A Molecular Dynamics Simulation on the Agglomeration Behavior of Cu on TaN(111) Surface
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摘要: 原子层沉积(ALD) 是下一代超大规模集成电路的首选工艺, 但是Cu籽晶层在阻挡层上的团聚限制了ALD工艺在半导体工业中的应用.目前对Cu在阻挡层TaN表面的团聚机理和行为还缺乏足够的理论认识, 为此利用第一性原理密度泛函理论(DFT) 对不同覆盖度下Cu原子在TaN (111) 表面的吸附能和电荷转移进行了研究, 结果显示, Cu在TaN (111) 表面的吸附强度随着Cu覆盖度的增加而减弱.利用从头算分子动力学模拟了500K温度下Cu单分子层在TaN (111) 表面的吸附动力学行为, 结果表明, 在这一典型的ALD温度下, Cu层在TaN (111) 表面发生团聚, 与实验中的观察结果相符.Abstract: Cu seed layer agglomeration on barriers is a bottleneck in semiconductor industry for the application of atomic layer deposition (ALD) which is the preferred technology for the next-generation ultra large-scale integrated circuit (ULSC).However, the theoretical understanding of the underlying mechanisms of Cu aggregation is still not clearly known.We made a first-principles study of copper aggregation on the TaN (111) surface, using density functional theory.The adsorption energies and charge transfers were evaluated to address the interactions between Cu and the substrate.Ab initio molecular dynamics simulations were performed to examine the dynamic behavior of a copper monolayer originally commensurate with the TaN substrate at the typical atomic layer deposition (ALD) operating temperature (500 K).The results revealed that the copper film underwent substantial agglomeration on the TaN (111) surface at this ALD operating temperature, which was consistent with experimental observations.
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Key words:
- agglomeration /
- TaN /
- DFT /
- molecular dynamics /
- semiconductor materials.
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图 1 TaN (111) 表面的侧视图(a) 和俯视图(b)
Fig. 1. Side view (a) and top view (b) of TaN (111) surface
图 2 分子动力学过程中的几个时间点的结构(a) 和TaN表面Cu团聚形成的孤岛的SEM照片(b) (Zhao et al., 2007)
Fig. 2. Snapshot of the MD trajectory (a) and SEM image of Cu islands on TaN surface (b)
图 3 纯TaN表面(a)、TaN表面吸附Cu单层(b) 和TaN表面吸附团聚之后的Cu (c) 的电子态密度
Fig. 3. Electron density of states of TaN surface (a), Cu monolayer adsorbed on TaN surface (b) and Cu agglomerated on TaN surface (c)
图 4 Cu-Cu、Cu-N和Ta-N原子间距离的距离分布函数
Fig. 4. Distance distribution function of Cu-Cu, Cu-N and Ta-N
表 1 TaN (111) 表面吸附不同覆盖度的Cu原子的吸附能和电子转移
Table 1. Adsorption energy and electron transfer of copper on TaN (111) surface at different coverage
表 2 TaN (111) 和WN (001) 表面作为不同吸附基底的比较
Table 2. Comparison between TaN (111) and WN (001) substrate
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