Double gate type thin film transistor and organic light emitting diode display including the same

1. A double gate type thin film transistor comprising:

a first gate electrode on a substrate;

a gate insulating layer on the first gate electrode;

a semiconductor layer on the gate insulating layer corresponding to the first gate electrode;

an etch stop layer on the semiconductor layer;

source and drain electrodes contacting both sides of the semiconductor layer, respectively, and spaced apart from each other on the etch stop layer;

a passivation layer on the source and drain electrode; and

a second gate electrode on the passivation layer and having a double-layered structure of a transparent electrode and an opaque electrode,

wherein the first gate electrode is electrically connected to the second gate electrode.

2. The transistor according to claim 1 , further comprising a connection electrode connecting the first gate electrode and the second gate electrode, wherein the second gate electrode is connected to the connection electrode through a contact hole.

3. The transistor according to claim 1 , wherein the second gate electrode is semi-transparent by the transparent electrode made of one of ITO or ZnO, and the opaque electrode made of at least one of MoTi, Cu, Al, Mo or Ti.

4. The transistor according to claim 1 , wherein the semiconductor layer is made of an oxide semiconductor material including at least one of In, Ga or Zn, and the first gate electrode is made of ITO or ZnO.

5. An organic light emitting diode display comprising:

a first gate electrode on a substrate;

a gate insulating layer on the first gate electrode;

a semiconductor layer on the gate insulating layer corresponding to the first gate electrode;

an etch stop layer on the semiconductor layer;

source and drain electrodes contacting both sides of the semiconductor layer, respectively, and spaced apart from each other on the etch stop layer;

a passivation layer on the source and drain electrode;

a second gate electrode on the passivation layer and having a double-layered structure of a transparent electrode and an opaque electrode;

a first electrode on the passivation layer and connected to the drain electrode;

a bank layer on the first electrode and having an opening exposing a portion the first electrode;

a light emitting layer in the opening of the bank layer; and

a second electrode on the light emitting layer, wherein the second electrode is different from the second gate electrode.

6. A method of manufacturing a double gate type thin film transistor, the method comprising:

forming a first gate electrode on a substrate;

forming a gate insulating layer on the first gate electrode;

forming a semiconductor layer on the gate insulating layer corresponding to the first gate electrode;

forming an etch stop layer on the semiconductor layer;

forming source and drain electrodes contacting both sides of the semiconductor layer, respectively, and spaced apart from each other on the etch stop layer;

forming a passivation layer on the source and drain electrode; and

forming a second gate electrode on the passivation layer corresponding to the first gate electrode and having a double-layered structure of a transparent electrode and an opaque electrode,

wherein the first gate electrode is electrically connected to the second gate electrode.

7. The method according to claim 6 , further comprising forming a connection electrode connecting the first gate electrode and the second gate electrode, wherein the second gate electrode is connected to the connection electrode through a contact hole.

8. The method according to claim 6 , wherein the second gate electrode is semi-transparent by the transparent electrode made of one of ITO or ZnO, and the opaque electrode made of at least one of MoTi, Cu, Al, Mo or Ti.

9. The method according to claim 6 , wherein the semiconductor layer is made of an oxide semiconductor material including at least one of In, Ga or Zn, and the first gate electrode is made of ITO or ZnO.