Fabrication of nanofins of TiO₂ and other metal oxides via the surface sol-gel process and selective dry etching

We herein report the fabrication of nanofins of TiO₂ and other metal oxides via photolithography and the surface sol-gel process. A photolithographically fabricated line template on a silicon wafer was coated with a metal oxide nanolayer by the surface sol-gel process. In this study, TiO₂, ZrO₂, HfO₂, SiO₂/TiO₂ and were employed as coating materials. Then, the topmost portion of the coating layer and the template were successively removed using CHF₃ and oxygen plasma, respectively, leaving the sidewalls of the meal oxide layers remaining on the substrate. These fins were self-supporting, and the composition and the inner layer structure of metal oxide walls were controlled by changing the materials and the coating sequence. In the case of TiO₂, the height/width ratio of the fin was 13.2 at the 30-cycle coating and is surprisingly high when compared to that of the conventional photolithography processes.