Thin film transistor, display device including the same, and method of manufacturing the display device

A display device comprising:

• a first thin film transistor including a first circuit gate electrode, a second circuit gate electrode, a first circuit semiconductor, a second circuit semiconductor, a circuit source electrode, and a circuit drain electrode;
• and
• a second thin film transistor including a first pixel gate electrode, a second pixel gate electrode, a pixel semiconductor, a pixel source electrode, and a pixel drain electrode,
• wherein the first circuit semiconductor includes a polycrystalline semiconductor, and the second circuit semiconductor and the pixel semiconductor includes an amorphous semiconductor.

A method of manufacturing a display device, the method comprising:

• forming a first circuit gate electrode and a first pixel gate electrode;
• forming a second circuit gate electrode and a second pixel gate electrode on the first circuit gate electrode and the first pixel gate electrode, respectively;
• forming a gate insulating layer, an amorphous semiconductor layer, and an ohmic contact layer on the second circuit gate electrode and the second pixel gate electrode;
• forming a circuit source electrode, a circuit drain electrode, a pixel source electrode, and a pixel drain electrode on the ohmic contact layer;
• removing portions of the ohmic contact layer, which are exposed between the circuit source electrode and the circuit drain electrode and between the pixel source electrode and the pixel drain electrode;
• forming a first circuit semiconductor made of a polycrystalline semiconductor and a second circuit semiconductor made of an amorphous semiconductor by crystallizing at least a portion of the amorphous semiconductor layer;
• forming an insulating layer on the circuit source electrode, the circuit drain electrode, the pixel source electrode, and the circuit drain electrode;
• and
• forming a transparent conductive layer connected with at least one of the circuit source electrode, the circuit drain electrode, and the circuit drain electrode.