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arXiv 1508.04059cond-mat.mtrl-sci
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薄膜内应力与沉积通量关系的热力学

Thermodynamics of Deposition Flux dependent Intrinsic Film Stress

Amirmehdi Saedi, Marcel J. Rost

摘要:

气相沉积在多晶薄膜上会导致压应力的交错水平,甚至超过薄膜的屈服强度。不幸的是,这种应力的很大一部分具有可逆性:当沉积停止时它消失,并在恢复时重新出现。虽然已经提出了许多机制来解释这些影响,但这种现象的起源仍然不清楚。在我们看来,原子在晶界的结合是最可能的机制,但它所需的驱动力尚未得到解决。因此,而不是寻找一个特定的(原子)纳入过程中,我们分析,在这里,整个膜系统仅使用热力学参数。我们发现,在实验中观察到的巨大的应力水平,可以令人惊讶地解释在极稀的吸附原子气体的表面上单独的通量引起的熵效应。这种热力学评估不仅提供了必要的基础上的吸附原子掺入模型,它甚至表明,可以达到低沉积通量的测量应力值。最后,完全违反直觉,我们还表明,应力水平下降,如果吸附原子到达晶界的障碍(S)减少!

英文摘要:

Vapor deposition on polycrystalline films can lead to staggering levels of compressive stress, exceeding even the yield strength of the films. Mysteriously, a significant part of this stress has a reversible nature: it disappears when the deposition is stopped and re-emerges upon resumption. Although numerous mechanisms have been proposed to explain these effects, the origin of the phenomenon remains still unclear. The incorporation of atoms in the grain boundaries is, to our opinion, the most likely mechanism, but the required driving force for it has not yet been addressed. Therefore, instead of searching for a specific (atomic) incorporation process, we analyze, here, the entire film system using thermodynamic arguments only. We find that the tremendous stress levels observed in the experiments can be surprisingly explained by the flux induced entropic effects in the extremely dilute adatom gas on the surface alone. This thermodynamic evaluation delivers not only the necessary basis for the adatom incorporation models, it even shows that the measured stress values can be reached with low deposition fluxes. Finally, fully counterintuitive, we also show that the stress levels decrease, if the barrier(s) for adatoms to reach the grain boundaries are decreased!

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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