Advanced Metal Thin Film Nucleation During Atomic Layer Deposition

通过原子层沉积（ALD）形成的薄膜电子材料现在在半导体器件制造中根深蒂固，并且它们正在成为有机发光显示器和照明、柔性和可穿戴电子器件以及光电子器件、电池、超级电容器和其他可再生能源转换和存储器件的封装的重要材料。虽然商业ALD对于金属氧化物发展良好，但对于金属ALD的新方法存在强烈且不断增长的需求。由于缺乏有效的汽相还原剂和与ALD兼容的金属前体（可提供足够的挥发性和自限制表面反应能力来满足ALD反应要求），目前可用的选择相对较少。除了理解稳态金属ALD反应之外，还迫切需要获得对金属ALD成核的更详细的理解，包括定义生长起始期间的基元反应。特别地，衬底选择性ALD正在成为半导体工业实现先进的亚10 nm特征图案化的严峻挑战。 本项目旨在通过将第一性原理模型与使用新型金属前体和还原剂的ALD成核和生长的原位分析相结合，开发对先进薄膜反应工程设计至关重要的基本表面反应的新模型和见解，以解决这些挑战。该研究项目旨在探索新的可用金属前体和金属还原剂，以扩展对低温热反应的基本理解。驱动的反应机制的范围内的基板表面。结合实验/第一性原理模拟方法开发的气相/表面化学反应机制的基本理解可能会导致新的纳米级元素金属，半金属和类金属薄膜的热原子层沉积（ALD）。新的前体和还原剂的组合，结合从建模中获得的见解将被用来了解衬底依赖的成核。原位反应分析将改进ALD成核模型，并为改进选择性区域ALD提供途径。 有一个计划，探索成核可逆性ALD，包括新兴的热原子层蚀刻（ALE）工艺。采用从CVD到耦合沉积和蚀刻的策略，新的ALE工艺可以显著提高选择性ALD的能力。所提出的方法是独特的，因为选择了新的材料来研究，新的建模方法，和独特的组合，在原位原子尺度的表面反应表征工具。

Thin film electronic materials formed by atomic layer deposition (ALD) are now well ingrained in semiconductor device manufacturing, and they are emerging as important materials for encapsulation of organic light-emitting displays and lighting, flexible and wearable electronics, and photovoltaics, batteries, supercapacitors and other renewable energy conversion and storage devices. While commercial ALD is well developed for metal oxides, there is a strong and growing need for new approaches for metal ALD. Relatively few options are currently available due to lack of effective vapor-phase reducing agents and ALD-compatible metal precursors that provide sufficient volatility and self-limiting surface reaction capacity to satisfy ALD reaction requirements. Beyond understanding steady-state metal ALD reactions, there is a critical need to attain a more detailed understanding of metal ALD nucleation, including defining elementary reactions during growth initiation. In particular, substrate selective ALD is becoming an acute challenge for the semiconductor industry to achieve advanced sub-10 nm feature patterning. This project addresses these challenges by combining first-principles modeling with in-situ analysis of ALD nucleation and growth using novel metal precursors and reducing agents to develop new models and insights into elementary surface reactions important for advanced thin film reaction engineering design.The research project aims at exploring newly available metal precursors and metal reducing agents to expand fundamental understanding of low temperature thermally-driven reaction mechanisms on a range of substrate surfaces. The fundamental understanding of vapor/surface chemical reaction mechanisms developed by combined experiment/first-principles modeling approach may lead to new nanoscale elemental metal, semimetal and metalloid thin films by thermal atomic layer deposition (ALD). The combination of novel precursors and reducing agents combined with insights gained from modeling will be used to understand substrate-dependent nucleation. In-situ reaction analysis will improve ALD-nucleation models and provide pathways for improved selective area ALD. There is a plan to explore nucleation reversibility in ALD, including emerging thermal atomic layer etching (ALE) processes. Adapting a strategy from CVD to coupling deposition and etching, new ALE processes could refine significantly expand selective ALD capabilities. The proposed approach is unique because of the choice of novel materials to study, new modeling approaches, and unique combinations of in-situ atomic-scale surface reaction characterization tools.