多晶硅生产中硅芯色泽异常的机理研究

STUDY ON MECHANISM OF COLOR ABONORMAL SILICON CORE IN POLYSILICON PRODUCTION

采用HF溶液对硅芯进行腐蚀实验,利用电子探针(EPMA)和X射线光电子能谱(XPS)方法分析成品硅芯和色泽异常硅芯表面化学成分,研究硅芯色泽异常的主要机理。研究结果表明,成品硅芯表面仅含Si元素,无其他杂质元素。通过酸腐蚀EPMA和XPS分析发现,色泽异常硅芯的化学成分与化学性能无明显对应关系,不同的形成机理导致硅芯的色泽不同。氢气中的甲烷在高温下形成炭黑附着在硅芯表面上。黑黄色样品的表面层成分复杂,从里到外依次为硅氧化合物、无定形硅和炭黑组成的薄膜。其中无定形硅薄膜和硅氧化合物薄膜形成的机理为还原炉内SiHCl3/SiH2Cl2热分解形成的微硅粉和残留的微量氧/水分导致。

The chemical composition of the surface of the end-product silicon core and the abnormal silicon core was analyzed by HF solution,EPMA and XPS. The formation mechanism of the most unusual silicon core was studied. The results showed that:1)the surface of end-product silicon core only Si element,no other impurity elements. 2)Through acid corrosion,EPMA and XPS analysis found that the chemical composition of the abnormal silicon core and chemical properties of no significant relationship,and different formation mechanisms lead to different color of silicon cores. The methane in the hydrogen decomposes at high temperatures to carbon black that adheres to the surface of the silicon core.3)The surface layer composition of black and yellow samples is complex,which from the inside to the outside in order of silicon oxide,amorphous silicon and carbon black film. The formation mechanism of the amorphous silicon thin film and the silicon oxide thin film is caused by the micro-silica powder formed by the thermal decomposition of SiHCl3/SiH2 Cl2 and the trace oxygen/water remaining in the reduction furnace.