Thin film transistor, method of manufacturing the thin film transistor and organic light emitting display device having thin film transistor

A method of manufacturing a thin film transistor, comprising:

• forming a first gate electrode over a substrate;
• forming a gate insulating layer on the first gate electrode;
• forming an semiconductor active layer on the gate insulating layer;
• forming a passivation layer on the active layer and gate insulating layer;
• and
• forming source and drain electrodes, and a second gate electrode on the passivation layer, wherein the source and drain electrodes are electrically connected to the active layer, and wherein the second gate electrode is disposed between the source and drain electrodes.

An organic light emitting display device, comprising:

• a first substrate;
• a second substrate disposed to face the first substrate;
• an organic light emitting device interposed between the first and second substrates, wherein the organic light emitting device comprises i) first and second electrodes, ii) an organic light emitting layer interposed between the first and second electrodes and iii) a thin film transistor configured to control an operation of the organic light emitting device;
• and
• wherein the thin film transistor comprises
• a substrate;
• a first gate electrode formed over the substrate;
• a gate insulating layer formed over the first gate electrode and substrate;
• an active layer, comprising an oxide semiconductor, formed on the gate insulating layer;
• a passivation layer formed on the active layer;
• source and drain electrodes formed on the passivation layer and electrically connected to the active layer;
• and
• a second gate electrode formed on the passivation layer and located between the source electrode and the drain electrode.