machine and then enter the oxidation tank for re-oxidation, the time is 2 min and the temperature is 60℃, the oxidation treatment solution in the oxidation tank is prepared by 6wt% H2O2, 3wt% NaOH and 91wt% deionized water;

[0065] 5) 1200 pieces of silicon wafers after step 4) enter the first clean water tank for normal temperature rinsing for 3 min;

[0066] 6) 1200 pieces of silicon wafers after step 5) enter the etching tank for etching at 78℃ for 6min40s, the etching solution in the etching tank is prepared by 0.8wt% etching additive, 2wt% NaOH and 97.2wt% deionized water;

[0067] 7) 1200 pieces of silicon wafers after step 6) enter the second clean water tank for normal temperature rinsing for 3 min;

[0068] 8) 1200 pieces of silicon wafers after step 7) are placed into the second wafer inserting machine and then enter the acid washing area of the second chain type acid washing machine for 5min normal temperature acid washing, the acid solution used for acid washing is prepared by 5wt% HF, 5wt% HCL and 90wt% deionized water;

[0069] 9) 1200 pieces of silicon wafers after step 8) enter the rinsing area of the second chain type acid washing machine for 6min normal temperature rinsing;

[0070] 10) 1200 pieces of silicon wafers after step 9) enter the chain type drying furnace and are dried at 88℃ for 15min.

[0071] Example 3 produces 1200 pieces of etched wafers, the surfaces of which are free of white spots and bright spots, and the defective rate is 0.

[0072] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A production process of a silicon wafer texturing production line, characterized in that: the silicon wafer texturing production line comprises, in order, a chain type oxidation furnace, a first chain type acid washing machine, a first wafer inserting machine, an oxidation tank, a first clean water tank, a texturing tank, a second clean water tank, a second wafer inserting machine, a second chain type acid washing machine, and a chain type drying furnace; the chain type oxidation furnace is internally provided with a corundum shaft and heating lamp tubes; the first chain type acid washing machine comprises, in order, an acid washing zone and a rinsing zone; the acid washing zone of the first chain type acid washing machine is provided with liquid carrying rollers and nozzles, and the rinsing zone of the first chain type acid washing machine is provided with rollers and nozzles; the second chain type acid washing machine comprises, in order, an acid washing zone and a rinsing zone; the acid washing zone of the second chain type acid washing machine is provided with liquid carrying rollers and nozzles, and the rinsing zone of the second chain type acid washing machine is provided with rollers and nozzles; the production process comprises: 1) a plurality of silicon wafers enter the chain type oxidation furnace for high-temperature oxidation treatment at a temperature of 300-800°C for 180-250s, so that organic dirt on the surface of the silicon wafers is decomposed to remove the organic dirt on the surface of the silicon wafers, and a SiO2 layer is formed on the surface of the silicon wafers; 2) the silicon wafers treated in step 1) enter the acid washing zone of the first chain type acid washing machine for normal-temperature acid washing for 2-6min to remove the SiO2 layer on the surface of the silicon wafers; the acid solution used for acid washing is prepared from 5wt%-10wt% HF and a residual amount of deionized water; 3) the silicon wafers treated in step 2) enter the rinsing zone of the first chain type acid washing machine for normal-temperature rinsing for 3-9min to remove residual acid solution on the surface of the silicon wafers; 4) the silicon wafers treated in step 3) are inserted by the first wafer inserting machine and then enter the oxidation tank for re-oxidation for 2-3min at a temperature of 60-70°C, so that a SiO2 layer is formed again on the surface of the silicon wafers to make the surface of the silicon wafers hydrophilic, and the thickness of the SiO2 layer formed again is controlled to be 0.2-0.6nm, which does not affect texturing and is beneficial to texturing; the oxidation treatment solution in the oxidation tank is prepared from 2wt%-6wt% H2O2, 1wt%-3wt% inorganic alkali, and a residual amount of deionized water; the inorganic alkali is selected from KOH and NaOH; 5) the silicon wafers treated in step 4) enter the first clean water tank for normal-temperature rinsing for 3-5min to remove residual oxidation treatment solution on the surface of the silicon wafers; 6) the silicon wafers treated in step 5) enter the texturing tank for texturing at 75-85°C for 6-8min to form a textured structure on the surface of the silicon wafers; the texturing solution in the texturing tank is prepared from 0.5wt%-1wt% texturing additive, 1wt%-3wt% inorganic alkali, and a residual amount of deionized water; the inorganic alkali is selected from KOH and NaOH; 7) the silicon wafers treated in step 6) enter the second clean water tank for normal-temperature rinsing for 3-5min to remove residual texturing solution on the surface of the silicon wafers. 8) The silicon wafer treated in step 7) is put into the second chain-type pick-up machine and then into the acid washing area of the second chain-type acid washing machine for 2-6 minutes of normal temperature acid washing to remove the oxide layer and metal ions on the surface of the silicon wafer; the acid solution used for acid washing is prepared from 5wt%-10wt% HF, 5wt%-10wt% HCL and the rest deionized water; 9) The silicon wafer treated in step 8) is put into the rinsing area of the second chain-type acid washing machine for 3-9 minutes of normal temperature rinsing to remove the residual second acid solution on the surface of the silicon wafer; 10) The silicon wafer treated in step 9) is put into the chain-type drying furnace for 10-30 minutes of drying at 80-90°C.