Advanced Metal Thin Film Nucleation During Atomic Layer Deposition

由原子层沉积（ALD）形成的薄膜电子材料现在在半导体器件制造中已经根深蒂固，它们正在成为有机发光显示器和照明，柔性和可穿戴电子产品，光伏，电池，超级电容器和其他可再生能源转换和存储设备的重要封装材料。虽然金属氧化物的商业化ALD已经发展得很好，但对金属ALD的新方法的需求也在不断增长。由于缺乏有效的气相还原剂和ALD兼容的金属前驱体，目前可用的选择相对较少，这些金属前驱体具有足够的挥发性和自限制表面反应能力，以满足ALD反应的要求。除了了解稳态金属ALD反应之外，迫切需要更详细地了解金属ALD成核，包括定义生长起始过程中的基本反应。特别是，衬底选择性ALD正在成为半导体行业实现先进的亚10nm特征图形的严峻挑战。该项目将第一性原理建模与ALD成核和生长的原位分析相结合，利用新型金属前驱体和还原剂开发新的模型和对基本表面反应的见解，这对先进的薄膜反应工程设计很重要。该研究项目旨在探索新的金属前驱体和金属还原剂，以扩大对一系列基材表面低温热驱动反应机制的基本理解。通过实验/第一性原理模拟相结合的方法对气相/表面化学反应机理的基本理解，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）。新型前体和还原剂的结合以及从建模中获得的见解将用于理解依赖底物的成核。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。计划探索ALD的成核可逆性，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工艺可以显着改进和扩展选择性ALD能力。所提出的方法是独特的，因为选择了新的研究材料，新的建模方法，以及独特的原位原子尺度表面反应表征工具的组合。

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.