Parylene micropillars coated with thermally grown SiO₂

The modification of surface properties frequently requires the binding of suitable compounds to the original surface. Silanes or thiols can be directly covalently bonded to either Si-based materials or Au, thus ruling out polymers. Here, we show the utilization of a layer of SiO₂ with a thickness of a few nanometers that serves as a cross-linker between polymers and silanes providing covalent bonding to the surface. We deposited a polymer onto a thermally oxidized microstructured Si surface followed by subsequent Si removal. We demonstrated a Si-based nanotechnology fabrication method that can be generally used to modify the surface properties of practically any polymer via SiO₂ cross-linking. This can produce any topology, including microstructures, nanostructures, or composite microstructure/nanostructures terminating in different shapes, since all the steps involving polymer deposition are conducted at room temperature after the Si surface has been thermally oxidized. This technique opens a broad field of new applications for polymers in microstructures and nanostructures that have stable water surface contact angle values with the contact angle set by demand for gecko-mimicking structures or lotus leaf inspired surfaces.