Method for preparing polysilicon
A technology of polysilicon and liquid silicon, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problems of low purification degree, short process flow, and cannot be reduced, and achieve good impurity removal effect, reduce process steps, and operate simplified effect
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Embodiment 1
[0022] Put 200Kg of raw silicon containing 10ppm boron and 10ppm phosphorus into a refining furnace, and conduct electric heating in an air atmosphere at 1 atmosphere until the silicon becomes molten. Keep the liquid silicon temperature at 1455°C, put 200kg of CaO containing 72Kg, 36Kg of Na 2 CO 3 and 92Kg of SiO 2 The basic slagging agent is put into liquid silicon in 40 times for refining. Each addition is 5Kg, with an interval of 10 minutes each time. After the refining is completed, filter out the slag in the liquid silicon, then transfer the liquid silicon to the casting container through the microporous filter of the casting container, and finally orient the liquid silicon at a cooling rate of 60°C / hour Cool to obtain a silicon ingot. After the cooled silicon ingot is pulverized and cleaned, the purity analysis is carried out. The analysis results show that the boron content is 0.35ppm; the phosphorus content is 0.6ppm, meeting the requirements of solar grade silico...
Embodiment 2
[0024] Put 100kg of boron-containing 100ppm and phosphorus-containing 30ppm raw silicon 100Kg into a refining furnace, and conduct electrical heating in an air atmosphere at 1 atmosphere until the silicon becomes molten. Keep the temperature of liquid silicon at 1455°C, put 125 kg of CaO containing 45Kg, 22.5Kg of Na 2 CO 3 and 57.5Kg of SiO 2 The basic slagging agent is put into liquid silicon 100 times for refining. The amount of adding each time is 1.25Kg, and each interval is 10 minutes. After the refining is completed, filter out the slag in the liquid silicon, then transfer the liquid silicon to the casting container through the microporous filter of the casting container, and finally orient the liquid silicon at a cooling rate of 60°C / hour Cool to obtain a silicon ingot. After the cooled silicon ingot is pulverized and cleaned, the purity analysis is carried out. The analysis results show that the boron content is 0.3ppm; the phosphorus content is 0.5ppm, which meet...
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