Stan Gheorghe, Gates Richard S, Hu Qichi, Kjoller Kevin, Prater Craig, Jit Singh Kanwal, Mays Ebony, King Sean W
Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Anasys Instruments Incorporated, Santa Barbara, CA 93101, USA.
Beilstein J Nanotechnol. 2017 Apr 13;8:863-871. doi: 10.3762/bjnano.8.88. eCollection 2017.
The exploitation of nanoscale size effects to create new nanostructured materials necessitates the development of an understanding of relationships between molecular structure, physical properties and material processing at the nanoscale. Numerous metrologies capable of thermal, mechanical, and electrical characterization at the nanoscale have been demonstrated over the past two decades. However, the ability to perform nanoscale molecular/chemical structure characterization has only been recently demonstrated with the advent of atomic-force-microscopy-based infrared spectroscopy (AFM-IR) and related techniques. Therefore, we have combined measurements of chemical structures with AFM-IR and of mechanical properties with contact resonance AFM (CR-AFM) to investigate the fabrication of 20-500 nm wide fin structures in a nanoporous organosilicate material. We show that by combining these two techniques, one can clearly observe variations of chemical structure and mechanical properties that correlate with the fabrication process and the feature size of the organosilicate fins. Specifically, we have observed an inverse correlation between the concentration of terminal organic groups and the stiffness of nanopatterned organosilicate fins. The selective removal of the organic component during etching results in a stiffness increase and reinsertion via chemical silylation results in a stiffness decrease. Examination of this effect as a function of fin width indicates that the loss of terminal organic groups and stiffness increase occur primarily at the exposed surfaces of the fins over a length scale of 10-20 nm. While the observed structure-property relationships are specific to organosilicates, we believe the combined demonstration of AFM-IR with CR-AFM should pave the way for a similar nanoscale characterization of other materials where the understanding of such relationships is essential.
利用纳米尺度效应来制造新型纳米结构材料，需要深入理解纳米尺度下分子结构、物理性质与材料加工之间的关系。在过去二十年中，已经展示了许多能够对纳米尺度进行热、机械和电学表征的计量技术。然而，随着基于原子力显微镜的红外光谱（AFM-IR）及相关技术的出现，才刚刚证明了进行纳米尺度分子/化学结构表征的能力。因此，我们将AFM-IR对化学结构的测量与接触共振AFM（CR-AFM）对机械性能的测量相结合，以研究在纳米多孔有机硅酸盐材料中制造20 - 500纳米宽的鳍状结构。我们表明，通过结合这两种技术，可以清楚地观察到与有机硅酸盐鳍的制造过程和特征尺寸相关的化学结构和机械性能的变化。具体而言，我们观察到末端有机基团的浓度与纳米图案化有机硅酸盐鳍的刚度之间存在反比关系。蚀刻过程中有机成分的选择性去除导致刚度增加，而通过化学硅烷化重新插入则导致刚度降低。将这种效应作为鳍宽度的函数进行研究表明，末端有机基团的损失和刚度增加主要发生在鳍的暴露表面，长度尺度为10 - 20纳米。虽然观察到的结构-性能关系特定于有机硅酸盐，但我们认为AFM-IR与CR-AFM的联合展示应为其他材料的类似纳米尺度表征铺平道路，在这些材料中，理解此类关系至关重要。
