Characterization of highly hydrophobic coatings deposited onto pre-oxidized silicon from water dispersible organosilanes

The formation and quality of highly hydrophobic coatings deposited from water dispersible organosilanes onto pre-oxidized single crystal silicon were studied using atomic force microscopy, ellipsometry, dynamic contact angle measurements and electrochemical impedance spectroscopy (EIS). Highly hydrophobic films of a commercially available water dispersible silane and two different cationic alkoxysilanes were prepared by dip coating. It was found using atomic force microscopy that, in general, the structure of these highly hydrophobic films is a continuous film with some particulates attributed to bulk polymerization of the precursor molecule in water. Film defects were quantified using EIS by the value of charge transfer resistance at the hydrofluoric acid/silicon interface. Potential applications of this type of coatings include reduction/elimination of stiction in micro-electromechanical systems, contact printing in materials microfabrication, inhibition of corrosion and oxidation, prevention of water wetting, lubrication and protein adsorption.

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