硅中金属杂质的原子半径失配较大,扩散系数也较掺杂元素高几个数量级,再加它们的溶解度随温度剧烈变化,这些促使它们在硅中极易发生聚集及形成沉积团,此类聚集及沉积团会使p-n结软化及器件制造失效。B.L.Graydon曾用中子活化分析了金属杂质在外延层表面富集,C.W.Pearce曾指出外延衬底金属沾污会引起外延 The mismatch in the atomic radius of the metallic impurity in silicon is larger, and the diffusion coefficient is several orders of magnitude higher than that of the doping element, and their solubility changes drastically with temperature, which causes them to easily aggregate and form deposition clusters in silicon Clustering and deposition of clusters will pn junction softening and device manufacturing failure. B.L.Graydon has used neutron activation analysis of the metal impurities in the epitaxial layer surface enrichment, C.W. Pearce pointed out that the epitaxial substrate metal contamination can cause the extension