Organic light emitting diode display

An organic light emitting diode display, comprising:

• a substrate including a first region and a second region;
• a first gate electrode formed over the first region;
• a second gate electrode formed over the second region;
• a first gate insulator formed on the first gate electrode;
• a second gate insulator formed on the second gate electrode;
• a first semiconductor layer formed on the first gate insulator, the first semiconductor layer comprising a first channel region;
• a second semiconductor layer formed on the second gate insulator, the second semiconductor layer comprising a second channel region;
• an interlayer insulator formed over the substrate and over at least part of the first and second semiconductor layers;
• a first etching stop layer formed over the first channel region and surrounded by the interlayer insulator;
• a second etching stop layer formed over the second channel region and surrounded by the interlayer insulator;
• a first source electrode and a first drain electrode contacting the first semiconductor layer through the interlayer insulator;
• a second source electrode and a second drain electrode contacting the second semiconductor layer through the interlayer insulator;
• a passivation layer formed over at least part of the first source electrode, the first drain electrode, the second source electrode and the second drain electrode;
• and
• a gate line formed over the passivation layer and electrically connected with the first gate electrode through the passivation layer and further through the first gate insulator.