Solar Grade-Silicon, Ingot, Wafer Technology and Market Trend

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Solar Grade-Silicon, Ingot, Wafer Technology and Market Trend (2008~2012) All Contents of this report remain the property of Displaybank 3SiCl4 + 2H2 + Si = 4SiHCl3 This process spills mixture of tetrachlorosilane and hydrogen to the metallurgical silicon within a fluidized reactor usually at 500°C and 35 bars and obtains trichlorosilane. Figure 2.10. Interior of Siemens Reactor The Siemens process has rather poor energy efficiency; it consumes a large amount of electricity to maintain extraction temperature at higher than 1,000℃ during the process and has a great loss in amount of heat while continuously cooling down interior walls with circulating coolants to prevent Si extractions. Usually, it loses more than 90% of energy input in exterior cooling walls. The Siemens methods consumes about 60~150kWh in manufacturing 1 kg of SoG-Si. Hence, it installs several bars within the Siemens reactor in order to enhance the low efficiency (refer to figure 2.11). SAMPLE Jan’09
Solar Grade-Silicon, Ingot, Wafer Technology and Market Trend (2008~2012) 2.4.2 Vapor to Liquid Deposition (VLD): Tokuyama VLD method produces trichlorosilane or monosilane gasses by reacting metallic silicon with either hydrochloric acid or hydrogen, and then produces liquid silicon directly from the gas. It is similar to the Siemens process in using trichlorosilane gasses, but it obtains liquid silicon as the gas undergoes a tubeshaped reactor with inductive heating to be restored. Figure 2.4.2 VLD Method Concept Source: Tokuyama Hence, VLD method has outstanding efficiency and productivity. It has extraction speed 10 times faster than the conventional Siemens process, but is difficult to delete impurities. The Siemens process starts with obtaining semiconductor silicon with ultra high purity and is applied to the solar gradesilicon production by lowering the quality and enhancing the productivity. On the other hand, VLD process is suitable for the solar grade-silicon production which requires relatively lower quality and high productivity. The VLD process is currently known to be developed by Tokuyama, but has difficulties in terms of yield. Its energy efficiency is more than 5 times higher than the Siemens process. All Contents of this report remain the property of Displaybank SAMPLE Jan’09
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Solar Grade-Silicon, Ingot, Wafer Technology and Market Trend

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