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以工业硅为原料,利用介质熔炼、定向凝固和电子束熔炼三种熔体处理技术对工业硅中的B、P和金属杂质进行了去除,制备出了99.9999%级多晶硅材料,其中,杂质B和P的含量分别低于0.20 ppmw(parts per million(weight),百万分之一质量),金属杂质总含量(TM)低于0.23 ppmw。研究发现,介质熔炼去除杂质B的过程中,熔体中发生氧化还原反应可以有效去除大部分的杂质Al和Ca;电子束熔炼过程中,利用饱和蒸气压原理可以有效去除挥发性杂质P、Al、Ca,同时降束诱导多晶硅定向凝固,可将其他金属杂质进一步去除。本研究通过各技术间的耦合除杂,减少了冶金法提纯多晶硅的工序,为连续化、规模化生产提供了技术支撑。
Using industrial silicon as raw material, B, P and metal impurities in industrial silicon were removed by using three kinds of melt processing technologies of medium melting, directional solidification and electron beam melting to prepare a 99.9999% grade polysilicon material, in which impurity B And P are less than 0.20 ppmw (parts per million, respectively) and the total content of metal impurities (TM) is less than 0.23 ppmw. It is found that the redox reaction in the melt can remove most of the impurities Al and Ca effectively during the process of removing impurities B by smelting medium. During the electron beam melting process, the saturated vapor pressure principle can effectively remove the volatile impurities such as P and Al , Ca, while reducing beam induced polycrystalline silicon directional solidification, other metal impurities can be further removed. In this study, through the coupling and impurity removal among various technologies, the process of purifying polycrystalline silicon by metallurgy was reduced, which provided technical support for continuous and large-scale production.