Re-examination of the Aqueous Stability of Atomic Layer Deposited (ALD) Amorphous Alumina (Al 2 O 3 ) Thin Films and the Use of a Postdeposition Air Plasma Anneal to Enhance Stability
Re-examination of the Aqueous Stability of Atomic Layer Deposited (ALD) Amorphous Alumina (Al 2 O 3 ) Thin Films and the Use of a Postdeposition Air Plasma Anneal to Enhance Stability
复制标题
重新检验原子层沉积 (ALD) 无定形氧化铝 (Al 2 O 3 ) 薄膜的水稳定性以及使用沉积后空气等离子体退火来增强稳定性
DOI：
10.1021/acs.langmuir.1c02574
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发表时间：
2021
期刊：
影响因子：
3.9
通讯作者：
Losego, Mark D.
中科院分区：
文献类型：
--
作者：
Willis, Simon A.;McGuinness, Emily K.;Li, Yi;Losego, Mark D.
无定形氧化铝（氧化铝）薄膜作为用于各种应用的惰性化学屏障是令人感兴趣的。然而，原子层沉积（ALD）的非晶氧化铝薄膜的水稳定性的现有文献仍然不完整，在某些情况下，不一致。由于这些薄膜具有亚稳态的非晶结构，在沉积状态下可能部分水合，因此水合和降解行为可能偏离平衡结晶Al 2 O3相的预期。沉积条件和水溶液的组成（离子含量）似乎影响无定形ALD氧化铝膜的反应性和稳定性，但为什么这些氧化铝膜水合物，溶剂化物，和/或溶解在近中性pH = 7的条件下，结晶Al 2 O3预计是稳定的，仍然没有得到充分的理解。在这项工作中，我们进行了广泛的X-射线光电子能谱调查的表面化学作为一个功能的水浸泡时间，以揭示形成的羟基氧化物（AlOOH），氢氧化物（Al（OH）3），和可能的碳酸盐物种。我们进一步表明，这些ALD氧化铝膜的空气等离子体退火的简短的沉积后曝光可以显着提高膜的稳定性在近中性pH值的水溶液条件。该等离子体处理的简单性和有效性可以提供通常用于促进低温ALD金属氧化物阻挡层的水稳定性的热退火和封盖处理的新替代方案。
Amorphous aluminum oxide (alumina) thin films are of interest as inert chemical barriers for various applications. However, the existing literature on the aqueous stability of atomic layer deposited (ALD) amorphous alumina thin films remains incomplete and, in some cases, inconsistent. Because these films have a metastable amorphous structure─which is likely partially hydrated in the as-deposited state─hydration and degradation behavior likely deviate from what is expected for the equilibrium, crystalline Al2O3phase. Deposition conditions and the aqueous solution composition (ion content) appear to influence the reactivity and stability of amorphous ALD alumina films, but a full understanding of why these alumina films hydrate, solvate, and/or dissolve in near-neutral pH = 7 conditions, for which crystalline Al2O3is expected to be stable, remains unsolved. In this work, we conduct an extensive X-ray photoelectron spectroscopy investigation of the surface chemistry as a function of water immersion time to reveal the formation of oxyhydroxide (AlOOH), hydroxide (Al(OH)3), and possible carbonate species. We further show that brief postdeposition exposures of these ALD alumina films to an air plasma anneal can significantly enhance the film’s stability in near-neutral pH aqueous conditions. The simplicity and effectiveness of this plasma treatment may provide a new alternative to thermal annealing and capping treatments typically used to promote aqueous stability of low-temperature ALD metal oxide barrier layers.