Patron Alexandra M, Coleman Kayleigh L, Mullen Thomas J
Department of Chemistry and Biochemistry, University of North Florida, Jacksonville, FL 32224, USA.
Micromachines (Basel). 2024 Jun 26;15(7):826. doi: 10.3390/mi15070826.
Hybrid strategies that combine conventional top-down lithography with bottom-up molecular assembly are of interest for a range of applications including nanolithography and sensors. Interest in these strategies stems from the ability to create complex architectures over large areas with molecular-scale control and precision. The molecular-ruler process typifies this approach where the sequential layer-by-layer assembly of mercaptoalkanoic acid molecules and metal ions are combined with conventional top-down lithography to create precise, registered nanogaps. However, the quality of the metal-ligated mercaptoalkanoic acid multilayer is a critical characteristic in generating reproducible and robust nanoscale structures via the molecular-ruler process. Therefore, we explore the assembly of alkanethiolate monolayers, mercaptohexadecanoic acid (MHDA) monolayers, and Cu-ligated MHDA multilayers on Au{111} substrates using atomic force microscopy and in situ dynamic spectroscopic ellipsometry. The chemical film thicknesses in situ dynamic spectroscopic ellipsometry agree with previous ex situ surface analytical methods. Moreover, in situ dynamic spectroscopic ellipsometry provides insight into the assembly process without interrupting the assembly process and potentially altering the characteristics of the resulting chemical film. By following the real-time dynamics of each deposition step, the assembly of the Cu-ligated MHDA multilayers can be optimized to minimize deposition time while having minimal impact to the quality of the chemical film.
将传统的自上而下光刻技术与自下而上的分子组装相结合的混合策略，在包括纳米光刻和传感器在内的一系列应用中备受关注。对这些策略的兴趣源于能够在大面积上以分子尺度的控制和精度创建复杂的结构。分子尺过程就是这种方法的典型代表，其中巯基链烷酸分子和金属离子的逐层顺序组装与传统的自上而下光刻技术相结合，以创建精确的、对齐的纳米间隙。然而，金属连接的巯基链烷酸多层膜的质量是通过分子尺过程生成可重复且稳定的纳米级结构的关键特性。因此，我们使用原子力显微镜和原位动态光谱椭偏仪，研究了金{111}衬底上硫醇盐单层、巯基十六烷酸（MHDA）单层和铜连接的MHDA多层膜的组装。原位动态光谱椭偏仪测得的化学膜厚度与先前的非原位表面分析方法一致。此外，原位动态光谱椭偏仪能够在不中断组装过程且不潜在改变所得化学膜特性的情况下，深入了解组装过程。通过跟踪每个沉积步骤的实时动态，可以优化铜连接的MHDA多层膜的组装，以最小化沉积时间，同时对化学膜的质量影响最小。
