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Recently, a method for fabricating air channels using a photodefinable sacrificial material (Unity 2203P) with acid-catalyzed degradation at low temperature was reported [J. P. Jayachandran etal J Microelectromech. Syst. 12, 147 (2003)]. The acid is created via a ‘photoacid’ generator (PAG) either photolytically (when exposed to UV irradiation) or thermolytically (when heated to the decomposition temperature of the PAG). This approach to the fabrication of micro air-channel structures using low-temperature decomposable sacrificial materials has applications to air-gap formation for electrical/optical interconnects, microelectromechanical systems, microfluidics, and microreactors. In this study, the surface characteristics of the silica surface after the decomposition of Unity 2203P was explored. It was found that the surface inside the air-channel after low-temperature Unity 2203P decomposition was hydrophilic and was then converted to hydrophobic after higher-temperature treatment. The modification of the silicon surface using silane-based chemistries and a method for creating alternating hydrophobic/hydrophilic textures within a buried air channel has been demonstrated. Trifluoropropyl dimethylchlorosilane was the most effective surface treatment for creating hydrophobic channels. The hydrophobic/hydrophilic nature of the silicon surfaces is shown by the contact angle measurements and x-ray photoelectron spectroscopy analyses. © 2004 American Vacuum Society.