Micron Scale Patterning of Solution-Derived Ceramic Thin Films Directed by Self-Assembled Monolayers

Abstract

Self assembled monolayers patterned by microcontact printing have been used in conjunction with sol-gel processing to selectively deposit oxide thin films with micron-scale lateral resolution. This simple, three step process allows ambient, lithography-free patterning of oxide thin films for integrated microelectronics, optoelectronics, and sensor applications. A variety of patterned structures, such as capacitors and waveguides, have been fabricated from LiNbO₃, Ta₂O₅, PbTiO₃, and BaTiO₃ on technologically important substrates, including Si, Al, Pt, sapphire, and TiN. The technique involves functionalization of substrate surfaces by microcontact printing of octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs). Sol-gel precursors are then spin-coated on the SAMs-patterned surfaces and heat treated to deposit 20 nm-300 nm amorphous oxide layers. Oxide on derivatized regions is removed with mild polishing, yielding patterned films with features as small as 5 μm. For example, data are reported for 80–200nm Ta₂O₅ films to demonstrate the potential applications and mechanisms involved. The effects of sol-gel precursor chemistry, heat treatment, and other processing variables are reported. These results suggest unique potential for microfabrication of ceramic thin films using molecular self assembly and low temperature processing of solution-derived thin films.