Wetting and dewetting on nanostructured surfaces

The continued miniaturization of electronic devices relies heavily on efficient wet processes that are routinely used in lithography, etching and cleaning. Understanding how the geometry of nanostructured surfaces influences wetting and dewetting behavior is critical for minimizing defects and improving process efficiency. However, direct probing of wetting and dewetting dynamics at the nanoscale, especially on topographically patterned surfaces, remains a significant challenge. Conventional experimental techniques based on liquid drop measurements or microscopic imaging often lack the spatial resolution necessary for in situ characterization. In this work, we present novel experimental approaches developed to resolve these nanoscale interfacial processes. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) is used to probe wetting states on nanopatterned surfaces. Owing to the exponential decay of the evanescent field, ATR-FTIR is highly sensitive to changes in the medium surrounding the nanostructures. This enables in situ monitoring of superhydrophobic breakdown dynamics and comparison across different topographically patterned geometries. Direct visualization using environmental transmission electron microscopy (TEM) reveals nanoscale wetting and dewetting dynamics on high aspect ratio Si nanopillars. These advanced characterization techniques provide critical insights that are instrumental in understanding the interactions between nanostructures and liquids.