石英微晶天平技术在原子层沉积碳化镍薄膜过程中的应用研究

Growth Mechanism of Nickel Carbide Thin Film by Atomic Layer Deposition: A Quartz Crystal Microbalance Study

采用等离子体增强原子层沉积技术分别以Ni(amd)2、Ni(dad)2为镍、碳前驱体,氢等离子体为还原剂成功沉积了碳化镍薄膜。两个沉积过程中,碳化镍薄膜厚度都随着反应循环次数的增加而线性增加。利用石英微晶天平技术对碳化镍薄膜的沉积过程进行了原位在线测量。初步提出碳化镍薄膜的沉积机理,其中由等离子体作用产生的氢原子对沉积过程有重要作用。一方面,在等离子体中原子氢与Ni(amd)2或Ni(dad)2发生化学反应,生成Ni、挥发性的N-叔丁基乙酰胺盐和碳氢化合物,这些镍在镍表面上有吸附和分解的趋势。此外,原子氢对吸附的碳氢化合物脱氢生成碳化镍和大量碳物种具有促进作用。另一方面,预计它还会刻蚀碳化镍表面的无定形碳和石墨,或者将碳化镍分解成具有催化活性的金属镍。

The nickel carbide thin films were grown at 95~C by H2-plasma enhanced atomic layer deposition （PEALD） with Ni （amd）2 or Ni （dad）2as Ni and C precursors. The influence of the atomic hydrogen on the growth was investigated by in-situ monitoring with quartz crystal microbalance （QCM）. The preliminary results show that the atomic hydrogen had a major impact. To be specific, on the one hand, dehydrogenation of the adsorbed hydrocarbons and formation of nickel carbide and amorphous carbon were enhanced by the reaction of atomic hydrogen with ehemisorbed Ni （amd） 2 and Ni （dad） 2 precursors, because, accompanied by Ni-releasing, the volatile N-tertbutylacetamidinate and CxHy,formed in the reaction,could be easily adsorbed and decomposed on Ni-surfaces. On the other hand, atomic hydrogen possibly etched the amorphous carbon and graphite adsorbed on nickel carbide surfaces or decomposed the nickel carbide into catalytically active Ni.