Growth behavior of an adsorbed monolayer from a benzophenone-containing trimethoxysilane derivative on a fused silica surface for nanoimprint molds by chemical vapor surface modification

The formation of a monolayer from a benzophenone-containing trimethoxysilane derivative was studied to understand the growth behavior of an antisticking layer from a trimethoxysilane derivative with an alkyl long tail often used as an antisticking layer in nanoimprint lithography. An adsorbed monolayer was formed from 4-{[(3-trimethoxysilyl)propyl]oxy}benzophenone on a fused silica surface by chemical vapor surface modification (CVSM). The growth behavior of the adsorbed monolayer was monitored by UV-visible spectroscopy, and the results were compared with those obtained by contact angle measurement for water and atomic force microscopy. The monolayer formation was confirmed with absorption spectra showing a characteristic absorption band derived from a benzophenone moiety. Changes in contact angle and absorbance with an increase in CVSM period suggested that the monolayer formation was completed in 2 h. The period of 2 h suitable for CVSM was also supported by atomic force microscopy topographic images. These results suggested that the monolayer growth comprises the following three steps: the surface adsorption, condensation and packing, and excess adsorption steps.