系统研究了点缺陷对晶体硅中氧沉淀生成的影响,及点缺陷和氧沉淀对重掺硼直拉硅单晶P/P+外延片中铜沉淀的影响.样品先在不同的气氛下进行1250℃/60S快速热处理,随后在750℃/8h+1050℃/16h常规热处理过程中引入铜沾污.通过腐蚀结合光学显微镜研究发现,以O2作为保护气氛时,P+衬底中的沉淀密度较小,以Ar和N2作为保护气氛时,重掺硼p+衬底中生成了高密度的沉淀,且在上述所有样品的外延层中均无缺陷生成.研究认为,以O2作为保护气时引入的自间隙硅原子(SiI)可以抑制沉淀的形成,而以Ar和N2作为保护气氛时引入的空位则会促进沉淀的生成,这是导致此差异的主要原因.另外,研究还发现,p/p+外延结构能很好地吸除硅片中的铜杂质,从而保持了外延层的洁净.
The effect of point defects on copper precipitation in heavily boron-doped Czochralski silicon epitaxial wafer is systematically investigated by optical microscopy. The samples first experience the rapid thermal processing (RTP) in different atmospheres, and then are Cu-contaminated at different temperatures. It is found that RTP in O2 ambient leads to a low density of copper precipitation in the p+ substrate, however, high density of copper precipitation is observed in the sample subjected to RTP in Ar or N2 ambient. Additionally, in all of the samples, no defects are found in the epitaxial layer. On the basis of the experiments, it can be concluded that interstitial silicon will prevent the process of copper precipitation while vacancy has an opposite effect. Furthermore, p/p+ epitaxial structure could absorb copper impurities, thereby keeping the epitaxial layer free of defect.