posted on 2020-03-24, 14:12authored byNandi Vrancken, Tanmay Ghosh, Utkarsh Anand, Zainul Aabdin, See Wee Chee, Zhaslan Baraissov, Herman Terryn, Stefan De Gendt, Zheng Tao, XiuMei Xu, Frank Holsteyns, Utkur Mirsaidov
Dense arrays of high-aspect-ratio
(HAR) vertical nanostructures
are essential elements of microelectronic components, photovoltaics,
nanoelectromechanical, and energy storage devices. One of the critical
challenges in manufacturing the HAR nanostructures is to prevent their
capillary-induced aggregation during solution-based nanofabrication
processes. Despite the importance of controlling capillary effects,
the detailed mechanisms of how a solution interacts with nanostructures
are not well understood. Using in situ liquid cell
transmission electron microscopy (TEM), we track the dynamics of nanoscale
drying process of HAR silicon (Si) nanopillars in real-time and identify
a new mechanism responsible for pattern collapse and nanostructure
aggregation. During drying, deflection and aggregation of nanopillars
are driven by thin-liquid-film instability, which results in much
stronger capillary interactions between the nanopillars than the commonly
proposed lateral meniscus interaction forces. The importance of thin-film
instability in dewetting has been overlooked in prevalent theories
on elastocapillary aggregation. The new dynamic mechanism revealed
by in situ visualization is essential for the development
of robust nanofabrication processes.