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.