Oxide thin film transistor and method of fabricating the same

Abstract

An oxide thin film transistor (TFT) and its fabrication method are disclosed. In a TFT of a bottom gate structure using amorphous zinc oxide (ZnO)-based semiconductor as an active layer, source and drain electrodes are formed, on which the active layer made of oxide semiconductor is formed to thus prevent degeneration of the oxide semiconductor in etching the source and drain electrodes. The oxide TFT includes: a gate electrode form on a substrate; a gate insulating layer formed on the gate electrode; source and drain electrodes formed on the gate insulating layer and having a multi-layer structure of two or more layers; and an active layer formed on the source and drain electrodes and formed of amorphous zinc oxide-based semiconductor, wherein a metal layer such as indium-tin-oxide, molybdenum, and the like, having good ohmic-contact characteristics with titanium and a titanium alloy having good bonding force with oxygen or the oxide-based semiconductor is formed at an uppermost portion of the source and drain electrodes. In a method for fabricating an oxide TFT, a silicon nitride film is deposited with a sputter equipment without the necessity of Hgas so as to be used as a protection layer of oxide semiconductor to thus prevent degradation of the characteristics of the oxide semiconductor.