【摘要】 本文报道对直拉硅单晶碳沾污机理的研究.用气相色谱法分析了石英与石墨反应生成物CO的蒸气压P_co以及拉晶条件下石英坩埚和石墨托之间反应的P_co.在1512-1600K温度下测得不同载气Ar流速卞的P_co,然后外推至零流速下的P_co^o数值,由此求得SiO₂-C反应产生的co平衡蒸气压值P_co^o. 在直拉硅单晶工艺过程中碳沾污的主要来源是石英坩埚与石墨托之间反应产生的CO.将上面结果与热力学数据比较,可以推出:SiO₂-C系在上面温度范围内的主要反应是:C+SiO₂→SiO+CO. 用钼片隔开石墨托与石英坩埚后,在拉晶过程中CO量减少,单晶头部<50％处碳含量在红外测量灵敏度以下.此外还研究了晶体中碳含量与层错密度的关系.更多还原

【Abstract】 Transportation method is used in combination with gas chromatographic technique tomeasure CO pressure in equilibrium with SiO₂ and C under 1512-1660K.For the abovetemperature range, the values for equilibrium CO pressure can be determined.To comparewith the thermodynamical data,it is concluded that the reaction C+SiO₂（?）SiO+COis the predominated reaction between SiO₂ and C.The composition of the outgoing gas fromthe furnace during CZ process is measured.The predominant gaseous product is found tobe CO and SiO and the formation of CO only takes place when there is a quartz crucible inthe graphite pedestal.By using a Mo sheet to separate the graphite pedestal from the quartzcrucible,the carbon concentration in silicon crystals can be remarkably decreased.更多还原