铜沉淀对直拉硅单晶中洁净区形成的影响

Effect of copper precipitation on the formation of denuded zone in Czchralski silicon

研究普通热处理和快速热处理工艺下直拉单晶硅中过渡族金属铜杂质对洁净区生成的影响.通过腐蚀和光学显微镜研究发现,常规高一低.高三步洁净区生成热处理样品中,第一步高温热处理前对样品铜沾污,样品中没有洁净区生成,高密度的铜沉淀布满了样品整个截面.而第二步、第三步热处理过程中引入铜杂质不影响洁净区的生成.研究表明,高温热处理过程中生成的铜沉淀不能溶解是导致洁净区不能形成的最主要原因.另外,由于不同温度下热处理,导致引入铜杂质的平衡浓度不同,会在一定程度上影响洁净区的厚度.对于快速热处理样品,可以得到相似的结果.

The influence of copper precipitation on the formation of denuded zone（DZ） in Czochralski silicon has been systematically investigated by means of optical microscopy.It was found that,for conventional furnace high-low-high annealing,the copper precipitates colonies generated along the whole crosssection in the specimens contaminated by copper impurity at the first step of the heat treatment, thus no DZ generated.While in other specimens,DZ formed.Additionally,it was found that the contamination temperature can influence significantly the thermodynamics and kinetic process of the formation of copper precipitates.The phenomena also occurred in the specimens underwent rapid thermal-low-high annealing.On the basis of the step by step investigation,it was revealed that the copper precipitates temperature and point defects type can influence the formation of DZ to a great extent.