Thin film transistor having dual gate structure and a fabricating method thereof

Abstract

The present invention relates to a thin film transistor and a fabricating method thereof, wherein the source and drain wires are located on a substrate and a double gate structure is provided, whereby the driving capacity of on-current is improved and the degradation of a device is reduced. The TFT includes a substrate, a source electrode, a drain electrode and a lower gate electrode on the substrate, a buffer layer covering an exposed surface of the substrate as well as the source, drain and lower gate electrodes. An active layer is formed on the buffer layer, wherein a source region, a drain region, lightly-doped (LD) regions and a channel region are formed in the active layer. A gate insulating layer is formed on the channel and LD regions. An upper gate electrode is then formed on the gate insulating layer over the channel region. A passivation layer then covers the upper gate electrode. A plurality of contact holes are formed in the buffer and passivation layers, wherein the contact holes expose the source and drain electrodes and the source and drain regions. A first interconnection wire connects the source electrode to the source region. A second interconnection wire connects the drain electrode to the drain region.