Development and Fabrication of TiO₂ Tip Arrays 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 reactive ion etching (RIE) and RIE with inductively coupled plasma source (ICP) were investigated. Patterning of TiO₂ tip arrays by electron beam lithography and dry etching were developed. Different spot sizes 200 and 500 nm in diameter and with spacing 500 and 1000 nm were investigated with regards to the minimal size and the pyramidal shape. Experimental results have shown that the exposure dose optimization wa a significant parameter for controlling the tip size and its shape. We successfully fabricated the pyramidal TiO₂ tip arrays over an 1 × 1 mm² area. The TiO₂ tip array can be expected to have an important application in gas microsensors.