对有限负压下熔体硅中磷的挥发去除进行研究。采用电子级硅配制SI-P合金,并采用gd-MS来检测实验前后硅中的磷含量。理论计算结果表明:在有限负压下,硅中的磷以P和P2的气体形式从熔体硅中挥发。实验结果显示:在温度1873k、真空度0.6-0.8PA、熔炼3600S的条件下,熔体硅中的磷从0.046%(460PPMW)下降到0.001%(10PPMW)。实验结果与理论结果一致表明:当熔体硅中磷的含量大且炉腔内气压相对较高时,磷的去除与气压高度相关;而当炉腔气压很低时,磷的去除基本与气压无关。原因是在相对高磷含量的熔体硅中,磷主要以P2气体的形式挥发;在磷含量较低时,磷主要以单原子气体P的形式挥发。Elimination of phosphorus vaporizing from silicon was investigated.Si-P alloy made from electronic grade silicon was used.All the samples were analyzed by GD-MS.Theory calculation determines that phosphorus evaporates from molten silicon as gas species P and P2 at a finite reduced pressure.The experimental results show that phosphorus mass fraction can be decreased from 0.046% (460ppmw) to around 0.001% (10ppmw) under the condition of temperature 1 873 K, chamber pressure 0.6-0.8 Pa, holding time 1 h.Both experimental data and calculation results agree that at high phosphorus concentration, phosphorus removal is quite dependent on high chamber pressure while it becomes independent on low chamber pressure.The reason is that phosphorus evaporates from molten silicon as gas species P2 at a relatively high phosphorus concentration, while gas species P will be dominated in its vapour at low phosphorus content.Project(2007J0012)supportedbytheNaturalScienceFoundationofFujianProvince;China;Project(2007HZ0005-2)supportedbytheKeyTechnologicalProgramofFujianProvince;China;Project(BASIC-10341702)supportedbyNorwegianResearchCounci
