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在半导体器件制造中已经根深蒂固，它们正在成为封装有机发光显示器和照明、柔性和可穿戴电子以及光伏、电池、超级电容器和其他可再生能源转换和存储器件的重要材料。虽然商用ALD已经很好地开发了金属氧化物，但对金属ALD的新方法的需求强烈且不断增长。由于缺乏能够提供足够的挥发性和自限表面反应能力来满足ALD反应要求的有效的气相还原剂和与ALD兼容的金属前驱体，目前可用的选择相对较少。除了了解稳态金属ALD反应外，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元素反应。特别是，衬底选择性ALD正在成为半导体行业实现先进的亚10 nm特征图案化的严峻挑战。该项目通过将第一性原理建模与使用新型金属前体和还原剂的ALD成核和生长的现场分析相结合来解决这些挑战，以开发新的模型和对先进薄膜反应工程设计重要的基本表面反应的见解。研究项目旨在探索新的可用的金属前体和金属还原剂，以扩大对一系列衬底表面的低温热驱动反应机理的基本了解。通过实验/第一性原理模型相结合的方法对气相/表面化学反应机理有了基本的了解，这可能会导致通过热原子层沉积(ALD)来制备新的纳米级元素金属、半金属和类金属薄膜。新的前体和还原剂的组合，结合从建模中获得的见解，将被用来理解依赖于底物的成核。原位反应分析将改进ALD成核模型，并为改进的选择性区域ALD提供途径。有一项探索ALD成核可逆性的计划，包括新兴的热原子层刻蚀(ALE)工艺。采用从CVD到耦合沉积和蚀刻的策略，新的ALE工艺可以极大地改进和扩展选择性ALD能力。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，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.