Drexler Chad I, Moore Kevin B, Causey Corey P, Mullen Thomas J
Department of Chemistry, University of North Florida , Jacksonville, Florida 32224, United States.
Langmuir. 2014 Jul 1;30(25):7447-55. doi: 10.1021/la501645w. Epub 2014 Jun 17.
Hybrid chemical patterning strategies that combine the sophistication of lithography with the intrinsic precision of molecular self-assembly are of broad interest for applications including nanoelectronics and bioactive surfaces. This approach is exemplified by the molecular-ruler process where the sequential deposition of mercaptoalkanoic acid molecules and coordinated metal ions is integrated with conventional lithographic techniques to fabricate registered, nanometer-scale spacings. Herein, we illustrate the capabilities of atomic force microscopy characterization and lithography to investigate the morphology, quality, and local thickness of Cu-ligated mercaptohexadecanoic acid multilayers on Au{111} substrates. These multilayers are a key component utilized in the molecular-ruler process. The rich and varied topographic features of each layer are investigated via contact-mode atomic force microscopy. Using nanoshaving, an atomic force microscopy lithographic strategy that reveals the underlying Au{111} substrate via tip-induced desorption of a molecular film, the local thicknesses of these multilayers are ascertained; these thicknesses are consistent with the anticipated heights for Cu-ligated mercaptohexadecanoic acid multilayers as well as previous ensemble surface analytical measurements. By regulating the force set point utilized during nanoshaving, the upper layer of a Cu-ligated mercaptohexadecanoic acid bilayer is removed, revealing the carboxyl moiety of the lower mercaptohexadecanoic acid layer. This selective nanoshaving demonstrates a simple and practical means to generate three-dimensional multilayers and to reveal buried chemical functionalities within metal-ligated multilayers.
将光刻技术的精密性与分子自组装的内在精确性相结合的混合化学图案化策略，在包括纳米电子学和生物活性表面等应用领域引起了广泛关注。分子尺工艺就是这种方法的一个例子，在该工艺中，巯基链烷酸分子和配位金属离子的顺序沉积与传统光刻技术相结合，以制造出有规律的纳米级间距。在此，我们展示了原子力显微镜表征和光刻技术在研究金{111}衬底上铜连接的巯基十六烷酸多层膜的形态、质量和局部厚度方面的能力。这些多层膜是分子尺工艺中使用的关键组件。通过接触模式原子力显微镜研究了每一层丰富多样的形貌特征。使用纳米刮削技术，一种通过针尖诱导分子膜脱附来揭示底层金{111}衬底的原子力显微镜光刻策略，确定了这些多层膜的局部厚度；这些厚度与铜连接的巯基十六烷酸多层膜的预期高度以及先前的整体表面分析测量结果一致。通过调节纳米刮削过程中使用的力设定点，去除了铜连接的巯基十六烷酸双层膜的上层，露出了下层巯基十六烷酸层的羧基部分。这种选择性纳米刮削展示了一种简单实用的方法，可用于生成三维多层膜并揭示金属连接多层膜中埋藏的化学官能团。
