Fabrication of high-performance ZnO thin-film transistors with submicrometer channel length

A method was developed to fabricate ZnO thin-film transistors (TFTs) with submicrometer channel length. In this scheme, mature process techniques are used to form a suspending hardmask bridge on the wafer surface, which enables the subsequent construction of a TFT by the sequential deposition of gate oxide, ZnO channel layer, and Al source/drain contacts. Excellent electrical characteristics were demonstrated by the fabricated ZnO TFTs that show high ON/OFF current ratio (> 10⁹), low subthreshold swing (89 mV/decade), and high field-effect mobility (41 cm² V s). Very small variation in the device characteristics is also demonstrated.