Patterning of titanium oxide surfaces using inductively coupled plasma for gas sensing

Titanium oxide thin films were deposited at room temperature by reactive magnetron sputtering in a mixture of oxygen and argon on oxidized silicon substrates. The optimal etching characteristics of TiO2 films by an inductively coupled plasma system were investigated. The maximum etch rate of TiO2 was 104 nm/min at fixed 200 W of ICP power and the highest investigated value of RF chuck power of 150 W. Patterning of TiO2 tip arrays by electron beam lithography and dry etching was conducted. Experimental results showed that the exposure dose optimization was a significant parameter for controlling the tip size and its shape. Pyramidal TiO2 tip arrays were successfully fabricated by dry etching in CF4/Ar plasma through a Au nanoparticle mask. The TiO2 tip arrays can be expected to have an important application in gas microsensors.