Indium Tin Oxide (ITO) Transparent MEMS Switches

This paper presents transparent conductive oxide (TCO) switches on glass substrates using indium tin oxide (ITO) for the first time. Mechanical properties of the sputtered ITO film on the glass (density : 7.3 gcm^-3, Young's modulus : ~190 GPa) were measured by X-ray reflectivity (XRR) and nano-indentation analysis. Improvement of transmittance, sheet resistance and wet-etching of 1-mum-thick sputtered ITO was obtained through thermal annealing at 230degC. The fabricated MEMS switches made of ITO with a length of 50 mum and width of 10 mum showed the pull-in voltage of 23 V and pull-out voltage of 20 V, and an excellent ON/OFF current ratio of ~10⁶. In addition, up to 10 muA current could flow through the transparent MEMS switch.