Formation and patterning of self-assembled monolayers derived from long-chain organosilicon amphiphiles and their use as templates in materials microfabrication

Thin films of docosyltrichlorosilane (DTS) were deposited by contact printing on the native oxide surface of a Si(100) single-crystal substrate. The nature of these thin-film layers, as characterized via ellipsometry, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and reflection-absorption infrared spectroscopy, show both similarities to and differences from the extensively studied monolayers derived from octadecyltrichlorosilane (OTS). The structure of these films was found to be close packed and highly oriented for all mass coverages investigated. Taken together, the data indicate that the DTS films grow via the nucleation, expansion, and eventual coalescence of islands on the substrate. The patterning abilities of DTS were also investigated by scanning electron and atomic force microscopy. These studies showed little spreading of the DTS in films patterned by microcontact printing either by edge diffusion or by island formation in the nonprinted regions. These properties, which constitute a significant improvement over previously studied alkyltrichlorosilanes, led to a more accurate transfer of the printed image. The ability of the film to serve as a wet chemical etch resist was studied and found to offer marked improvements over OTS films.