Investigation of the ability of a silica “seed” layer to improve the thermal and aqueous immersion stability of alkylsilane monolayers on silicon oxide surfaces

Previously, a “seed” layer has been demonstrated to improve the thermal and immersion stability of organosilane films deposited on titanium nitride and aluminum substrates through the creation of a highly hydroxylated surface favorable for organosilane surface reaction. In order to determine if a similar silica seed layer can improve the stability of similar monolayers deposited on surfaces that are favorable for organosilane surface modification in their native state, the thermal and aqueous immersion stability of various alkylsilane molecular films on clean silicon oxide surfaces and on silicon oxide surfaces treated with the silica seed layer have been investigated. Contact angle, ellipsometry and atomic force microscopy are employed to monitor samples treated with various alkylsilane monolayers as they are subjected to elevated temperatures and aqueous immersion. Nearly identical trends in contact angle and ellipsometric data demonstrate that the silica seed layer does not improve the thermal and aqueous immersion stability of alkylsilane films on silicon oxide surfaces. Furthermore, this study demonstrates the importance of collecting both contact angle and ellipsometric data during immersion experiments, as reliance on contact angle data alone may lead to faulty conclusions regarding film stability.