Templated Site-Selective Deposition of Titanium Dioxide on Self-Assembled Monolayers

Abstract

TiO2 thin films were grown on several kinds of SAMs (self-assembled monolayers) using TC (titanium tetrachloride), TDD (titanium dichloride diethoxide), or TE (titanium tetraethoxide) as a starting material. We discussed the thin film formation mechanism and improvement of feature edge acuity through controlling the reactivity by changing functional groups of starting material and the surface functional groups of SAMs. The deposition of TiO2 from TC or TDD solution was promoted in the silanol group, and the deposition was suppressed on OTS (octadecyltrichloro-silane) SAM. On the other hand, TE was deposited regardless of the type of surface functional group in the whole area of patterned SAMs. The silanol group, which has high hydrophilicity, accelerated the growth of TiO2, and the OTS SAM, which has hydrophobicity, suppressed the growth of TiO2. It is also clarified that the chlorine atom in the starting material has high reactivity with silanol groups of SAMs.