解决三甲基铝和水原子层沉积半反应的热,Journal of the American Chemical Society

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解决三甲基铝和水原子层沉积半反应的热
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2022-08-09 , DOI: 10.1021/jacs.2c05460
Ashley R Bielinski ₁ , Ethan P Kamphaus ₁ , Lei Cheng ₁ , Alex B F Martinson ₁

Affiliation

原子层沉积 (ALD) 是一种表面合成技术，其特点是气相前体和固体基材之间的自限反应。尽管 ALD 工艺已被证明跨越元素周期表，但有必要对提供 ALD 的表面化学有更深入的了解，以实现更高的精度，包括区域和位置选择性生长。_{我们通过校准和时间分辨的原位热释电量热法提供了对三甲基铝 (TMA) 和 H 2} O ALD 半反应的热力学和动力学的新见解。半反应分别产生 3.46 和 2.76 eV/Al 热量，高于基于结晶 Al ₂ O _{3的计算模型预测的热量}基板，并与标准形成热预测的热紧密对齐。热释电薄膜量热仪提供亚毫秒级的时间分辨率，可独特而清晰地解析前体输送和反应动力学。_{观察到两种半反应都表现出多种动力学速率，平均 TMA 半反应速率比 H 2} O 半反应动力学快至少 2 个数量级。将实验热与已发表的计算文献和其他第一性原理建模进行比较，突出了改进我们的模型和对即使是最普遍的 ALD 反应的机械理解的需要。

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Resolving the Heat of Trimethylaluminum and Water Atomic Layer Deposition Half-Reactions

Atomic layer deposition (ALD) is a surface synthesis technique that is characterized by self-limiting reactions between gas-phase precursors and a solid substrate. Although ALD processes have been demonstrated that span the periodic table, a greater understanding of the surface chemistry that affords ALD is necessary to enable greater precision, including area- and site-selective growth. We offer new insight into the thermodynamics and kinetics of the trimethylaluminum (TMA) and H₂O ALD half-reactions with calibrated and time-resolved in situ pyroelectric calorimetry. The half-reactions produce 3.46 and 2.76 eV/Al heat, respectively, which is greater than the heat predicted by computational models based on crystalline Al₂O₃ substrates and closely aligned with the heat predicted by standard heats of formation. The pyroelectric thin-film calorimeter offers submillisecond temporal resolution that uniquely and clearly resolves precursor delivery and reaction kinetics. Both half-reactions are observed to exhibit multiple kinetic rates, with average TMA half-reaction rates at least 2 orders of magnitude faster than the H₂O half-reaction kinetics. Comparing the experimental heat with published computational literature and additional first-principles modeling highlights the need to refine our models and mechanistic understanding of even the most ubiquitous ALD reactions.

更新日期：2022-08-09

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